UBC Theses and Dissertations

UBC Theses Logo

UBC Theses and Dissertations

Nematodes in British Columbia vineyards : indicators of soil food web responses to compost amendments… Smit, Rosanne 2009

Your browser doesn't seem to have a PDF viewer, please download the PDF to view this item.

Item Metadata

Download

Media
24-ubc_2009_fall_smit_rosanne.pdf [ 228.65kB ]
Metadata
JSON: 24-1.0067730.json
JSON-LD: 24-1.0067730-ld.json
RDF/XML (Pretty): 24-1.0067730-rdf.xml
RDF/JSON: 24-1.0067730-rdf.json
Turtle: 24-1.0067730-turtle.txt
N-Triples: 24-1.0067730-rdf-ntriples.txt
Original Record: 24-1.0067730-source.json
Full Text
24-1.0067730-fulltext.txt
Citation
24-1.0067730.ris

Full Text

Nematodes in BC vineyards: Indicators of soil food web responses to compost amendments and impacts of the plant-parasite, Mesocriconema xenoplax.  by Rosanne Smit B.Sc. (Agro), University of British Columbia, 2002  A thesis submitted in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE in THE FACULTY OF GRADUATE STUDIES (Soil Science)  THE UNIVERSITY OF BRITISH COLUMBIA (Vancouver) September 2009 © Rosanne Smit, 2009  Abstract Vineyard owners in the Okanagan valley of BC are increasingly reporting underperforming blocks of grapevines. Until recently, plant parasitic nematodes were overlooked as factors contributing to decreased vigor in Okanagan vineyards. Analysis of soil from several underperforming vineyards revealed the presence of several species of plant parasitic nematodes, including ring nematodes (Mesocriconema xenoplax), that could be causing economically important damage to grapevines.  M. xenoplax has been associated with grapevines in most major grape-growing regions of the world. Research conducted in field microplots in Oregon and California indicate that M. xenoplax can cause significant reductions in grapevine growth. The impact of plant parasitic nematodes and M. xenoplax in particular on grapevines under British Columbia growing conditions has not yet been determined.  The research objectives were to determine if M. xenoplax has detrimental effects on growth of self-rooted vines and three rootstocks growing in sandy soils typical of the most south Okanagan vineyards and also to determine if application of compost to the root zone of mature grapevines decreases M. xenoplax population densities and enhances nematode community indicators of soil food web enrichment and structure.  After two growing seasons of microplot trials, M. xenoplax decreased trunk diameters and pruning weights of self-rooted vines (Merlot) but did not decrease growth parameters of any of the rootstocks evaluated (Riparia Gloire, 44-53M, 3309C).  Composted layer manure was surface-applied to the root zone of established vines in two commercial vineyards for three consecutive years at modest rates. At the first sample date, six months after the last compost application, all nematode trophic groups were more abundant in the compost-amended plots than in the fertilizer-treated plots indicating fluxes of nutrients through the soil food web. The enhancement of the soil food web did not appear to persist through the second growing season.  Results from this research show that compost applications are beneficial to freeliving nematode communities in sandy soils of the Okanagan, at least in the short term, and  ii  may buffer root feeding damage by plant parasitic nematode populations, especially M. xenoplax, which is indeed detrimental to grapevines.  iii  Table of contents Abstract .............................................................................................................................. ii Table of contents ...............................................................................................................iv List of tables.......................................................................................................................vi List of figures ....................................................................................................................vii Acknowledgements..........................................................................................................viii Co-authorship statement ...................................................................................................ix 1. Introduction .................................................................................................................... 1 1.1. Grape growing in the Okanagan Valley ..................................................................... 1 1.2. Literature review........................................................................................................ 2 1.2.1. Nematodes as components of the soil ecosystem .............................................. 2 1.2.2. Plant parasitic nematodes................................................................................... 2 1.2.2.1. Ring nematodes (Mesocriconema spp.)....................................................... 3 1.2.2.2. Root lesion nematodes (Pratylenchus spp.) ................................................. 4 1.2.2.3. Dagger nematodes (Xiphinema spp.)........................................................... 4 1.2.3. Plant parasitic nematode management............................................................... 4 1.2.4. Using rootstocks as a management practice for growers .................................... 4 1.2.5. Free-living nematodes as indicators of soil health............................................... 5 1.2.6. Structure and diversity indices ............................................................................ 6 1.2.7. Compost application and its effects on soil and nematode populations............... 7 1.3. Objectives.................................................................................................................. 8 1.4. Hypotheses tested..................................................................................................... 8 1.5. Literature cited..........................................................................................................10 2. Nematode population composition under compost treatments in vineyard field trials in the South Okanagan. ...........................................................................................15 2.1. Introduction...............................................................................................................15 2.1.1. Hypotheses........................................................................................................17 2.2 Materials and methods ..............................................................................................18 2.2.1. Research site and experiment set-up.................................................................18 2.2.2. Soil sampling and nematode analysis ................................................................21 2.2.3. Statistical analysis .............................................................................................22 2.3. Results and discussion.............................................................................................22 2.3.1. Nematode community characterization ..............................................................22  iv  2.3.2. Plant parasites...................................................................................................23 2.3.3. Indicators of food web enrichment and nutrient turnover....................................28 2.3.4. Indicators of food web structure and diversity ....................................................33 2.4. Conclusion................................................................................................................36 2.5. Literature cited..........................................................................................................39 3. Field microplots: determining the impacts of Mesocriconema xenoplax on grapevines in the Okanagan Valley. ................................................................................45 3.1. Introduction...............................................................................................................45 3.1.1. Hypotheses........................................................................................................48 3.2. Materials and methods .............................................................................................48 3.2.1. Development of nematode cultures....................................................................48 3.2.2. Preliminary trial - Impacts of M. xenoplax on self-rooted Pinot Grigio.................49 3.2.3. Rootstock trial - Impacts of M. xenoplax on rootstocks and self-rooted Merlot ...50 3.2.4. Soil sampling and nematode analysis ................................................................51 3.2.5. Plant growth parameters....................................................................................51 3.2.6. Statistical analysis .............................................................................................52 3.3. Results and discussion.............................................................................................52 3.3.1. Preliminary trial - Impacts of M. xenoplax on self-rooted Pinot Grigio.................52 3.3.1.1. Nematode establishment ............................................................................53 3.3.1.2. Plant growth parameters .............................................................................55 3.3.2. Rootstock trial - Impacts of M. xenoplax on rootstocks and self-rooted Merlot ...58 3.3.2.1. Nematode establishment ............................................................................58 3.3.2.2. Plant growth parameters .............................................................................58 3.4. Conclusion................................................................................................................61 3.5. Literature cited..........................................................................................................62 4. Conclusions...................................................................................................................65 4.1 Research conclusions ...............................................................................................65 4.2. Strengths and weaknesses of the thesis research....................................................67 4.3. Recommendations for future research......................................................................68 4.4. Overall contribution of the thesis research to the field of study .................................69 4.5. Potential applications of the research findings ..........................................................69 4.6. Future research directions in the field .......................................................................70 4.7. Literature cited..........................................................................................................71 Appendices........................................................................................................................73  v  List of tables Table 2.1. Soil analysis for Bullpine and Tennant sites were averages of four 0-30cm samples analyzed by Waters Agricultural Laboratories Inc., Ga, USA. ........................18 Table 2.2. Compost analyses for PARC-Agassiz composts applied to Bullpine and Tennant vineyard trials for 2005, 2006 and 2007.......................................................................20 Table 2.3. Calculated application rates, total and potentially available nitrogen (kg/ha) applied for three subsequent years at both vineyard sites. ..........................................21 Table 2.4. Nematode genera and c-p rankings used to characterize the nematode community at the Bullpine and Tennant’s vineyard research sites. Identification was carried out at four sample dates; Fall 2007, Spring, Summer and Fall 2008. ...............23 Table 2.5. Summary of P-values for repeated measures analysis of variance for both vineyards together for plant parasite species; M. xenoplax, Pratylenchus spp. and Xiphinema spp.............................................................................................................24 Table 2.6. Summary of P-values for key factors in repeated measures analysis of variance, and means for bacterivorous, fungivorous, omnivorous and predacious nematodes, and Enrichment, Structure and diversity indices. ................................................................29 Table 3.1. Mean abundance of M. xenoplax (per 100 g/soil) in all pots except six controls. Mean and maximum values were calculated from all five sample dates. .....................54 Table 3.2. Two-sample t-Test assuming unequal variances for control pots and pots with M. xenoplax and corresponding prune weights and stem diameters.................................55 Table 3.3. Co-efficients of correlations between selected M. xenoplax counts (by date, maximum, average, average minus last count date) and plant growth parameters (stem diameter and prune weight). ........................................................................................56 Table 3.4. Mean and maximum values of M. xenoplax in rootstock treatments and on selfrooted Merlot. ..............................................................................................................59 Table 3.5. Mean trunk cross sectional area (TCSA) and prune weight of all rootstocks and self-rooted vines with and without nematodes for spring 2009 data. ............................59  vi  List of figures Figure 2.1. Mean M. xenoplax counts for both Tennant’s and Bullpine vineyard sites for four sample dates under compost and fertilizer treatments. ................................................26 Figure 2.2. Mean Pratylenchus spp. counts for both Tennant’s and Bullpine vineyard sites for four sample dates under compost and fertilizer treatments.....................................27 Figure 2.3. Mean values of bacterivorous nematodes under compost and fertilizer treatments for four sample dates. Means that do not have the same letter are significantly different (P>0.05). ....................................................................................30 Figure 2.4. Mean values of fungivorous nematodes under compost and fertilizer treatments for four sample dates. Means that do not have the same letter are significantly different (P>0.05). .....................................................................................................................31 Figure 2.5. Mean values of Enrichment Index under compost and fertilizer treatments for four sample dates. Means that do not have the same letter are significantly different (P>0.05). .....................................................................................................................32 Figure 2.6. Mean values of omnivorous and predacious nematode species under compost and fertilizer treatments for four sample dates. Means that do not have the same letter are significantly different (P>0.05). ..............................................................................33 Figure 2.7. Mean values of Structure Index under compost and fertilizer treatments for four sample dates. Means that do not have the same letter are significantly different (P>0.05). .....................................................................................................................34 Figure 2.8. Mean values of Shannon Index under compost and fertilizer treatments for four sample dates. Means that do not have the same letter are significantly different (P>0.05). .....................................................................................................................35 Figure 2.9. Bullpine and Tennant’s vineyards Enrichment and Structure Index means from four sample dates for compost and fertilizer treatments...............................................36 Figure 3.0. Mean stem diameter 2008 with maximum M. xenoplax count over five sample dates for corresponding microplot. P value <0.05. .......................................................57 Figure 3.1. Prune weight 2008 with average M. xenoplax count over the five sample dates for each corresponding microplot. P value <0.05. ........................................................57 Figure 3.2. Mean 2009 pruning weights for three rootstocks and self-rooted vines inoculated with or without M. xenoplax. Values with different letters are significantly different (P<0.05). .....................................................................................................................60  vii  Acknowledgements I would like to thank the BC Wine Grape Council and Agriculture and Agri-Food Canada for financial support of this project.  Thanks to my committee members Sue Grayston for feedback and Maja Krzic for agreeing to participate on my committee when the end of my program was near.  Much gratitude goes to my academic supervisor, Art Bomke, for his continuous support and guidance through years. Art saw my potential long before I did and after a decade of knowing him, I am still inspired by his commitment to his students.  I would like to thank Tom Forge, my research supervisor, for his guidance and endlessly contagious interest in all things “nematode”. It has been a privilege to learn from and work with such an intelligent person. His knowledge of nematology has been incredibly helpful and allowed me a greater understanding of my research project. Without Tom’s encouragement, I would not have done so well throughout my graduate studies.  My friend, ‘sister’ and other mom, Marg for giving me a safe place to stay while in Agassiz. It made long days in front of the microscope bearable to know there was a friendly face, lively conversation and a yummy meal waiting for me at ‘home’.  Much gratitude goes to my family; to Auntie Linda, Lisa and Maria who kept me sane with ‘Sunday night’ dinners, to Andrew, for his support and providing ‘agriculture’ therapy (aka- milking his cows) when I needed a brain break.  To Mom and Dad, for their emotional (and sometimes financial) support throughout the years. I am blessed to have an incredibly supportive family and a Mom who has always said to me, “You can do it!” Their encouragement and faith in my abilities kept me going.  Lastly, to Stacy for his support and constancy during my months as a ‘road warrior’ driving back and forth from the coast to the Okanagan to do field work, sometimes on a weekly basis. Somehow we worked it out despite our schedules and the miles between us.  viii  Co-authorship statement Chapters 2 and 3 were co-authored by Dr. Tom Forge and Dr. Gerry Neilsen for publication.  Rosanne Smit, thesis author, was responsible for trial set-up, sample and data collection, some of the statistical analysis and data interpretation and cooperation with the co-author during the preparation of the manuscripts.  Dr. Tom Forge, research supervisor, initiated the research program, provided guidance in experimental design, trial set-up, statistical analyses, data interpretation, and preparation of the manuscript.  Dr. Gerry Neilsen initiated and maintained the field experiments on compost utilization which were sampled for this research. He also provided technical support for setup and maintenance of the rootstock microplot experiment.  ix  1. Introduction 1.1. Grape growing in the Okanagan Valley Grape growers in the Okanagan valley of British Columbia (B.C.) have been increasingly reporting weak growth and poor vigor in vineyard blocks. Until recently, plant parasitic nematodes have been overlooked as a potential factor affecting the vigor of wine grapes in this region. Many Okanagan vineyards are located on exceptionally sandy soils that are naturally low in organic matter so areas of poor growth could be mistakenly attributed to low fertility, water stress or other soil or vine pathogens. Until now, there has been little research of soil-related factors affecting vineyard performance in the Okanagan region and grape growers have had to rely primarily on recommendations derived from research conducted in California or other grape growing regions of the United States and abroad.  In recent years, analyses from a selection of under-performing vineyard blocks in the south Okanagan have revealed the presence of several species of plant-parasitic nematodes that could potentially cause economically-important damage to grapes. Large populations of plant parasitic ring nematodes (Mesocriconema spp.) were discovered during a previous three year private research project. This was accompanied with observations of root lesion (Pratylenchus spp.) and dagger (Xiphinema spp.) nematodes, from several vineyard blocks in the south Okanagan exhibiting poor above-ground growth and sparse, necrotic root systems. The northern root-knot nematode (Meloidogyne hapla) has also been detected in Okanagan vineyards, although its distribution appears to be more sporadic than ring, root-lesion and dagger nematodes (T. Forge, pers. comm. 2009). Ring nematodes were largely overlooked in B.C. vineyards until 2005 because nematode extraction methods previously employed were inappropriate for efficient recovery of this group of nematodes.  Most Okanagan vineyards are typically managed using chemical fertilizer, pesticides and herbicides. In most vineyards, herbicides are used to maintain an approximately 1 meter wide weed-free strip of soil in the grape root zone, with a perennial grass cover maintained in the alley between the rows. Consequently, there is little addition of organic matter to the grape root zone. Lately, interest has been growing regarding the use of composts or other soil amendments to improve soil properties in the root zone. Composts are widely reputed to improve soil physical and chemical properties, enhance root growth,  1  and suppress root pathogens. Addition of compost has been associated with either increased or decreased populations of plant-parasitic nematodes (Forge et al., 2003; 2008). The use of compost as a soil amendment in Okanagan vineyards is currently limited.  Better knowledge of the influences of composts on plant-parasitic nematodes and population dynamics of free-living nematodes are needed to clarify best management practices using composts in grape production. 1.2. Literature review 1.2.1. Nematodes as components of the soil ecosystem Nematodes are the most abundant life forms on earth. They are multi-celled, colorless, microscopic roundworms that live in nearly every habitat on earth; in marine and freshwater, in humans and animals as parasites and in the soil environment. Nematodes occupy every trophic level of the soil food web and are indentified by their feeding habits; bacterivores, fungivores, predators and omnivores, and plant feeders (Yeates et al., 1993). Nematodes are either free-living species, those that do the beneficial decomposition and recycling of nutrients in the soil, or plant parasites that live in (endoparasites) or on (ectoparasites) roots and can be vectors for disease and viruses. The plant parasites are easily identified by the large needle-shaped apparatus (stylet) which enables them to pierce and feed on roots. 1.2.2. Plant parasitic nematodes Plant-parasitic nematodes are recognized as important pathogens of grapevines in most major grape-growing regions of the world (Brown et al., 1993; McKenry, 1981; Raski, 1988). As plant-parasitic nematodes feed on roots, they can reduce root growth, compromising water and nutrient uptake. Root damage caused by nematodes can also allow secondary soil-borne pathogens into roots and thereby enhance tissue necrosis and either contribute to decreases in vigor and productivity, and potentially kill the vines. Aboveground, nematode damage is often obscure as the damage to roots does not cause specific above ground symptoms but rather results in weak plants with poor growth and reduced vigor, symptoms that are often assumed to be due to poor nutrition or droughty soils. The extent of damage cause by nematodes is influenced by various factors including soil type, climate, grape variety and rootstock as well as management factors such as deficit irrigation.  2  Although economic loss estimates are subjective due to unknown pathogenicity of location specific plant parasitic nematodes, losses due to yield and production decline could ultimately be very detrimental to the industry. For example, Stirling et al. (1992) estimated 7% yield losses to nematodes in Australian vineyards, while in California vineyards yield losses to root-knot nematodes alone were estimated to cause 20% yield loss (McKenry, 1984). Plant parasitic nematode populations are regulated by antagonistic organisms including nematophagous fungi, bacteria and predacious mites and nematodes (Khan and Kim, 2005). Four groups of plant parasitic nematodes, M. xenoplax, Pratylenchus spp., Meloidogyne spp., and Xiphinema spp. have been observed in the Okanagan valley. 1.2.2.1. Ring nematodes (Mesocriconema spp.) Nematodes in the genus Mesocriconema are collectively known as ring nematodes. These nematodes are generally short squat nematodes, ranging in length from 0.40 mm to 0.78 mm (Bongers, 1988) with limited mobility and conspicuous cuticular annules or ‘rings’ that make it relatively easy to identify nematodes in this group. One particular species, Mesocriconema xenoplax, is widely distributed in vineyards around the world. M. xenoplax was largely overlooked in BC vineyards until 2005 because nematode extraction methods previously employed, which are based on nematode mobility, were inappropriate for efficient recovery of this group of nematodes. M. xenoplax has a broad host range among woody perennials and tends to be more abundant in sandy soils since those soils are dominated with large pores allowing locomotion (Seshadri, 1964).  The first experiments determining the parasitic habits of M. xenoplax were carried out on Thompson seedless grapes under greenhouse conditions where root feeding and population increases on the plants were observed (Raski and Radewald, 1958). Further field-based studies whereby wine grapes were inoculated with M. xenoplax have exhibited damaging effects (McKenry et al., 2001a; Pinkerton et al., 2004; Santo and Bolander, 1977) although in some cases the vines did not show decreases in vigor (Nigh, 1965; Raski and Radewald, 1958).  In California, grape yields were impacted in vineyards where more than 500 M. xenoplax per kilogram of soil were observed (McKenry, 1992). M. xenoplax was found in 85% of 70 vineyards surveyed in Oregon, as well as many replant vineyards (Pinkerton et al., 1999). Pinkerton et al. (2004) reported that M. xenoplax reduced root growth of young  3  self-rooted Chardonnay in field microplots in coastal Oregon by about 75%; pruning weights and grape yield in the fourth growing season were reduced by 58% and 33%, respectively. In subsequent research, Pinkerton et al. (2005) demonstrated that the impact of this nematode on grapes varies with cultivar, and speculated that grapevine age and other environmental stressors also influence the impact of this nematode. Although the impact of this nematode is likely to vary with environmental conditions, there is no information on the potential damage that this nematode species may cause under Okanagan growing conditions, which are substantially different from coastal Oregon and California. . 1.2.2.2. Root lesion nematodes (Pratylenchus spp.) Endoparasitic Pratylenchus species have been found in most underperforming vineyards in the Okanagan Valley (Forge, pers. comm. 2009). The dominant species in BC vineyards appears to be Pratylenchus penetrans but this has not yet been confirmed. Most past research on pathogenesis and management of root-lesion nematodes has been conducted in California, Australia, and the Mediterranean, and has been focused at P. vulnus which probably differs from P. penetrans in terms of pathogenicity to grapevines. 1.2.2.3. Dagger nematodes (Xiphinema spp.) Dagger nematodes are ectoparasites that are endemic to southern B.C. vineyards and potential vectors for grapevine fanleaf virus. Xiphinema spp. have been observed in fruit orchards in the Okanagan (Vrain and Yorston, 1987) as well as vineyards in the same locale (Graham et al., 1988). 1.2.3. Plant parasitic nematode management Currently, pre-plant fumigation is the most effective method for reducing nematode populations and improving vine establishment for the first couple of years after planting. However, fumigation never completely eliminates nematode populations and there is considerable anecdotal evidence that nematode populations in fumigated soil eventually return to levels greater than pre-fumigation (Forge et al., 2001). Soil fumigants are broadspectrum biocides, which also kill beneficial soil organisms that contribute to the natural regulation of pest nematode populations and benefit plant growth. 1.2.4. Using rootstocks as a management practice for growers The use of resistant or tolerant rootstocks is perhaps the most cost-effective and environmentally-appropriate mean of managing plant-parasitic nematodes in a highly  4  infested soil (Winkler et al., 1974). Resistance is the ability of a plant to prevent reproduction of a particular nematode while tolerance is the ability of a plant to grow normally in the presence of a particular nematode. Rootstocks are used for a multitude of reasons, including potential protection from soil-borne pests and pathogens (McKenry and Anwar, 2006). Prior research from California and Oregon has identified rootstocks resistant and/or tolerant to Pratylenchus vulnus (not P. penetrans), M. xenoplax, and other plant parasitic nematode species (McKenry et al., 2001a, 2001b; Pinkerton et al., 2005). However, there can be substantial variation among nematode species and among populations within species in terms of their capacity to reproduce and cause damage to various rootstocks (Pinkerton et al., 2005). Resistance among rootstocks may vary with nematode populations (Cain et al., 1984) or with site conditions (Nicol et al., 1999). 1.2.5. Free-living nematodes as indicators of soil health The composition of a nematode community depends on many factors including vegetation, soil type, climate, soil moisture, and soil organic matter. Nematodes make good bio-indicators of soil health because they occupy key positions in the soil food web, respond rapidly to disturbance and enrichment, do not move very far very quickly, and many species can suspend their life processes and survive extreme environmental events such dehydration or freezing (Bongers and Ferris, 1999).  The nematode community may be used as a bio-indicator of soil quality because community composition correlates with decomposition and nitrogen cycling (Neher, 2001). The composition of a nematode community changes with inputs of resources such as a compost or manure amendment. Bacteria and fungi feeding nematodes are responsive to resource enrichment which indicate fluxes in nutrients in the soil (Ferris and Bongers, 2006, Ferris et al., 2001).  The presence and relative dominance of certain trophic groups are important in assessing change in the structure of a nematode community. In order to assess community structure, nematodes need to be sorted into trophic groups and ranked a colonizerpersister (c-p) value. The resultant Maturity Index (MI) is a general indicator of the nematode communities response to environmental stress, addition of resources, or disturbance (Bongers, 1999, 1990). Ferris et al. (2001) added enrichment and structure trajectories to reflect the importance of specific nematode families to either food web  5  enrichment or structure. This Enrichment Index (EI) measures the increased abundance of enrichment opportunists (bacterivores and fungivores in particular) that result from organic matter inputs, tillage, or other environmental factors.  Presence of higher trophic feeders such as omnivores and carnivores indicate greater functional diversity of the nematode community. The Structure Index (SI) measures the level by which the community is dominated by particular families of these higher trophic taxa. Ferris et al. (2001) suggests that assessment of changes in faunal biodiversity or overall soil biodiversity may be determined using taxonomic diversity derived from high c-p and structural weightings that indicate more structured food webs. 1.2.6. Structure and diversity indices Various structural, weighted, and diversity indices are useful in determining changes in nematode community structure. The maturity Index is a weighted mean of the c-p ranking of a total nematode community and its response to a disturbance or amendment (Bongers, 1990). The coloniser/persister (c-p) values range from 1 to 5 on the basis of where specific nematodes occur on a c-p scale in regards to their ability to colonize or persist (Bongers, 1990, 1999). The colonizers (c-p value of 1) are those nematodes that rapidly increase in population in early succession stages. Otherwise known as r-strategists, these nematodes are short lived and feed in enrichment situations. Persisters are those nematodes that occur in more stable, undisturbed habitats, are longer lived, slower to reproduce and more susceptible to stress and disturbance. These nematodes have higher c-p rankings, are otherwise known as K-strategists and consist of mostly predators and omnivores.  Weighted indices, such as the Enrichment Index (EI) and Structure Index (SI), provide additional information about the dynamics of the nematode community structure and overall soil food web, whether it has had disturbance, amendments or stress (Ferris et al., 2001). The Shannon Index of diversity is used to assess diversity of the populations and is described in more detail below. Both structure and diversity indices can be used to indicate changes in functional diversity of the overall nematode community.  Enrichment Index (EI) The EI, which is an expansion of the maturity Index, measures increased abundance of bacterivore and fungivore nematode species that are enrichment opportunists (Ferris et  6  al., 2001). The EI assesses the resources available to the soil food web and response by primary decomposers to those resources.  Structure Index (SI) The SI is a measure of the number of trophic layers in the soil food web and the potential for regulation by predators. Instead of relying on species level identification, the Structure Index (SI) is based on family level nematode identification. It is used to assess changes in faunal biodiversity (Ferris et al., 2001).  Shannon Index (Shan) The Shannon Index measures biodiversity and species richness (Washington, 1984). This measurement takes into account subspecies richness and proportion of each subspecies within a zone. It is weighted towards species richness. 1.2.7. Compost application and its effects on soil and nematode populations Compost has been used for almost a century in field agricultural systems as an organic slow release fertilizer and as a soil builder and source of nutrients. Composting is a managed aerobic decomposition process by which microorganisms present in the environment break down waste material into stable organic residues. In a proper aerobic composting operation, most weed seeds and pathogens are killed by the heat generation, while mineral nutrients and elements are retained.  Compost has certain properties, which can potentially affect soils such as increase soil organic matter content and overall soil tilth, potentially suppressing plant disease and pathogens and increasing nutrient holding capacity. Increases of organic matter content and available P and exchangeable K have been observed in a soil amended with composts derived from municipal waste and sewage sludge (Pinamonti, 1998). Application of municipal compost in various California vineyards has improved soil structure and water retention (Farrell, 2005). Bulluck et al. (2002) found that compost applications enhanced beneficial soil microorganisms and reduced pathogen populations.  Because many Okanagan vineyards are located on exceptionally sandy soils that are inherently low in organic matter, interest has been growing in the use of composts or other soil amendments to improve soil properties. Soil conditions and soil management practices  7  can potentially have substantial influences on the populations of plant-parasitic nematodes. Composts are reputed to enhance root growth and suppress root-pathogens, but actual data on the influences of composts on the nematode-grape root interaction are lacking.  Compost has been used in agricultural studies on berry and fruit varieties in southern B.C. and found to have positive effects on the nutrient status of the plants (Neilsen et al., 2000; Neilsen et al., 1998). Compost applications have also been found to increase bacterivorous nematode populations as well as have influence on the Enrichment Index (Forge et al., 2003). Nahar et al. (2006) found that abundance of enrichment opportunistic nematodes was greater under various composts than under control treatments. Using compost as a soil amendment has been observed to decrease (Abawi and Widmer, 2000; Oka and Yermiyahu, 2002) as well as increase (Forge et al., 2005) populations of plant parasitic nematodes.  Better knowledge of the influences of composts on plant-parasitic nematodes would help to clarify current understanding of the perceived benefits of composts to grape production especially those grown on sandy soils. 1.3. Objectives Objectives of the research project were to:  Determine the effects of compost amendments on nematode population dynamics.  Determine the pathogenicity of ring nematodes on grape vines  Two microplot trials at Pacific Agriculture Research Center-Summerland and two field trials in commercial vineyards of the south Okanagan were set up to address these objectives and test the following hypotheses: 1.4. Hypotheses tested 1. Compost applications will decrease population densities of plant parasitic nematodes. 2. Compost applications will enhance nematode community indicators of food web enrichment. 3. Compost applications will enhance abundance of nematode community indicators of soil food web structure.  8  4. M. xenoplax will reduce overall vine growth. 5. Selected rootstocks will be more tolerant of M. xenoplax feeding than self-rooted vines.  9  1.5. Literature cited  Abawi, G.S. and T.L. Widmer, 2000. Impact of soil health management practices on soilborne pathogens, nematodes and root diseases of vegetable crops. Appl. Soil Ecol. 15: 37-47.  Bongers T. 1988. De Nematoden van Nederland. Natuurhistorische Bibliotheek van de KNNV, nr. 46. Pirola, Schoorl  Bongers, T. 1990. The maturity Index, an ecological measure of environmental disturbance based on nematode species composition. Oecologia 83: 14-19.  Bongers, T. 1999. The maturity Index, the evolution of nematode life history traits, adaptive radiation and cp-scaling. Plant and Soil 212: 13–22.  Bongers T. and H. Ferris. 1999. Nematode community structure as a bioindicator in environmental monitoring. Trends Ecol. Evol. 14:224–28.  Brown, D.J.F., A. Dalmasso, and D.L. Trudgill. 1993. Nematode pests of soft-fruits and vines. Pp. 427-462 in: Plant Parasitic Nematodes in Temperate Agriculture. Dalmasso, A., and Trudgill, D.L. (eds). CAB International, Wallingford, U.K. Bulluck III, L.R., M. Brosius, G.K. Evanylo and J.B. Ristaino. 2002. Organic and synthetic fertility amendments influence soil microbial, physical and chemical properties on organic and conventional farms . Appl. Soil Ecol. 19: 147-160. Cain D.W., M.V. McKenry, and R.E. Tarailo. 1984. A new pathotype of root-knot nematode on grape rootstocks. Journal of Nematology 16: 207–208.  Farrell, M. 2005. Vineyards make switch to ‘four course’ compost. Biocycle. February. 3336.  Ferris, H. and T. Bongers. 2006. Nematode Indicators of Organic Enrichment. Journal of Nematology 38: 3-12.  10  Ferris, H., T. Bongers, and R.G.M. De Goede. 2001. A framework for soil food web diagnostics: Extension of the nematode faunal analysis concept. Appl. Soil Ecol. 18: 13-29.  Forge. T.A. Personal Communication. 2009.  Forge, T.A., S. Bittman, and C.G. Kowlenko, 2005. Impacts of sustained use of dairy manure slurry and fertilizers on population dynamics of Pratylenchus penetrans under tall fescue. Journal of Nematology. 35:207-213.  Forge, T.A., E.J. Hogue, G. Neilsen, and D. Neilsen. 2003. Effects of organic mulches on soil microfauna in the root zone of apple: implications fro nutrient fluxes and functional diversity of the soil food web. Appl. Soil Ecol. 22:39-54.  Forge, T.A., E.J. Hogue, G. Neilsen, and D. Neilsen. 2008. Organic mulches alter nematode communities, root growth and fluxes of phosphorus in the root zone of apple. Appl. Soil Ecol. 39:15–22.  Forge, T., A. Muehlchen, C. Hackenberg, G. Neilsen, and T. Vrain. 2001. Effects of preplant inoculation of apple (Malus domestica Borkh.) with arbuscular mycorrhizal fungi on population growth of the root-lesion nematode, Pratylenchus penetrans. Plant and Soil 236:185-196.  Graham, M.B., B.A. Ebsary, T.C. Vrain, and J.M. Webster. 1988. Distribution of Xiphinema bricolensis and X. pacificum in vineyards of the Okanagan and Similkameen valleys, British Columbia. Can. J. Plant Path. 10: 259-262.  Khan, Z. and Y.H. Kim. 2005. A review on the role of predatory soil nematodes in the biological conrol of plant parasitic nematodes. . Appl. Soil Ecol. 35: 370-379.  McKenry, M.V. 1981. Nematodes. Pp 233-244 in: Grape Pest Management. Flaherty, D.L., Jensen, F.L., Kasimatis, A.N., Kido, H., and Moller, W.J. (Eds.) Publication No. 4105, Division of Agricultural Sciences, University of California.  11  McKenry, M.V. 1992. Nematodes. Pp. 281-293 in D.L. Flaherty, L.P. Christensen, W.T. Lanini, J.J. Marios, P.A. Philips, and L.T. Wilson, eds. Grape pest management. 2nd ed. Publication No. 3343. Oakland, Ca : Division of Agricultural Science, University of California.  McKenry, M.V. and S.A. Anwar. 2006. Nematode and grape rootstock interactions including an improved understanding of tolerance. Journal of Nematology 38:312-318.  McKenry, M.V. 1984. Grape Root Phenology Relative to Control of Parasitic Nematodes. Am. J. Enol. Vitic. 35:206-211.  McKenry, M.V., J.O. Kretsch, and S.A. Anwar. 2001a. Interactions of selected rootstocks with ectoparasitic nematodes. Am. J. Enol. Vitic. 52:304–309.  McKenry, M.V., J.O. Kretsch, and S.A. Anwar. 2001b. Interactions of selected Vitis cultivars with endoparasitic nematodes. Am. J. Enol. Vitic. 52:310-316.  Nahar, M.S., P.S. Grewal, S.A. Miller, D. Stinner, B.R. Stinner, M.D. Kleinhenz, A. Wszelaki and D. Doohan. 2006. Differential effects of raw and composted manure on nematode community, and its indicative value for soil microbial, physical and chemical properties. Appl. Soil Ecol. 34: 140–151.  Neher, D.A. 2001. Role of nematodes in soil health and their use as indicators, Journal of Nematology. 33: 161–168.  Neilsen, G, H. E.J. Hogue, D. Neilsen and B.J. Zebarth. 1998. Evaluation of organic wastes as soil amendments for cultivation of carrot and chard on irrigated sandy soils. Can. J. Soil Sci. 78: 217-225.  Neilsen, G. H., E.J. Hogue, N. Patni, J. Paul and D. Neilsen. 2000. Research on the use of Organic amendments to increase the horticultural productivity of coarse-textured soils. Technical report 2000-1, PARC Summerland.  12  Nicol. J.M., G.R. Stirling, B.J. Rose, D. May, and R. Van Heeswijck. 1999. Impact of nematodes on grapevine growth and productivity: Current knowledge and future directions, with special reference to Australian viticulture. Aust. J. Grape. Wine Res. 5:109-127.  Nigh, E.L. 1965. Effects of Criconemoides xenoplax, Longidorus elongatus, and Xiphinema americanum on root development and growth of Thompson seedless grape. Phytopathology 55:1070.  Oka, Y. and U. Yermiyahu. 2002. Suppressive effects of composts against the root-knot nematode Meloidogyne javanica on tomato. Nematology 4: 891-898.  Pinamonti, F. 1998. Compost mulch effects on soil fertility, nutritional status and performance of grapevine. Nutr. Cycl. Agroecosyst. 51: 239–248.  Pinkerton, J. N., T.A. Forge, L.L. Ivors, and R.E. Ingham. 1999. Distribution of plant parasitic nematodes in Oregon vineyards. Journal of Nematology 31: 624-634.  Pinkerton, J.N., R.P. Schreiner, K.L. Ivors, and M.C. Vasconcelos. 2004. Effects of Mesocriconema xenoplax on Vitis vinifera and associated mycorrhizal fungi. Journal of Nematology 36: 193-201.  Pinkerton, J.N., M.C. Vasconcelos, T.L. Sampaio, and R.G. Shaffer. 2005. Reaction of Grape Rootstocks to Ring Nematode Mesocriconema xenoplax. Am. J. Enol. Vitic. 56:377385.  Raski, D.J. 1988. Nematode parasites of grape. Pp 55-59 in: Compendium of Grape Diseases. Pearson, R.C. and Goheen, A.C. (Eds). APS Press, The American Phytopathological Society, St. Paul, MN.  Raski, D.J. and R.D. Radewald. 1958. Reproduction and symptomology of certain ectoparasitic nematodes on roots of Thompson seedless grape. Plant Dis. Rep. 42:941943.  13  Santo, G.S. and W.J. Bolander. 1977. Effects of Macroposthonia xenoplax on the growth of concord grape. Journal of Nematology 9:215-217.  Seshadri, A.R. 1964. Investigations on the biology and life cycle of Criconemoides xenoplax Raski. Nematologica 23:540-562.  Stirling, G.R., J.M. Stanton and J.W. Marshall. The Importance of Plant-Parasitic Nematodes to Australian and New Zealand Agriculture. Australasian Plant Pathology 21:104-115. Vrain, T.C. and J.M. Yorston, 1987. Plant parasitic nematodes in orchards of the Okanagan Valley of British Columbia. Plant Disease. 71: 85-87. Washington, H.G. 1984. Diversity, biotic, and similarity indices. Water Res. 18: 653.  Winkler A.J., W.M. Kliewer, L.A. Lider. 1974. General Viticulture (2nd ed.). 710 pp. Univ. of California Press, Berkeley.  Yeates, G. W., T. Bongers, R. G. M. de Goede, D. W. Freckman, and S. S. Georgieva. 1993. Feeding habits in soil nematode families and genera—an outline for soil ecologists. Journal of Nematology. 25: 315–331.  14  2. Nematode population composition under compost treatments in vineyard field trials in the South Okanagan.1 2.1. Introduction Compost has been used in agriculture as a slow-release nutrient source and soil builder for almost a century due to its positive effects on organic matter content, nutrient holding capacity, water infiltration and water-holding capacity, soil tilth and potentially suppressing plant disease (Litterick, 2004). In a recent study in a French vineyard on sandy soil, compost applications increased levels of microbial biomass (Morlat and Chaussod, 2008). Applications of compost have been found to enhance beneficial soil microorganism populations (Bulluck et al., 2002; Perucci, 1990), as well as suppress plant pathogen populations (Bulluck et al., 2002; Hoitink and Fahy, 1986). Compost applications have also been found to increase bacterivorous nematode populations and to influence the Enrichment Index (Forge et al., 2003). Abundance of enrichment opportunistic nematodes was found to be greater under composts than under control treatments (Nahar et al., 2006).  Organic matter content and available P and exchangeable K were increased in a vineyard soil amended with composts derived from municipal waste and sewage sludge (Pinamonti, 1998). Compost has been found to have positive effects on soil biological activity (Forge et al., 2003) and the nutrient status of high-density apple grown on soils typical of vineyards in the Okanagan (Neilsen et al., 1998; Neilsen et al., 2000).  Many vineyards in the south Okanagan are located on very sandy soils that are prone to drought, have very low organic matter levels and are prone to development of root health problems. Many grape growers have reported weak vine growth and reduced productivity although up until now poor growth was attributed to low fertility or water stress. Several groups of potentially damaging plant-parasitic nematodes have been found in weak commercial vineyard blocks in the south Okanagan exhibiting poor above-ground growth and sparse, necrotic root systems. These groups of nematodes include the ‘ring’ nematodes (Mesocriconema spp.), ‘root-lesion’ nematodes (Pratylenchus spp.), and ‘dagger’ nematodes (Xiphinema spp.). Mesocriconema xenoplax is known to cause 1  A version of this chapter will be submitted for publication. Smit, R., Forge, T.A., and Neilsen, G.H. Nematode population composition under compost treatments in vineyard field trials in the South Okanagan.  15  significant damage to grapevine root systems (McKenry et al., 2001; Pinkerton et al., 2004; Santo and Bolander, 1977) but relatively little is known of how its population dynamics are influenced by soil and nutrient management practices, particularly under Okanagan Valley growing conditions. Organic amendments are generally thought to stimulate populations of nematode-trapping fungi and predacious nematodes (Akhtar and Malik 2000; Jaffee, 2004; Jaffee et al. 1994), and many studies have reported suppression of plant-parasitic nematodes in soil amended with compost, manure or other organic amendments (Abawi and Widner, 2000; Bulluck et al., 2002; D’Addabo and Sasanelli, 1998; Kaplan et al, 1992; Oka and Yermiyahu, 2002; Stirling et al., 1995).  Free-living nematodes are potentially useful bio-indicators of soil health. The nematode community in most agricultural soils is composed of bacterivores, fungivores, omnivores, predators, root grazers, and the true plant parasites (such as M. xenoplax). Some taxa are opportunists and can respond to environmental changes very quickly, while others are more susceptible to disturbance and stress and have longer lifecycles. They are easy to sample and extract and their morphology is reflective of their feeding habits so classification into trophic groups is relatively straightforward (Bongers and Bongers, 1998; Freckman, 1988; Neher, 2001). The abundance of higher trophic feeders such as omnivorous and carnivorous nematode species indicates greater functional diversity of the nematode community and the soil food web it represents (Ferris et al., 2001). Ferris et al. (2001) proposed the Structure Index (SI) as a measure of the extent to which any given nematode community is dominated by higher-order trophic groups with stable life-cycles. In theory, nematode communities with high relative abundance of predators, diversity, or other indicators of structure represent food webs that are more stable and have greater capacity to regulate opportunistic plant parasites (Sanchez-Moreno and Ferris, 2007).  The structure of nematode communities changes with inputs of resources such as compost or manure amendments (Ferris and Matute, 2003; Forge et al., 2003; 2008). Increases in the production of bacterial and fungal biomass lead to rapid increases in populations of bacterivorous and fungivorous nematodes that graze on the microbial biomass and thereby mineralize nutrients that would otherwise be sequestered in the microbial biomass (Freckman, 1988; Ingham et al., 1985; Verhoef and Brussaard, 1990). Bacterivorous nematodes play a particularly important role in nutrient mineralization, and  16  their abundance has been correlated with nutrient mineralization or plant nutrient status (Forge and Simard, 2001; Forge et al. 2003; Hassink et al., 1993; Parfitt et al., 2005).  While compost utilization is widely perceived to be beneficial, it is an additional production cost and relatively little is known of the extent of benefits when used at moderate rates, such as when it is applied annually according to crop N requirements. Knowledge of the effects of compost on soil biological properties that are directly relevant to crop health and nutrient mineralization would improve understanding of the overall benefits of using compost in Okanagan vineyards.  The overall objective of this study was to compare the effects of compost and chemical fertilizer, when applied as primary sources of nitrogen, on nematode communities in the root zone of wine grape. Our specific objectives were to compare compost and synthetic fertilizer treatments with respect to:   Population densities of Mesocriconema xenoplax and other plant-parasitic species.    Nematode community indicators of food web enrichment that are also indicative of enhanced nutrient fluxes (abundance of microbivorous nematodes, nematode Enrichment Index).    Nematode community indicators of food web structure that are indicative of more stable soil food webs with greater capacity to regulate populations of opportunistic plant parasites (abundance of omnivores and predators, Structure Index, Shannon Index of diversity).  As our study started after three consecutive years (2005-2007) of compost applications and six months after the last compost application, the resultant data assesses the carryover effects of compost inputs on the nematode community. 2.1.1. Hypotheses 1. Compost applications will decrease population densities of plant parasitic nematodes.  2. Compost applications will enhance nematode community indicators of soil food web enrichment.  17  3. Compost applications will enhance abundance of nematode community indicators of soil food web structure. 2.2 Materials and methods 2.2.1. Research site and experiment set-up The study involved analyzing nematode communities from two experiments previously established in spring 2005 by Gerry Neilsen (AAFC, Summerland). Both experimental sites were commercial vineyards (Tennant and Vincor-Bullpine) located on loamy sand soils (Wittneben, 1986) near Oliver, BC. Both sites were irrigated with overhead sprinklers and managed per industry standards. The plants in the Tennant vineyard are Cabernet Sauvignon, mature but unknown planting date, and in the Bullpine vineyard are Merlot 181/S04, planted in 1999. Four soil samples were taken from each vineyard and analyzed for various chemical and nutrient parameters before the experiment was started (Table 2.1). Table 2.1. Soil analysis for Bullpine and Tennant sites were averages of four 0-30cm samples analyzed by Waters Agricultural Laboratories Inc., Ga, USA.  Bullpine vineyard  a  pH in H20  % OM  7.7  1.7  P (ppm)  K (ppm)  Ca (ppm)  Mg (ppm)  CEC  69  151  676  153  5.1  73  163  704  159  5.6  a  Tennant’s vineyard 7.9 1.9 = major nutrients by Mehlich III extraction  At each site, there were six replicate plots of each of six treatments, arranged in a randomized complete block design. The treatments were: 1) low N early application (40 kg N/ha –budbreak) 2) high N early (80 kg N/ha – budbreak) 3) low N late (40 kg N/ha – bloom) 4) high N late (80 kg N/ha – bloom) 5) low N late application (40 kg N/ha – bloom + post harvest) 6) compost  18  A field plot diagram for Tennant’s vineyard can be found in Appendix 1 and Bullpine Vineyard in Appendix 2. Of the 6 treatments earlier established, only two were sampled in this study. These were: 1) low N early application (40 kg N/ha –budbreak) as the grapegrowing industry standard practice for nutrient application and 2) compost. The fertilizer applied at Bullpine was pelletized urea (46:0:0) at the rate of 0.27 kg, 0.64 kg 0-45-0 (P) and 0.38 kg 0-0-60 (K) per plot. Fertilizer was applied from guard to guard as evenly as possible by hand from the edge of the herbicide strip on each side of the vine row. Only urea was applied at Tennant vineyard, in the same manner as at the Bullpine site and at the same rate of 40 kg N/ha. The plot size at Tennant’s vineyard was 27.14 m2 and at Bullpine vineyard was 31.25 m2.  The compost applied in the trial was produced at the PARC-Agassiz Research Station. Principal feedstocks for this compost are layer manure, greenhouse waste and spoiled hay. The compost was made using a turned windrow method, with piles being turned once per week for approximately three months before being placed into curing piles. Composition analysis was carried out by a commercial laboratory (Northwest Labs, Lethbridge, AB) just before it was applied each year (Table 2.2).  19  Table 2.2. Compost analyses for PARC-Agassiz composts applied to Bullpine and Tennant vineyard trials for 2005, 2006 and 2007. PARC Compost a 2005  PARC Compost a 2006  PARC Compost a 2007  54.8 7.1 57.1  43 6.3 67.70  38 6.2 49.55  2.0 1.7 30 15 2100 0.49 1115  2.3 2.0 26 11 276 0.48 2180  2.4 2.0 25 10 858 0.50 2790  3.6 1.6 3.6 1.2 1.4 0.5 0.3  5.7 1.7 3.8 1.7 2.0 0.7 0.3  Compost – physical  moisture % (as received) pH (as received) EC dS/m (as received) CNS (all values on a dry weight basis)  Total nitrogen % Organic nitrogen % Total carbon % C/N ratio Ammonium -N mg/kg Total sulfur % Nitrate and nitrite - N mg/kg  Minerals - Totals (all values on a dry weight basis)  a  Calcium % Phosphorus % P2O5 % Potassium % K2O % Magnesium % Sodium %  4.1 1.3 3.0 1.6 1.9 0.5 0.5  = values are the mean of 2 separate analyses of the same compost.  Compost was surface-applied to the trial sites at a moderate rate for three consecutive years. The rate of compost application was determined by the analyzed nitrogen content with the assumption that 20% would be mineralized and made available for uptake by the plants. Compost application rates were determined to apply approximately 40 kg N/ha (Table 2.3). Compost was reapplied at the same time the fertilizer was applied, aiming for bud break (late April or early May) for each of the three years. Both vineyards were managed according to industry management guidelines (BCMAFF, 2000; BCMAL, 2006).  20  Table 2.3. Calculated application rates, total and potentially available nitrogen (kg/ha) applied for three subsequent years at both vineyard sites.  Application rate (kg per subplot) Bulk material (Mg dry material/ha) Total N (kg N/ha) Potentially available N (kg N/ha)  2005  2006  2007  6.91  4.77  4.20  10.0  8.7  8.3  200  87  83  40  17  17  2.2.2. Soil sampling and nematode analysis Both sites were sampled four times: October 2007 and May, August and October of 2008. The first sample date, October 2007, was six months after the last compost application. At each sample date, ten cores were taken from each plot; each core was taken approximately 30 cm from the vine trunk to a depth of 15 cm, using a 2.5 cm diameter probe, and the ten cores from each plot which were combined to form a composite sample. The samples were kept refrigerated at 40C until nematode extraction commenced, usually within 7 days.  Nematodes were extracted using the centrifugal flotation method. This is the only method that efficiently extracts slow-moving and inactive nematodes as well as active nematodes (Forge and Kipinski, 2008). Ring nematodes are notoriously slow-moving and consequently centrifugal flotation is the method of choice for studies involving ring nematodes. After extraction, nematodes were identified and counted within two weeks of extraction otherwise killed in a hot water bath and subsequently preserved in 4% formalin.  For community structure analysis, nematodes were removed from preserving liquid, carefully washed over a 500-mesh sieve (26-µm aperture) then transferred to a 40 mm by 40 mm counting dish on an inverted microscope. Total nematodes and plant-parasitic nematodes in each sample were counted at 40X magnification. Then, at 400X, the first 100 nematodes observed on a transect through the counting dish were identified to genus level using general morphology (Bongers, 1988). Numbers of nematodes were not corrected for extraction efficiency.  21  The nematode genera were summarized into trophic groups: bacterivore, fungivore, omnivore/predator or plant parasite (Yeates et al., 1993), and the relative abundance and total abundance of each trophic group was calculated and expressed as the number of nematodes per 100 g of soil.  Several indices of nematode community structure were also calculated for each sample. The Shannon Index of diversity was calculated using genus-level abundance data (Washington, 1984). The nematode Enrichment Index (EI) and Structure Index (SI) were calculated as described in Ferris et al. (2001). Briefly, each taxon is assigned a ranking of 1 to 5 depending on its position along the colonizer-persister continuum as proposed by Bongers (1999). The EI is a weighted measure of the relative predominance of taxa with enrichment opportunist characteristics (c-p rankings of 1); these nematodes are primarily bacterivores. Conversely, the SI is a weighted measure of the relative predominance of higher-order feeding groups with c-p rankings of 4 and 5. 2.2.3. Statistical analysis The effect of compost treatment on various nematode parameters was tested using a repeated measures analysis of variance model (SAS Institute, Cary, NC). Site, block, treatment and sample time were primary factors in the model and the four sample times were treated as the repeated measures in the model. When treatment x sample time interaction effects were significant (P < 0.05), paired t-tests were used to assess the significance of difference between compost and fertilizer plots at each of the sample dates. For analyses of plant-parasitic nematode population data, residual plots were inspected to determine the need for log-transformation. 2.3. Results and discussion 2.3.1. Nematode community characterization Out of the 128 samples analyzed (2 sites x 8 blocks x 2 treatments x 4 sample dates), a total of 40 genera identified (Table 2.4). A few species were only found in one of the two vineyards but generally the populations were similar in diversity at each site.  22  Table 2.4. Nematode genera and c-p rankings used to characterize the nematode community at the Bullpine and Tennant’s vineyard research sites. Identification was carried out at four sample dates; October 2007, May, August and October 2008.  a  Bacterivores  Fungivores  Omnivores  Predators  Plant Parasites  Rhabditidae (1) Panagrolaimus (1) Acrobeles (2) a Acrobeloides (2) a Eucephalobus (2) Wilsonema (2) Plectus (2) Anaplectus (2) Chiloplacus (2) Cephalobus (2) Cervidellus (2) Alaimus (4) Monhysteridae (2) Metateratocephalus (3) a Achromadora (3) Prismatolaimus (3)  Aphelenchus (2) Aphelenchoides (2) Ditylenchus (2) Tylenchus (3) Filenchus (3) Aglenchus (3) Coslenchus (3) a Tylencholaimus (4)  Aporcelaimellus (5) a Cephalinchus (3) Mesodorylaimus (5) Dorylaimoides (5) b Nygolaimus (5) Axonchium (4)  Mononchus (4) Sectonema (5) Paraxonchium (4)  Pratylenchus Mesocriconema Xiphinema Helicotylenchus a Heterodera a Tylenchorhynchus b Paratylenchus  = only observed in Tennant’s vineyard, b = only observed in Bullpine vineyard  2.3.2. Plant parasites Ring (M. xenoplax), root lesion (Pratylenchus spp.), and dagger (Xiphinema spp.) nematodes were all observed at both sites on all sampling dates. Although populations were variable, there were some significant results (Table 2.5).  M. xenoplax populations were consistently higher under compost treatments although only significant at the August 2008 sample date. The observed higher value of M. xenoplax populations under the compost treatment suggests that compost applications increase plant nutrient status and potentially outweighed the suppressive effects of the compost. This makes the roots higher quality food for the plant parasitic nematodes and also fosters greater nematode fecundity. As well, compost applications to sandy soils would potentially reduce soil moisture fluctuations which would facilitate greater nematode activity and therefore population buildup.  23  Table 2.5. Summary of P-values for repeated measures analysis of variance for both vineyards together for plant parasite species; M. xenoplax, Pratylenchus spp. and Xiphinema spp.  Site Block Treatment Time Time x treatment  M. xenoplax  Pratylenchus spp.  Xiphinema spp.  <0.0001 0.3285 0.0694 <0.0001 0.3220  0.0009 0.4244 0.3580 0.0045 0.9682  0.0555 0.3552 0.8008 0.1958 0.9177  October 2007  Compost Fertilizer  1.167 1.125  May 2008  78.17 40.69  August 2008  36.92* 27.50  October 2008  16.83 13.13  October 2007  6.750 2.813  May 2008  11.17 4.375  August 2008  3.667 * 0.500  October 2008  24.58 8.50  October 2007  8.583 4.063  May 2008  15.42 36.94  August 2008  16.58 17.00  October 2008  13.42 8.375  n= 16 compost, n= 16 fertilizer * = Means within a column that are significantly different (P>0.05).  Values for compost and fertilizer treatments are # of nematodes per 100g of soil.  24  M. xenoplax nematode populations were highest in the May 2008 count compared to other counts at both trial sites (Table 2.5, Figure 2.1). This may be related to irrigation management and seasonal fluctuations in temperature and precipitation. Grapes have been shown to have two flushes of root growth, one in the spring just prior to bloom and one in the fall just after harvest (McKenry, 1984). M. xenoplax nematode populations increase corresponding to the increase in amount and quality of good root feeding sites at these particular times.  Soil moisture and irrigation (as well as natural precipitation) is higher in the spring than in the fall and results in a flush of root growth by the plants. Population dynamics of ring nematodes appear to be related to host plant root growth dynamics and M. xenoplax populations have been observed, in vineyards, to increase in months of high precipitation and thus high soil moisture and decrease when soil moisture is low (Pinochet and Cisneros, 1986). Therefore, either natural precipitation or irrigation, seem to be an important determinants M. xenoplax population dynamics depend.  M. xenoplax populations were greater at Tennant’s vineyard (mean value of 145 nematodes per 250 g soil under compost treatment and 90 nematodes per 250 g soil under fertilizer treatment) as compared to the Bullpine site (mean value of 35 nematodes per 250 g soil under compost treatment and 13 nematodes per 250 g soil under fertilizer treatment). A threshold level for M. xenoplax on grape was suggested by McKenry (1992) at 125/250 g dry soil. The suggested threshold resulted in 10-25% yield reduction in established vineyards in California. From these values, we can speculate that Tennant’s vineyard would be sustaining root damage and potentially economic losses from the resident M. xenoplax populations if pathogenic potential of the Okanagan populations is comparable to California threshold values.  25  240  Bullpine compost Bullpine fertilizer Tennant's compost Tennant's fertilizer  Mean M. xenoplax count /100 g soil  220 200 180 160 140 120 100 80 60 40 20 0  October 2007  May 2008  August 2008  October 2008  Figure 2.1. Mean M. xenoplax counts for both Tennant’s and Bullpine vineyard sites for four sample dates under compost and fertilizer treatments.  Pratylenchus spp. populations were observed at both vineyard sites although, similar to M. xenoplax nematode populations, higher populations were found in Tennant’s vineyard than at Bullpine vineyard (Figure 2.2). Nematode counts were consistently higher under compost treatments although only significant at the August 2008 sample date. This may be due to the same factors as described above with the M. xenoplax populations. Greater soil nutritional status due to compost applications would potentially increase the nutrient status of the vines and thus more root growth and correspondingly, more feeding sites which can withstand higher population pressure from plant parasitic nematodes. Pratylenchus spp. populations increased in May and October and this corresponds to flushes of grapevine root growth (McKenry, 1984).  Pratylenchus spp. values were significantly different among sites (Table 2.5) and, like M. xenoplax populations, were observed to have much greater populations at Tennant’s vineyard (mean value of 45 nematodes per 250 g soil under compost treatment and 23 nematodes per 250 g under fertilizer treatment) as compared to the  26  Bullpine site (mean value of 1.08 nematodes per 250 g soil under compost treatment and 0.85 nematodes per 250 g soil under fertilizer treatment). Pratylenchus spp. counts were consistently higher under compost treatments although only significant at the August 2008 sample date.  McKenry (1992) suggested a Pratylenchus spp. damage threshold at 50 nematodes/250 g of soil. This population of root lesion nematodes would result in a 1025% reduction in yield in established vineyards. From these values, we can speculate that Tennant’s vineyard would be sustaining damage from the resident Pratylenchus spp. populations if pathogenic potential of the Okanagan populations is comparable to California threshold values. McKenry’s threshold level is for Pratylenchus species in general and not specific so pathogenicity of Okanagan species could potentially be different from the California species (1992). 90 85  Mean Pratylenchus spp. count /100 g soil  80 75  Bullpine compost Bullpine fertilizer  70 65 60  Tennant's compost Tennant's fertilizer  55 50 45 40 35 30 25 20 15 10 5 0  October 2007  May 2008  August 2008  October 2008  Figure 2.2. Mean Pratylenchus spp. counts for both Tennant’s and Bullpine vineyard sites for four sample dates under compost and fertilizer treatments.  There were no statistically significant results for Dagger populations. Xiphinema spp. were observed in both vineyards with Tennant’s vineyard, similar to the other plant parasitic nematode trends observed, having higher mean values (mean value of 70  27  nematodes per 250 g under compost treatment and 78 nematodes per 250 g soil under fertilizer treatment) as compared to the Bullpine site (mean value of 5 nematodes per 250 g under compost treatment and 8 nematodes per 250 g soil under fertilizer treatment). McKenry (1992) also suggested a Xiphinema spp. damage threshold at 100 nematodes/250 g of soil. This population of Xiphinema spp. would result in a 10-25% reduction in yield in established vineyards. In Tennant’s vineyard Xiphinema spp. values border on threshold level and thus may also be contributing to damage. Grape vines, although supporting populations of plant parasitic nematodes, will not necessarily decline in yield or vigour if their root systems are growing and vigorous. This has been observed in ring nematode research on grapevines (Nigh, 1965; Raski and Radewald, 1958). Compost applications could result in a more robust root system and therefore allow the plants to uptake adequate nutrients and water. As well, a ‘healthier’ soil will have more nema-antagonistic organisms.  The damage thresholds noted above for the various plant parasitic species do not take into account the effect of multiple parasites feeding on the same plant. Having several nematode species feeding on the same plant has been observed to have compounding effects on the level of damage. Studies determining injury to grapevines from a mixture of plant parasite nematodes consistently report greater damage than compared to inoculations of only one nematode species (Pinochet et al., 1976; Anwar and Van Gundy, 1989). 2.3.3. Indicators of food web enrichment and nutrient turnover The treatment x time interaction effect was significant for the abundance of bacterivorous nematodes (Table 2.6).  28  Table 2.6. Summary of P-values for key factors in repeated measures analysis of variance, and means for bacterivorous, fungivorous, omnivorous and predacious nematodes, and Enrichment, Structure and diversity indices.  Site Block Treatment Time Time x treatment  Bacterivores  Fungivores  Omnivores and Predators  0.0013 0.7579 0.7277 0.0309 0.0218  0.0003 0.2545 0.3089 0.0004 0.1274  0.1313 0.3416 0.8087 0.0013 0.0144  October 2007  Compost Fertilizer  Site Block Treatment Time Time x treatment  312 * 118  May 2008  211 151  August 2008  144 156  October 2008  317 435  October 2007  69 * 34  May 2008  95 * 35  August 2008  19 13  October 2008  80 45  October 2007  48 * 21  May 2008  29 27  Enrichment Index  Structure Index  Shannon Index  0.8160 0.0667 0.0362 <0.001 0.0210  <0.0001 0.2729 0.4728 0.0002 0.3715  0.3042 0.5705 0.0207 0.0021 0.3910  October 2007  May 2008  Compost 50 29 Fertilizer 46 24 n=16 compost, n=16 for fertilizer  August 2008  41 * 14  October 2008  68 63  October 2007  60 55  May 2008  61 61  August 2008  77 74  October 2008  70 77  October 2007  9 8  May 2008  10 * 8  August 2008  October 2008  67 78  August 2008  72 95  October 2008  8 7  9 7  * = Means within a column that are significantly different (P>0.05).  Values for compost and fertilizer treatments are # of nematodes per 100g of soil for bacterivore, fungivore and omnivore/predator nematodes.  29  Compost significantly increased the abundance of bacterial feeding nematodes relative to the fertilizer amended plots (Figure 2.3) in the sample date closest to the last compost application but not at subsequent sample dates in 2008. The greater abundance of bacterivores under compost indicates that fluxes of nutrients through the food web were enhanced for at least six months after the last compost application. The lack of differences in 2008 suggests that the three year cumulative applications of compost were not adequate to produce a ‘legacy effect’, i.e., enrichment of the soil food web and associated enhancement of nutrient mineralization in subsequent years. 1200  Average number of nemas per 100g/soil  Compost 1000  Fertilizer  800  600 a  400 a  a a  200  a b  a  a  0 October 2007  May 2008  August 2008  October 2008  Figure 2.3. Mean values of bacterivorous nematodes under compost and fertilizer treatments for four sample dates. Means that do not have the same letter are significantly different (P>0.05).  The mean value under compost was significantly higher at the first sample date which was six months after the application date (Figure 2.3). Bacterivore nematode populations were higher in the first two sample dates; this was most likely an immediate result of the last compost application in the vineyards. Bacterivore populations can reproduce quickly in the presence of enhanced food source, which is resultant of the compost additions.  30  Fungivores tended to be higher under the compost treatment at all sample dates, but neither the treatment nor treatment x time interaction were statistically significant in the repeated measures ANOVA (Table 2.6, Figure 2.4). The weak tendency for fungivores to be more abundant under compost treatments through 2008 is probably a reflection of the tendency for fungal decomposition pathways to follow pulses of bacterial decomposition and to be sustained over longer periods (Ferris and Matute, 2003), and the longer life spans of fungivorous nematodes. 250  Average number of nemas per 100g/soil  Compost Fertilizer  200  150  a  100  a a a  50 b  b a a  0 October 2007  May 2008  August 2008  October 2008  Figure 2.4. Mean values of fungivorous nematodes under compost and fertilizer treatments for four sample dates. Means that do not have the same letter are significantly different (P>0.05).  The EI reflects the increased relative abundance of bactivorous and fungivore nematode species (cp-1 rank) that are enrichment opportunists (Ferris et al., 2001). The EI assesses the resources available to the soil food web and response by primary decomposers to those resources. The EI tended to be higher under the compost treatment at all sample dates although only significant at the August 2008 sampling date (Figure 2.5). This is expected because additions of compost will increase the organic matter and resources needed for enhanced bacterial and fungal growth and thus the  31  opportunistic nematode species that feed on these organisms. The compost application increased bacterivore and fungivore enrichment opportunists so there are more primary decomposers overall in the whole nematode community. This is observed as increased EI values and resultant of greater bacterial and fungal abundance and activity. 100  Compost  90  Fertilizer 80  a  Enrichment Index  70  a 60 a 50  a a  40 a  30  a 20 b 10  0  October 2007  May 2008  August 2008  October 2008  Figure 2.5. Mean values of Enrichment Index under compost and fertilizer treatments for four sample dates. Means that do not have the same letter are significantly different (P>0.05).  Tennant’s vineyard supported significantly greater numbers of both bacterivores and fungivores. The bacterivore population at Tennant’s had a mean value of 306 nematodes per 100 g soil for compost and 321 nematodes per 100 g soil for fertilizer treatment compared to the Bullpine site (mean of 172 nematodes per 100 g soil for compost and 111 nematodes per 100 g soil for fertilizer treatment). Soil analysis (Table 2.1) from both site soils before the trials were set up indicate that Tennant’s vineyard has slightly higher organic matter content and inherent soil fertility then the Bullpine site and this may contribute to higher mean values of bacterivores and fungivores at the Tennant’s site.  32  2.3.4. Indicators of food web structure and diversity The treatment x sample time effect was significant for omnivorous and predacious nematodes (Table 2.6). Similar to the bacterivorous nematodes, omnivores and predators were significantly higher under compost treatments for the first sample date (October 2007) but not for any of the subsequent sample dates in 2008 (Figure 2.6). This may be attributed to the increases in lower trophic level decomposer organisms in the higher resource environment after the last compost application. Decomposer organisms reproduce in a flush to correspond with resource inputs but then decrease once the resource is used up. Omnivore and predacious nematodes would subsequently increase in response to an increased food source. 250  Average number of nematodes per 100g/soil  Compost Fertilizer  200  150  a  100 a a  50  a  a a b  a  0 October 2007  May 2008  August 2008  October 2008  Figure 2.6. Mean values of omnivorous and predacious nematode species under compost and fertilizer treatments for four sample dates. Means that do not have the same letter are significantly different (P>0.05).  Neither treatment nor the treatment x time interaction were significant for the SI (Table 2.6, Figure 2.7)). In contrast, there was a significant main-factor effect for the Shannon Index of diversity (Table 2.6), with diversity being greater under compost than chemical fertilizer application (Figure 2.8).  33  100  Compost  90  Fertilizer 80  a  a a a  70 a  Structure Index  a  a  60 a 50  40  30  20  10  0  October 2007  May 2008  August 2008  October 2008  Figure 2.7. Mean values of Structure Index under compost and fertilizer treatments for four sample dates. Means that do not have the same letter are significantly different (P>0.05).  The SI is conceptually linked with diversity, as soil food webs with greater relative abundance of c-p 4 and 5 ranked nematodes tend to be more speciose (Ferris et al., 2001). The SI gives a higher weighting to omnivorous and predacious nematodes (Ferris et al., 2001), and the increase in S-W diversity under compost, without a corresponding increase in SI (Table 2.6, Figure 2.8), suggests that compost may have fostered a greater diversity of bacterivorous and fungivorous nematodes.  34  14  Compost Fertilizer  12  a  10  Shannon Index  a  a a  b  a  8 a  a  6  4  2  0  October 2007  May 2008  August 2008  October 2008  Figure 2.8. Mean values of Shannon Index under compost and fertilizer treatments for four sample dates. Means that do not have the same letter are significantly different (P>0.05).  More structured and/or diverse food webs are expected to be more stable and more likely to contain organism populations that can regulate populations of opportunistic species such as some opportunistic plant pathogens or parasites (Sanchez-Moreno and Ferris, 2007).  The Structure Index (site, time) was significantly different between the two study sites and was higher at the Bullpine site (71 for compost treatment, 78 for fertilizer treatment) than at Tennant’s vineyard (63 for compost treatment and 54 for fertilizer treatment). As was observed with the bacterivore and fungivore populations, soil analysis (Table 2.1) from both site soils before the trials were set up indicate that Tennant’s vineyard has slightly higher inherent soil fertility and organic matter values than Bullpine and this may contribute to higher mean values of SI at the Tennant’s site.  Ferris et al. (2001) proposed that overall condition of the soil food web could be deduced from the position of nematode communities by plotting EI and SI together. Ferris et al. (2001) proposed that soil food webs developing under perennial crops (such  35  as grapes) would be relatively structured and stable and therefore be graphed in B and C Quadrants. Mean values of EI for both vineyards were plotted against mean values of SI (Figure 2.9) and points fell into Quadrants C and D suggesting that the soil food webs at these sites are relatively structured and stable. The Bullpine site was generally more structured than Tennant’s site and both vineyard compost values were more enriched than the corresponding fertilizer values indicating that compost applications did increase enrichment opportunistic nematode species relative to higher c-p ranked species. 100 B  A  bullpine compost bullpine fertilizer  Enrichment Index  tennants compost tennants fertilizer  50  D  C  0 0  50  100  Structure Index  Figure 2.9. Bullpine and Tennant’s vineyards Enrichment and Structure Index means from four sample dates for compost and fertilizer treatments.  2.4. Conclusion Plant parasitic nematode populations generally increased with compost applications and therefore was in disagreement with our hypothesis that compost applications would decrease plant parasitic nematode populations. Likely this outcome was not due to the non-suppressive effects of the compost applied but rather due to enhanced plant nutrient status. Addition of compost tends to improve soil structure, increase water holding capacity and nutrient status which thereby promotes root growth of the plants. A healthier plant will have more and higher quality roots thereby fostering greater nematode reproduction.  36  Compost applications to very sandy soils would potentially improve soil moisture fluctuations, which would facilitate greater nematode activity and therefore population buildup. Even with higher plant parasitic nematode populations, the internal means of control would be greater so the populations would be better regulated than in a nocompost environment. Therefore, higher plant parasitic nematode populations may not be detrimental to the grapevines and cause noticeable damage or yield loss.  It was hypothesized that nematode population community structure will be affected by type of fertilizer added to the soil and nematode indicators of soil food web enrichment would be increased with compost applications. In this study, bacterivore, fungivore, and EI Index all increased under compost application in the short term. The amendment increased enrichment opportunists so there are more primary decomposers in the nematode community overall and this is observed as an increased EI index value. Compost applications increased the resource load in the soil for decomposer organisms such as bacteria and fungi, which enhanced their corresponding nematode feeding group.  It was also hypothesized that compost applications would enhance abundance of nematode indicators of soil food web structure. Increased abundance of omnivorous and predacious nematodes on the first sample date under the compost treatment may be indicative of populations that subsequently increased to correspond to the flush of lower trophic level decomposer organisms. Decomposer organisms reproduce in a flush to correspond with resource inputs but then decrease once the resource is used up. Omnivore and predacious nematodes would subsequently increase in response to an increased food source.  Although the SI was not significantly affected by compost applications, the Shannon Index was higher under compost applications. This suggests that the compost may have fostered a greater diversity of lower trophic level decomposer nematodes, which outweighed any increases in diversity of higher ranked c-p value nematodes such as omnivores and predacious nematodes.  37  The above findings suggest that, although there were short term positive effects from the soil amendment, the three years of compost applications were not sufficient to have long term effects on enrichment of the soil food web and therefore related enhancement of nutrient mineralization in subsequent years after application in this semi-arid region.  38  2.5. Literature cited Abawi, G. S., and T. L. Widmer. 2000. Impact of soil health management practices on soilborne pathogens, nematodes, and root diseases of vegetable crops. Applied Soil Ecology 15: 37–47.  Akhtar, M. and A. Malik. 2000. Roles of organic soil amendments and soil organisms in the biological control of plant-parasitic nematodes (a review). Biores. Technol. 74: 35– 47.  Anwar S.A., S.D. Van Gundy. 1989. Influence of the interaction of Meloidogyne incognita and Pratylenchus vulnus on root-shoot growth parameters in grape. Afro-Asian Journal of Nematology. 3: 5–11.  Bongers, T. 1988. De Nematoden van Nederland: Een identificatietabel voor de in Nederland aangetroffen zoetwater-en bodembewonende nematoden. Stichting Uoitgeverij van de Koninklijke Nederlandse Natuurhistorische Vereniging. Utrecht, 408 pp.  Bongers, T., 1999. The maturity Index, the evolution of nematode life history traits, adaptive radiation and cp-scaling. Plant and Soil. 212: 13–22. Bongers, T., and M. Bongers. 1998. Functional diversity of nematodes. Appl. Soil Ecol. 10: 239-251. BCMAFF. 2000. Management Guide for Grapes for Commercial Growers, 2000-2001 Edition. British Columbia Ministry of Agriculture, Fisheries, and Food.  BCMAL. 2006. Best Practices Guide for Grapes for British Columbia Growers, British Columbia Ministry of Agriculture and Lands. May 2006. Bulluck III, L.R., M. Brosius, G.K. Evanylo and J.B. Ristaino. 2002. Organic and synthetic fertility amendments influence soil microbial, physical and chemical properties on organic and conventional farms . Appl. Soil Ecol. 19: 147-160.  39  D’Addabo, T., and N. Sasanelli. 1998. The suppression of Meloidogyne incognita on tomato by grape pomace soil amendments. Nematologia Mediterranea 26: 145-149. Ferris, H., T. Bongers, and R.G.M. de Goede. 2001. A framework for soil food web diagnostics: extension of the nematode faunal analysis concept. Applied Soil Ecology 18: 13-29.  Ferris, H. and M.M. Matute. 2003. Structural and functional succession in the nematode fauna of a soil food web. Applied Soil Ecology 23: 93-110.  Freckman, D. W. 1988. Bacterivorous nematodes and organic-matter decomposition. Agr. Ecosyst. Environ. 24: 195-217.  Forge, T.A. and J. Kipinski. 2008. Nematodes. In Carter, M.R.and E.G. Gregorich (eds.) Soil Sampling and Methods of Analysis. CRC Press, Boca Raton, FL, pp. 415-425. Forge, T.A. and S.W. Simard. 2001. Structure of nematode communities in forest soils of southern British Columbia: relationships to nitrogen mineralization and effects of clearcut harvesting and fertilization, Biol. Fertil. Soils 34: 170–178. Forge, T.A., E.J. Hogue, G. Neilsen, and D. Neilsen. 2008. Organic mulches alter nematode communities, root growth and fluxes of phosphorus in the root zone of apple. Appl. Soil Ecol. 39: 15–22. Forge, T.A., E.J. Hogue, G. Neilsen, and D. Neilsen. 2003. Effects of organic mulches on soil microfauna in the root zone of apple: implications fro nutrient fluxes and functional diversity of the soil food web. Applied Soil Ecology 22: 39-54. Freckman D.W. 1988. Bacterivorous nematodes and organic-matter decomposition. Agric Ecosyst Environ 24:195–217.  Ingham R.E., J.A. Trofymore, E.R. Ingham and D.C. Coleman. 1985. Interactions of bacteria, fungi, and their nematode grazers: effects on nutrient cycling and plant growth. Ecol Monogr. 55:119–140.  40  Hassink, J., L.A. Bouwman, K.B. Zwart and L. Brussard. 1993. Relationships between habitable pore space, soil biota and mineralization rates in grassland soils. Soil Biol. Biochem. 25: 47–55.  Hoitink, H.A.J. and P.C. Fahy. 1986. Basis for the control of soilborne plant pathogens with composts. Annu. Rev. Phytopathol. 24: 93–114.  Jaffee, B.A. 2004. Do organic amendments enhance the nematode-trapping fungi Dactylellina haptotyla and Arthrobotrys oligospora. Journal of Nematology 36: 267–275.  Jaffee, B.A., H. Ferris, J.J. Stapleton, M.V.K. Norton and A.E. Muldoon. 1994. Parasitism of nematodes by the fungus Hirsutella rhossiliensis as affected by certain organic amendments, Journal of Nematology 26: 152–161.  Kaplan, M., J. P. Noe, and P. G. Hartel. 1992. The role of microbes associated with chicken litter in the suppression of Meloidogyne arenaria. Journal of Nematology 24: 522–527.  Litterick, A.M., L. Harrier, P. Wallace, C.A. Watson and M. Wood. 2004. The role of uncomposted materials, composts, manures and compost extracts in reducing pest and disease incidence and severity in sustainable temperate agricultural and horticultural crop production—a review. Crit. Rev. Plant Sci. 23: 453–479.  McKenry, M.V. 1984. Grape Root Phenology Relative to Control of Parasitic Nematodes Am. J. Enol. Vitic. 35: 206-211.  McKenry, M.V. 1992. Nematodes. Pp. 281-293 in D.L. Flaherty, L.P. Christensen, W.T. Lanini, J.J. Marios, P.A. Philips, and L.T. Wilson, eds. Grape pest management. 2nd ed. Publication No. 3343. Oakland, Ca : Division of Agricultural Science, University of California.  McKenry, M.V., J.O. Kretsch, and S.A. Anwar. 2001. Interactions of selected rootstocks with ectoparasitic nematodes. Am. J. Enol. Vitic. 52: 304–309.  41  Morlat, R., and R. Chaussod. 2008. Long-term additions of organic amendments in a Loire Valley vineyard. I. Effects on properties of a calcareous sandy soil. Am. J. Enol. Vitic. 59: 353-363.  Nahar, M.S., P.S. Grewal, S.A. Miller, D. Stinner, B.R. Stinner, M.D. Kleinhenz, A. Wszelaki and D. Doohan, 2006. Differential effects of raw and composted manure on nematode community, and its indicative value for soil microbial, physical and chemical properties. Appl. Soil Ecol. 34: 140–151.  Neher, D.A. 2001. Role of nematodes in soil health and their use as indicators. Journal of Nematology 33: 161-168.  Neilsen, G,H. E.J. Hogue, D. Neilsen and B.J. Zebarth. 1998. Evaluation of organic wastes as soil amendments for cultivation of carrot and chard on irrigated sandy soils. Can. J. Soil Sci. 78: 217-225.  Neilsen, G.H., E.J. Hogue, N. Patni, J. Paul and D. Neilsen. 2000. Research on the use of Organic amendments to increase the horticultural productivity of coarse-textured soils. Technical report 2000-1, PARC Summerland.  Nigh, E.L. 1965. Effects of Criconemoides xenoplax, Longidorus elongatus, and Xiphinema americanum on root development and growth of Thompson seedless grape. Phytopathology 55: 1070.  Oka, Y., and U. Yermiyahu. 2002. Suppressive effects of composts against the root-knot nematode Meloidogyne javanica on tomato. Nematology 4: 891-898.  Parfitt, R.L., G.W. Yeates, D.J. Ross, A.D. Mackay and P.J. Budding. 2005. Relationships between soil biota, nitrogen and phosphorus availability, and pasture growth under organic and conventional management. Appl. Soil Ecol. 28: 1–13.  Perucci, P. 1990. Effect of addition of municipal solid waste compost on microbial biomass and enzyme activities in soil. Biol. Fertil. Soils 10:221–226.  42  Pinamonti, F. 1998. Compost mulch effects on soil fertility, nutritional status and performance of grapevine. Nutr. Cycl. Agroecosyst. 51: 239–248.  Pinkerton, J.N., R.P. Schreiner, K.L. Ivors, and M.C. Vasconcelos. 2004. Effects of Mesocriconema xenoplax on Vitis vinifera and associated mycorrhizal fungi. Journal of Nematology 36: 193-201.  Pinochet, J., and T. Cisneros. 1986. Seasonal fluctuations of nematode populations in three Spanish vineyards. Revue de Ne´matologie 9: 391–398.  Pinochet J., D.J. Raski, A.C. Goheen. 1976. Effect of Pratylenchus vulnus and Xiphinema Index singly and combined in vine growth of Vitis vinifera . Journal of Nematology. 8: 330–333.  Raski, D.J. and R.D. Radewald. 1958. Reproduction and symptomology of certain ectoparasitic nematodes on roots of Thompson seedless grape. Plant Dis. Rep. 42: 941-943.  Sanchez-Moreno, S. and H. Ferris. 2007. Suppressive service of the soil food web: effects of environmental management. Agric. Ecosyst. Environ. 119: 75–87.  Santo, G.S. and W.J. Bolander. 1977. Effects of Macroposthonia xenoplax on the growth of concord grape. Journal of Nematology 9: 215-217.  Stirling, G. R., S. R. Dullahide, and A. Nikulin. 1995. Management of lesion nematode (Pratylenchus jordanensis) on replanted apple trees. Australian Journal of Experimental Agriculture 35: 247–258.  Verhoef H.A. and L. Brussaard. 1990. Decomposition and nitrogen mineralization in natural and agro ecosystems: the contribution of soil animals. Biogeochem 11:175–211.  Washington, H.G. 1984. Diversity, biotic, and similarity indices. Water Res. 18: 653.  43  Wittneben, U. 1986. Soils of the Okanagan and Similkameen Valleys, Report no. 52, British Columbia Soil Survey, British Columbia Ministry of Environment.  Yeates, G. W., T. Bongers, R. G. M. de Goede, D. W. Freckman, and S. S. Georgieva. 1993. Feeding habits in soil nematode families and genera—an outline for soil ecologists. Journal of Nematology. 25: 315–331.  44  3. Field microplots: determining the impacts of Mesocriconema xenoplax on grapevines in the Okanagan Valley. 1 3.1. Introduction The ring nematode, Mesocriconema xenoplax, was found to be widely distributed among Okanagan orchards in the late 1980s (Vrain and Yorston 1987). However, because M. xenoplax is not an important pathogen of apple, its presence was not considered significant in the context of that study. M. xenoplax was also overlooked in surveys of Okanagan vineyards before 2005 (Graham et al., 1988), probably because nematode extraction methods previously employed were inefficient for recovery of ring nematodes with poor above-ground growth, reduced fruit yields and sparse, necrotic, stubby roots.  Controlled-inoculation studies have demonstrated that M. xenoplax can damage grapevine (McKenry et al., 2001a; Pinkerton et al., 2004; Santo and Bolander, 1977). In California, grape yields were reduced in vineyards where more than 500 M. xenoplax. per kilogram (or recalculated as 50 per 100g) of soil were observed (McKenry, 1992). M. xenoplax was found in 85% of 70 vineyards surveyed in Oregon, as well as many replant vineyards (Pinkerton et al., 1999). Pinkerton et al. (2004) used field microplots to assess the impacts of M. xenoplax on the first four years’ growth of self-rooted Chardonnay and Pinot Noir under field conditions. They found that M. xenoplax reduced fine root biomass and prune weights by about 75 percent and 58 percent, respectively, relative to non-infested. Subsequent studies by Pinkerton et al. (2005) demonstrated that rootstock varieties differ in terms of their capacity to support M. xenoplax population growth and in their tolerance to the nematode. They also suggested that the impact of this nematode on grapes varies with age and other environmental stressors. For example, a rootstock trial by McKenry et al. resulted in all cultivars susceptible to M. xenoplax but then half of those appeared tolerant after 21 months (2001a).  Root-lesion nematodes (Pratylenchus spp.) have been found in the majority of problematic vineyards sampled to date in the Okanagan Valley. Pratylenchus 1  A version of this chapter will be submitted for publication. Smit, R. and Forge, T.A. Determining the impacts of Mesocriconema xenoplax on grapevines in the Okanagan Valley.  45  penetrans, which is an economically important pathogen of a wide variety of horticultural crops in temperate regions (Castillo and Vovlas, 2007) has long been associated with apple in the Okanagan Valley (Vrain and Yorston, 1987). It is assumed that P. penetrans is the main species associated with grape in the Okanagan Valley, but proper identification of the species associated with grape in BC remains to be performed. Most prior research on pathogenesis and management of root-lesion nematodes has been conducted in California, Australia, and the Mediterranean, and has been directed at P. vulnus (Anwar and Van Gundy, 1989; McKenry et al., 2001b; Pinochet et al., 1992; Yamashita and Viglierchio, 1986) which probably differs from P. penetrans in terms of pathogenicity to grapevines.  The use of tolerant or resistant rootstocks is potentially the most cost-effective and environmentally-appropriate means of dealing with plant-parasitic nematodes (Winkler et al., 1974). Most grape scion varieties originate from native European grapevines, Vitis vinifera which are native to the Mediterranean and Asia Minor. Most rootstocks are derived from V. riparia and V. rupestris, both of which are native to North America. Native V. riparia is the most widespread species and occurs naturally in riparian zones throughout the eastern US and north into Quebec. Hybrids of it are globally popular as rootstock material due to its high resistance to the aphid-like root parasite phylloxera (Dactylosphaira vitifoliae). V. rupestris occurs near stream beds in the Midwest and Southern states. It is easy grafted and rooted and crosses of it are also popular due to its resistance to phylloxera. Rootstock use in vineyards was employed after phylloxera was introduced into European vineyards in the mid 1800s and the ensuing epidemic devastated V. vinifera vines. Because phylloxera is native to North America, Vitis varieties such as V. riparia and V. rupestris had co-evolved with the pest and thus had varying degrees of resistance.  While resistance to phylloxera triggered the development and use of rootstocks, subsequent research has revealed important variation among rootstock selections in terms of their suitability for different soil types and fertility, salinity and irrigation regimes, as well as resistance or tolerance to plant-parasitic nematodes. Research from California and Oregon has identified rootstocks resistant and/or tolerant to Pratylenchus vulnus (not P. penetrans), M. xenoplax and other plant parasitic nematode species (McKenry et al., 2001a, 2001b; Pinkerton et al., 2005). There can be substantial  46  variation, however, among nematode species within a genus, and variation among populations within species, in terms of capacity to reproduce and cause damage to grape rootstocks (Pinkerton et al., 2005). In this study, we compared responses to M. xenoplax of self-rooted Merlot to Merlot grafted onto the following three commerciallyavailable rootstocks, all of which were developed in France and are known to advance maturity of the scion. Riparia Gloire V. riparia Bred by Viala and otherwise known as Gloire de Montpellier, this rootstock was first used after the phylloxera epidemic in Europe. It roots and grafts well, has strong phylloxera resistance, but its resistance to plant parasitic nematodes is variable or nil (Christensen, 2003). Riparia Gloire has a short vegetative cycle and is well suited to cold climates. It is known to have low to moderate vigour and has well-branching root system. This rootstock is the third most widely used rootstock in Oregon (Shaffer et al., 2004) and has low tolerance to drought. Riparia Gloire rootstock was found to be intolerant and susceptible to M. xenoplax (Pinkerton et al., 2005). 3309C V. riparia x V. rupestris Otherwise known as 3309 Couderc, this rootstock is not suited to dry soils and imparts moderate vigour (Christensen, 2003). 3309C has a deep well-branching root system and is the most widely used rootstock in Oregon (Shaffer et al., 2004). This rootstock prefers deep well-drained soils and is very susceptible to plant parasitic nematodes. 3309C rootstock was found to be intolerant and susceptible to M. xenoplax (McKenry et al., 2001a; Pinkerton et al., 2005). A nutritional problem associated with 3309C is potassium deficiency (Christensen, 2003). 44-53M V. riparia x (V. cordifolia x V. rupestris) Otherwise known as Malegue 44-53, this rootstock was once widely used in France but has not been widely used in North America partially due to poor magnesium uptake abilities (Shaffer et al., 2004). Its attributes are relatively unknown. 44-53M has good drought resistance (Carbonneau, 1985; Christensen, 2003), imparts moderate vigour and prefers fertile loamy soils.  47  The objectives of this study were to: 1. Assess the pathogenicity of an Okanagan population of M. xenoplax, an Okanagan population of P. penetrans, and a combined inoculation on self-rooted Pinot Grigio and Merlot.  2. Compare self-rooted Merlot and Merlot grafted onto three different rootstocks in terms of their ability to support population growth of M. xenoplax and their sensitivity to M. xenoplax. 3.1.1. Hypotheses 1. M. xenoplax will reduce overall vine growth.  2. Selected rootstocks will be more tolerant of M. xenoplax feeding than self-rooted vines. 3.2. Materials and methods 3.2.1. Development of nematode cultures Experimental populations of Pratylenchus spp. and M. xenoplax from Okanagan vineyards were established in greenhouse pot cultures at PARC-Agassiz to be used as inoculum for the microplot experiments. Pratylenchus spp. One known vineyard site, Cedar Creek vineyard, was observed to be infested only with root-lesion nematodes; no M. xenoplax or root-knot nematodes were observed after several extractions. Drawing on the endoparasitic habit of root-lesion nematodes, a baiting approach was used to obtain a pure culture from the infested vineyard soil. In December 2005, aliquots of this soil were planted with corn, which is known to be a good host for Pratylenchus spp. After one month, roots of the corn plants were washed (presumably leaving only endoparasitic nematodes in the roots), chopped, mixed into fresh potting mix (1:1 Sunshine mix: pasteurized river sand) in two 20 L pots, and the pots were planted with rooted cuttings of Pinot Grigio. A subsample of the chopped roots was placed in a mist chamber for extraction of endoparasitic nematodes to confirm that the corn roots had been colonized by Pratylenchus spp. In early March 2006, soil from the two initial pots of Pinot Grigio was combined, separated into 12 aliquots of  48  approximately 3 L. Each aliquot was then mixed into fresh potting mix and planted in a 20 L pot with a rooted cutting of Pinot Grigio. Before planting out, root samples were taken from 6 pots and nematodes extracted in the mist chamber for 72 hours. The resultant mean population was 45 Pratylenchus spp. nematodes per 4 grams of roots.  M. xenoplax M. xenoplax were hand-picked from samples extracted from soil from a heavily infested Okanagan vineyard in January 2006. Two 20 L pots of potting medium planted with Pinot Grigio were inoculated with 250 hand-picked M. xenoplax and a third pot was inoculated with 500 M. xenoplax nematodes. These plants were grown for two months after which the soil from the pots was combined, mixed and diluted into 12 aliquots of approximately 3 L. Each aliquot was then mixed with fresh potting mix and planted in a 20 L pot with a rooted cutting of Pinot Grigio and left to multiply. Before planting out, soil samples were taken from 6 pots and extracted via sucrose centrifugation with the resultant mean value of 55 M. xenoplax per 100g sample of soil. 3.2.2. Preliminary trial - Impacts of M. xenoplax on self-rooted Pinot Grigio The microplot experiment was established in May 2006, with thirty 25-gallon Rubbermaid® trash bins placed inside thirty concrete microplots located at PARCSummerland. Three 5 cm diameter holes were drilled into the bottom of each trash bin and covered with screen to allow for free drainage. Soil used in the microplots was a native Skaha gravelly sandy loam (Wittneben, 1986) from a field adjacent to the experimental site. The fumigant Basamid® (dazomet) was mixed into the soil at 16 g/microplot (~200 g/m3 soil) as it was backfilled into each microplot. Each microplot was hand-watered to near saturation and then covered with trash bin lids. After one week, the lids were removed and the microplots were allowed to off-gas for two weeks before planting.  Thirty potted plants of self-rooted Pinot Grigio from the greenhouse in Agassiz, B.C. were transplanted into the thirty microplots. Ten of the plants had been growing in M. xenoplax-infested soil, ten in Pratylenchus spp.-infested soil, and ten in non-infested soil. The ten plants of each nematode treatment were arranged in a randomized complete-block experimental design. As each pot was transplanted into its microplot, a  49  single ~150 mL sample of soil and roots was removed and assayed for nematodes. A plot diagram can be found in Appendix 3.  Bark mulch was added around the rubbish bins (in the space between bin and concrete culvert) for insulation and aesthetics. Drip irrigation was set up with one emitter per pot. The grape vines were managed in accordance with conventional industry guidelines for irrigation, fertilization, and weed control. Vines were pruned in April of 2007 and 2008 in the head training method (Strik, 2006). 3.2.3. Rootstock trial - Impacts of M. xenoplax on rootstocks and self-rooted Merlot In early April 2007, 5 trenches were dug at the Summerland research station site in a field with a native Skaha gravelly sandy loam (Wittneben, 1986). The large scale microplot experiment was set up in May 2007, with 180-100 L plastic nursery pots sunk into the trenches with 1 m between pots and 3 m between rows. A 1 m square piece of landscape fabric was placed in the bottom of the pots to cover the drainage holes. Soil was then carefully backfilled around pots.  Fumigation was carried out on April 17-19 , 2007 by backfilling with the excavated soil into the pots and the fumigant Basamid® (dazomet) mixed into the soil at a rate of 16 g per pot (~200 g/m3). The pots were hand-watered to near saturation, and then sealed with plastic. After four weeks, the plastic was removed and pots allowed to off-gas for two weeks.  Self-rooted Merlot, Merlot on Riparia Gloire, Merlot on 3309C, and Merlot on 4453M rootstock were obtained from Bevo Nurseries (Langley, BC) in May 2007, and hardened-off in a cold frame at the Agassiz Research Center. On July 4, 2007 the plants were transported to Summerland and forty microplots were planted with each plant type. At the time of planting, ten microplots of each plant type were inoculated with (1) M. xenoplax, (2) Pratylenchus spp., (3) both nematodes, and (4) nothing. The sixteen combinations of plant type and nematode inoculation were arranged in a randomized complete block design, with ten blocks. A plot diagram can be found in Appendix 4.  50  Nematode inoculation involved adding 290 ml of Pratylenchus and/or 1000 ml of M. xenoplax nematode-infested potting medium from greenhouse cultures described above; non-inoculated controls received comparable amounts of non-infested potting medium. Rates of nematode infestation were: Pratylenchus spp. at 162 per pot (or 1.8 nematodes per litre of soil in the pot), and M. xenoplax at 220 per pot (2.4 nematodes per litre of soil in the pot) and a combination of both infestation rates. The nematode cultures had been previously grown on plants (M. xenoplax on grape, Pratylenchus spp. on corn) in the greenhouse at the Pacific Agri-Food Research Center in Agassiz, B.C.  Drip irrigation was set up with 12 mm poly tape running the length of the row with 2 emitters per pot. Plants were irrigated and fertilized as per industry standards (BCMAL, 2006; BCMAFF, 2006). 3.2.4. Soil sampling and nematode analysis Preliminary trial: Two soil cores were removed from each microplot in November 2006, March and October 2007, and March and October 2008. Cores were taken from midway between the plant stem and edge of the pot, to 20 cm depth using an Oakfield probe with 2.5 cm diameter. Controls were sampled first and then nematode inoculated microplots. Upon collection, the samples were stored in a cooler with icepacks for transport to the lab. Plant parasitic nematodes were extracted from 50 g of soil using sucrose centrifugation extraction method (Forge and Kipinski, 2008) and refrigerated thereafter. Plant parasitic nematodes were counted within a week of extraction.  Rootstock trial: Three soil cores were removed from each microplot in October 2008 and June 2009 as described for the preliminary trial. 3.2.5. Plant growth parameters Preliminary trial: Vine stem diameters were measured the day of transplanting. Vine stems were then measured in two directions, between the 7th and 8th node up from soil level using calipers, once the vines had gone into dormancy. The average of the two values was calculated and recorded. Starting in spring 2007, the vines were pruned down to a  51  single stem and 12 buds. Pruned plant material was then dried in a 60oC oven for 48 hours and dry pruning weights determined.  Rootstock trial: Vine stem diameters were measured fall/winter 2008 and 2009 after seasonal vine growth had stopped. Vine stems were measured in 2 directions, 12 cm up from soil level in each pot. The average of the two values was calculated and recorded. In spring 2008 and 2009, the vines were pruned down to a single stem. Pruned plant material was dried in a 60oC oven for 48 hours and prune weights determined. 3.2.6. Statistical analysis Preliminary trial: M. xenoplax contamination resulted in a range of population densities in the microplots. To quantify the relationship of M. xenoplax population densities to plant growth parameters of stem diameter and prune weights, two sample t-tests were carried out assuming equal variance for growth parameters in control and M. xenoplax infested pots.  Nematode populations (5 sample dates), stem diameter (3 dates) and prune weight (2 dates) data averages were used to calculate a correlation matrix (n = 29). Because the M. xenoplax population densities declined between the spring and fall 2008 sampling, we also used the average M. xenoplax population density through Spring 2008 but not including Fall 2008 counts in the correlation analysis.  Rootstock trial: Data on M. xenoplax populations, prune weight and trunk cross sectional area (TCSA) were analyzed using an analysis of variance (ANOVA) model of SAS (SAS Institute, Cary, NC). Any pots with dead grapevines were excluded from the statistical analysis. 3.3. Results and discussion 3.3.1. Preliminary trial - Impacts of M. xenoplax on self-rooted Pinot Grigio The drainage holes in culvert #30 (a pot with the Pratylenchus spp. treatment) were plugged and the whole area was waterlogged for a week. As a result, although the  52  pot was removed from the culvert and left to drain, the plant died. Therefore only 29 pots were included in the trial. 3.3.1.1. Nematode establishment Pratylenchus spp. population The population of Pratylenchus spp. did not establish in the pots. Very low population densities were observed in a few samples taken early in the experiment. The number of nematode-positive microplots declined from two in November 2006, to one in March 2007 and then none in November 2007. These observations suggest that grape is potentially a poor host for the population of root lesion nematodes we used in this study or the inoculum levels were too low to result in populations taking hold on the root system.  While propagation of this population of Pratylenchus spp. on grape in the greenhouse was successful to use as inoculum, we were unable to develop large population densities under field conditions. Although Pratylenchus spp. is widespread in Okanagan vineyards, establishing a population to take hold in a microplot experiment has proven to be difficult. We speculate that grape is a poor host for this population of Pratylenchus; under greenhouse conditions (stable temperatures, high nitrogen) the grape roots are likely more palatable or able to support nematode reproduction than under field conditions characterized by more variable soil water and temperature regimes (including overwinter freezing) and possibly less succulent roots. Alternatively, the nematodes were inoculated into pots with young plants (low root biomass) so possibly there were not enough roots in the vicinity of the nematodes for them to establish. M. xenoplax population M. xenoplax populations established well although contamination in the small scale trial resulted in a wide range of populations at the end of the three years of research. M. xenoplax were found to have contaminated many of the pots in the small scale microplots. Each of M. xenoplax and control pots were soil sampled at time of grapevine planting and the Pratylenchus-inoculated microplots were root sampled. This procedure did not indicate that the pots were contaminated. Contamination was first observed in the initial inoculum with contamination deduced to have occurred when the  53  Pinot Grigio plants were being grown for the trials. The nematode inoculum was grown directly with the plants so potentially the error occurred in the greenhouse immediately at the start of the trial before setting up the field experiment.  Counts are as follows for M. xenoplax appearance in pots at each observation date. M. xenoplax were found in 5 of the control pots in November 2006 and in 6 control pots in May 2007. M. xenoplax were found in 4 of the control pots in remaining counts; in November 2007, May and November 2008. M. xenoplax were found in 8 out of 10 root lesion pots in November 2006 and then in all root lesion pots in May 2007 and in subsequent counting dates.  Three microplots were completely free of any plant parasitic nematodes on all sampling dates. Two other microplots appeared to have very low numbers of M. xenoplax on one of the five sample dates. One microplot had very low numbers in the second and third counts. Considering the possibility of cross-contamination during extraction, which could lead to erratic appearance of very low numbers of nematodes in samples from non-inoculated microplots, these three microplots were considered as nematode-free controls for the analyses of relationships between M. xenoplax and plant growth parameters.  The mean abundance of M. xenoplax in all M. xenoplax-inoculated and M. xenoplax-contaminated pots is shown in Table 3.1. The three true controls, two controls that had low nematode numbers in first or second count and then none thereafter and one control that had low nematode numbers in second and third counts and none thereafter are not included in the table and as they had low to no ring nematodes for at least three out of the five counting dates. Table 3.1. Mean abundance of M. xenoplax (per 100 g/soil) in all pots except six controls. Mean and maximum values were calculated from all five sample dates. Sampling date November 2006 May 2007 November 2007 May 2008 November 2008  M. xenoplax count mean abundance (per 100 g soil)  Range of M. xenoplax counts (per 100 g soil)  185 324 550 475 215  0 – 689 0 – 1542 0 – 2312 18 – 2325 0 – 615  54  The population of M. xenoplax steadily increased over time for the first two years of the study and then decreased at the last counting date. Under very high nematode pressure, the plants may have had sufficient root damage that they were unable to withstand and maintain the high populations of M. xenoplax. Without the root resource on which to feed and reproduce, the M. xenoplax populations would have decreased. 3.3.1.2. Plant growth parameters Because the Pratylenchus inoculations were unsuccessful, analyses of effects on plant growth were limited to effects of M. xenoplax. T-tests comparing the six M. xenoplax-free microplots with the 26 M. xenoplax-infested microplots indicate that prune weight mean values in 2008 and stem diameter mean values in 2007 and 2008 were significantly higher in control pots as compared to nematode-inoculated pots (Table 3.2). Table 3.2. Two-sample t-Test assuming unequal variances for control pots and pots with M. xenoplax and corresponding prune weights and stem diameters. Prune Stem Stem Stem a b Weight Diameter Diameter Prune Weight Diameter May-07 Apr-08 Oct-06 Oct-07 Oct-08 Pots without M. xenoplax (n=6) 82.38 11.85 13.98 42.52 5.55 Pots with M. xenoplax (n=23) P-value a b  39.44  50.15  5.95  10.20  11.32  0.0675  0.0045  0.1023  0.0428  0.0013  = grams of dried plant material = value was calculated from two measurements taken at the same height on each plant  Several microplots consistently had relatively low M. xenoplax population densities so correlation analyses were used to assess the relationships between several expressions of M. xenoplax population densities and plant growth parameters (Table 3.3).  55  Table 3.3. Co-efficients of correlations between selected M. xenoplax counts (by date, maximum, average, average minus last count date) and plant growth parameters (stem diameter and prune weight). Prune Weight  Prune Weight  May-07 Apr-08 M. xenoplax counts 2007 March -0.1916* -0.0007 2007 November -0.0948 2008 May -0.1009 2008 November -0.2265 Max count -0.2711 -0.0094 Average count Average count (minus -0.2531 nov 2008 count) *Highlighted values are significant at P<0.05.  Prune Weight  Stem Diameter  Stem Diameter  Stem Diameter  average  Oct-06  Oct-07  Oct-08  -0.1373 -0.0461 -0.0660 -0.1313 -0.1586  -0.0104 -  <-0.0001 -0.1886 -0.0207 -  -0.0576 -0.3071 -0.2832  -0.1453  -  -0.1716  -0.2928  Both 2008 prune weight and stem diameter data were more closely correlated with the M. xenoplax populations than other dates (Table 3.3). Statistically significant negative correlations were observed between nematode counts and plant growth parameters (Table 3.3) with the strongest correlations between 2008 stem diameter and the maximum (Figure 3.1), average and average minus last nematode counts, respectively.  There was also a significant correlation between 2008 prune weight and  max, average (Figure 3.1) and average minus the last nematode count. These observations suggest that the M. xenoplax population pressure had detrimental effect on the root system and therefore decreased vine vigour and growth, especially in the final year of the study.  56  2008 stem diameter mean value of 2 measurements per vine in mm)  18 16 14 12 10 8  y = -0.0017x + 12.964 R2 = 0.3071  6 4 2 0 0  500  1000  1500  2000  2500  Maximum M. xenoplax count over 5 sample dates  Figure 3.0. Mean stem diameter 2008 with maximum M. xenoplax count over five sample dates for corresponding microplot. P value <0.05.  120  2008 Prune weight (grams of dried plant material)  100  80  y = -0.0558x + 72.483 R2 = 0.2711 60  40  20  0 0  100  200  300  400  500  600  700  800  900  Average M. xenoplax count over 5 sample dates  Figure 3.1. Prune weight 2008 with average M. xenoplax count over the five sample dates for each corresponding microplot. P value <0.05.  57  These observations indicate that nematodes are having detrimental effects on grapevine growth. Pinkerton et al. (2004) had the same result, observing suppression of shoot and root growth on establishing grapevines under M. xenoplax pressure. Their microplot study had the environmental conditions, soil type and management typical of Willamette valley vineyards and the pathogenicity of Oregon M. xenoplax populations could potentially be different from the Okanagan strain. Pinkerton et al. (2004) suggested, from observing M. xenoplax population dynamics and prune data that the carrying capacity of one year old Chardonnay and Pinot Noir was 5 to 8 M. xenoplax per gram of soil.  After one year of growth in the microplot study, the grapevines had a mean nematode count of 3 M. xenoplax per gram of soil. Low nematode numbers in the first year of growth may not have had detrimental effects on the grapevines. After eighteen months of growth, the grapevines had a mean nematode count of 6 nematodes per gram of soil which is in the range of carrying capacity that Pinkerton et al. (2004) proposed. Although the populations may be different in regards to pathogenicity, both microplot trials have shown that M. xenoplax has negative effects on grapevine growth. 3.3.2. Rootstock trial - Impacts of M. xenoplax on rootstocks and self-rooted Merlot 3.3.2.1. Nematode establishment M. xenoplax populations in the large scale trial were variable and this may be indicative of low populations in some of the pots currently. As the populations are still establishing, the M. xenoplax numbers may increase in the upcoming season. Alternatively, the sampling protocol may have “missed” the nematodes as only a small fraction of soil was sampled out of each pot. 3.3.2.2. Plant growth parameters Some of the vines in the trial perished in the winters of 2008 and 2009. The pots were replanted with the same corresponding rootstock or self-rooted vines in spring of 2008. Table 3.4 shows the mean number of M. xenoplax per pot, for the spring 2009 count as well as positive count for each treatment at the time of sampling. The pots had  58  very wide ranging populations and some individual pots had extremely high M. xenoplax counts. Self-rooted plants had the lowest values for both mean and maximum nematode numbers. Table 3.4. Mean and maximum values of M. xenoplax in rootstock treatments and on selfrooted Merlot. Rootstock x M. xenoplax  Mean May 2009 M. xenoplax count a (per 100 g soil)  Maximum May 2009 M. xenoplax count (per 100 g soil)  Pots positive for M. xenoplax within b treatment  Notes  2 overwinter vine mortalities 4 overwinter vine 3309C 116 1181 11/20 mortalities 5 overwinter vine 44-53M 43 369 13/20 mortalities 1 overwinter vine Riparia Gloire 160 2534 9/20 mortality a = Average M. xenoplax number was calculated from all pots of given rootstock treatment including pots with 0 M. xenoplax count or with dead plants b = Pots with M. xenoplax observed in spring 2009 count with live or dead plants.  self-rooted  10  74  8/20  Only the self-rooted vines showed significant results with the inoculated plants having very low prune weights compared to the nematode inoculated vines (Table 3.5). Trunk cross sections on the self-rooted control vines had larger values than the inoculated vines but were not significant. There were no significant results for any of the rootstocks. Table 3.5. Mean trunk cross sectional area (TCSA) and prune weight of all rootstocks and self-rooted vines with and without nematodes for spring 2009 data. Rootstock Nematode treatment Spring 2009 TCSA* Winter 2009 Prune 2 a (cm ) Weight* (g dried plant material) 41.02 a without M. xenoplax Self-rooted vines 72.30 a 12.35 b with M. xenoplax Self-rooted vines 61.42 a 3309C 3309C  without M. xenoplax with M. xenoplax  152.56 a 159.75 a  53.86 a 63.71 a  44-53M 44-53M  without M. xenoplax with M. xenoplax  182.15 a 168.10 a  43.69 a 47.81 a  Riparia Gloire Riparia Gloire  without M. xenoplax with M. xenoplax  139.85 a 141.99 a  51.48 a 51.56 a  a  = trunk cross sectional area. *= dead vines were removed from statistical analysis for Prune weight and TCSA Means within a column that do not have the same letter are significantly different (P>0.05).  M. xenoplax had significant detrimental impact on prune weight on self rooted vines but there were no significant difference among rootstocks (Figure 3.2). There  59  were no significant results for trunk cross sectional area for any of the vines, but tended to have slightly higher values for nematode infested vines. 3309C and Riparia Gloire rootstocks were previously shown to be very susceptible to M. xenoplax damage (Pinkerton et al., 2005) although they did not appear to be susceptible to M. xenoplax on the basis of earlier data. 90  ring nematode  80  Prune weights (g of dried material)  no nematode 70  A  60  A A  50  A  A  A B  40  30  20 A 10  0  44-53M  Riparia Gloire  3309C  self-rooted  Figure 3.2. Mean 2009 pruning weights for three rootstocks and self-rooted vines inoculated with or without M. xenoplax. Values with different letters are significantly different (P<0.05).  M. xenoplax may have significant impacts on these rootstocks in future years, after populations have increased to damaging levels. It is interesting to note that even though growth of self-rooted vines was significantly reduced by M. xenoplax, population densities of the nematode were lower in spring 2008 in pots with self-rooted vines than in pots with rootstocks. This underscores the sensitivity of self-rooted vines to M. xenoplax. Alternatively, it is possible that the pathogenicity of Okanagan M. xenoplax populations is different from Oregon populations. Pinkerton et al. (2005) found that Pacific Northwest M. xenoplax populations had different reproduction rates compared to California M. xenoplax populations growth on the same rootstocks. As the M. xenoplax  60  populations were so variable in the spring 2009 count, a few pots with extremely high counts tended to skew the means and resulted in higher mean values.  3.4. Conclusion In both the preliminary study and rootstock trial, it was found that M. xenoplax populations indeed had detrimental effects on grapevine stem diameter and prune weight although only on the self-rooted vines in the rootstock trial. In the preliminary trial, pots with higher populations of M. xenoplax showed correspondingly lower prune weights (in 2008) and trunk cross sectional areas (in 2007 and 2008).  M. xenoplax populations multiplied very quickly in the second year of the preliminary trial. From this observation, M. xenoplax populations were expected to increase in the rootstock trial even though they have only been observed at low levels up until now. Although only showing significant detrimental effects on self-rooted vines, with higher populations and greater pressure on the grapevines, M. xenoplax will potentially damage the rootstocks in subsequent growing seasons.  61  3.5. Literature cited Anwar S.A. and S.D. Van Gundy. 1989. Influence of 4 Nematodes on Root and shoot growth parameters in grape. Journal of Nematology. 21: 276: 283.  BCMAFF. 2000. Management Guide for Grapes for Commercial Growers, 2000-2001 Edition. British Columbia Ministry of Agriculture, Fisheries, and Food.  BCMAL. 2006 Best Practices Guide for Grapes for British Columbia Growers, British Columbia Ministry of Agriculture and Lands.  Carbonneau, A. 1985. The early selection of grapevine rootstocks for resistance to drought condition. Am. J. Enol. Vitic. 36: 195-198.  Castillo P, and Vovlas, N. 2007. Pratylenchus, Nematoda, Pratylenchidae: Diagnosis, biology, pathogenicity and management. Nematol. Monogr. Perspectives. 6: 1-530.  Christensen, L.P. 2003. Rootstock Selection. Pp 12-15 in: Wine Grape Varieties in California. University of California Agricultural and Natural Resources Publication 3419, Oakland, CA. http://groups.ucanr.org/iv/files/27344.pdf accessed May 25, 2009.  Forge, T.A and J. Kipinski. 2008. Nematodes. In: Carter, M.R.and E.G. Gregorich (eds.), Soil Sampling and Methods of Analysis. CRC Press, Boca Raton, FL, pp. 415-425.  Graham, M.B., B.A. Ebsary, T.C. Vrain and J.M. Webster. 1988. Distribution of Xiphinema bricolensis and X. pacificum in vineyards of the Okanagan and Similkameen valleys, British Columbia. Can. J. Plant Path. 10: 259-262.  McKenry, M.V. 1992. Nematodes. Pp. 281-293 in D.L. Flaherty, L.P. Christensen, W.T. Lanini, J.J. Marios, P.A. Philips, and L.T. Wilson, eds. Grape pest management. 2nd ed. Publication No. 3343. Oakland, Ca : Division of Agricultural Science, University of California.  62  McKenry M.V., J.O. Kretsch and S.A. Anwar. 2001a. Interactions of selected rootstocks with ectoparasitic nematodes. American Journal of Enology and Viticulture 52: 304–309.  McKenry M.V., J.O. Kretsch and S.A. Anwar. 2001b. Interactions of selected Vitis cultivars with endoparasitic nematodes. American Journal of Enology and Viticulture 52: 310-316.  Pinkerton, J. N., T.A. Forge, L.L. Ivors, and R.E. Ingham. 1999. Distribution of plant parasitic nematodes in Oregon vineyards. Journal of Nematology 31: 624-634.  Pinkerton, J.N., R.P. Schreiner, K.L. Ivors, and M.C. Vasconcelos. 2004. Effects of Mesocriconema xenoplax on Vitis vinifera and associated mycorrhizal fungi. Journal of Nematology. 36: 193-201.  Pinkerton, J.N., M.C. Vasconcelos, T.L. Sampaio and R.G. Shaffer. 2005. Reaction of Grape Rootstocks to Ring Nematode Mesocriconema xenoplax. Am. J. Enol. Vitic. 56: 377-385.  Pinochet, J., S. Verdejo, A. Soler and J. Canals. 1992. Host Range of a Population of Pratylenchus vulnus in Commercial Fruit, Nut, Citrus, and Grape Rootstocks in Spain. Journal of Nematology 24: 693–698.  Santo, G.S., and W.J. Bolander. 1977. Effects of Macroposthonia xenoplax on the growth of concord grape. Journal of Nematology 9: 215-217.  Shaffer, R., T.L. Sampaio, J. Pinkerton, and M.C. Vasconcelos. 2004. Grapevine rootstocks for Oregon vineyards. Publication EM 8882. Oregon State University Extension Service, Corvallis.  Strik, B.C. 2006. Growing Grapes in Your Home Garden EC 1305. Extension Service, Oregon State University. http://extension.oregonstate.edu/catalog/html/ec/ec1305/ Accessed May 10, 2009.  63  Vrain T.C. and J.M. Yorston. 1987. Plant-parasitic nematodes in orchards of the Okanagan valley of British Columbia, Canada. Plant Disease 71: 85-87.  Winkler, A.J., J.A. Cook, W.M. Kliewer, and L.A. Lider. 1974. General Viticulture. University of California Press, Berkeley.  Wittneben, U. 1986. Soils of the Okanagan and Similkameen Valleys, Report no. 52, British Columbia Soil Survey, British Columbia Ministry of Environment.  Yamashita T.T. and D.R. Viglierchio. 1986.The behavior of nonfumigant nematicide stressed, unstressed and wild populations of Pratylencus vulnus cultured on grapevines and bean plants. Revue Nématol. 9: 267-276.  64  4. Conclusions 4.1 Research conclusions As observed in the in-field vineyard trials, there were various benefits of compost application on the free-living nematode community. As hypothesized, various nematode indicators of food web enrichment and enhanced nutrient turnover increased in compostamended soil relative to fertilizer-treated soil. These results are similar to previous studies involving surface application of organic amendments to the root zone of perennial crops (Forge et al., 2003, 2008; Nahar et al., 2006). The changes in nematode community structure were not long-lasting, however; all major trophic groups were significantly more abundant in compost-amended soil six months after the last compost application. Only fungivores were greater at one year after the last compost application, and no trophic groups were significantly greater at eighteen months after the last compost application. These results indicate that the cumulative benefits of three years compost application, with respect to enhancement of the soil food web, are detectable for only about one growing season after the applications cease. .  As hypothesized, the abundance of nematode indicators of soil food web structure (predacious and omnivorous species) also increased with compost applications but as with bacterivores and fungivores, the effect of compost did not persist beyond the first growing season after the last application. Omnivorous and predacious nematode populations were significantly higher under compost treatments at the first sample date only. This could be the result of increased abundance of microbivorous nematodes which would be a food resource for predacious nematodes. Alternatively, compost applications may have induced changes in soil physical and chemical conditions that were more favourable to the omnivores and predators. Most omnivores and predators are members of the Dorylaimida, which are notoriously sensitive to soil physico-chemical conditions.  There were no significant outcomes to the Structure Index although the Shannon Index was consistently higher in the compost treated plots. The Structure Index gives a greater weighting to higher trophic level nematodes therefore an increase in Shannon Index but not Structure Index suggests that the compost may have fostered a greater  65  diversity of bacterivore and fungivore nematodes which would have minimized any effect of increases in diversity of higher c-p ranked nematodes.  As the described effects of compost application were mostly significant in the first six months after the amendment was applied, this suggests that there is no “legacy” effect of the previous yearly compost applications. The South Okanagan has very sandy soils, very hot temperatures in the summer and the compost is applied as a top dressing and not incorporated into the soil. Potentially, some of the organic matter may decompose in the high summer temperatures and regular irrigations regime which would limit the longer term effects of the amendment.  In contrast to our working hypothesis, M. xenoplax and Pratylenchus spp. populations were higher under the compost treatments. Similarly, plant parasitic nematode populations were observed to increase under compost applications in a study by Forge et al. (2005). It was concluded that the compost applications improved soil nutrient and moisture conditions thereby increased general root and plant health and therefore were able to sustain higher levels of the plant parasitic nematodes.  Plant parasitic populations (M. xenoplax, Pratylenchus spp. and Xiphenima spp.) observed in the vineyards were close to or above threshold population levels suggested by McKenry (1992) for damage to grapevines. These threshold levels were deduced in a California study and may not be applicable to Okanagan strains of the nematodes but give indication of population levels and potential to cause damage.  M. xenoplax was found to have negative impacts on self-rooted grapevine growth parameters only. Other studies have concluded that M. xenoplax causes damage to grapevines (McKenry et al., 2001; Pinkerton et al., 2004). In the small-scale microplot trial, M. xenoplax had detrimental effects on plant growth parameters, after two years of growth, with lower prune weight and stem diameters of plants with plant parasitic nematode pressure.  As hypothesized, the rootstock varieties were observed to be more tolerant of nematode feeding. M. xenoplax was only observed to negatively impact the growth of self-rooted vines in the large microplot study but, as it takes time for the population  66  levels to increase to damaging levels, corresponding effects on the growth parameters of the various rootstocks may not be significantly impacted until two or more years into the experiment (as seen in the small-scale microplot trial). Two of the rootstocks were previously shown to be very susceptible to M. xenoplax damage (Pinkerton et al., 2005) although it may take more time and higher parasite populations in our trials to have significant impacts on growth parameters. The large-scale microplot study will continue for subsequent growing seasons so impacts of M. xenoplax on the various rootstocks will be measured and analyzed. Currently, the large-scale microplot study is the only research project specific to plant parasitic nematodes on grape rootstocks in B.C.  Overall, these studies show that the plant parasitic nematode, M. xenoplax, is damaging to establishing grapevines and decreases overall plant growth, especially after two years of vine growth. Our studies also show that amending a very sandy soil with compost has beneficial effects on the free-living nematode community, but the effects do not persist for more than one growing season after compost applications cease. Compost application also resulted in higher populations of plant parasitic nematodes which may not necessarily be detrimental to the vines if the plant nutrient status has been improved and the root system is able to withstand more feeding by the parasitic nematodes. Soil amendments such as compost, although not a control for plant parasitic nematode populations, have the potential to offset the impacts of plant-parasitic nematodes damage so should be employed as a management practice. 4.2. Strengths and weaknesses of the thesis research There were many strengths of the thesis research. The greatest strength and reason that this research is unique is because compost applications were modest, surface-applied and at rates that were tied to comparable fertilizer nitrogen inputs in commercial Okanagan vineyards. Another important strength is the nematode community portion of the thesis research project was located within working vineyards. The research was linked in with an ongoing field experiment, in a real working vineyard so the resultant data are very representative of a ‘conventional’ producing vineyard as opposed to a greenhouse trial or other very controlled environment.  The microplot trials were close to the environment of an in-field trial as the pots were sunk into the ground, backfilled with the native soil and otherwise managed with  67  industry standard practices. Because of this and because the research is ‘local’, results of the research and any proposed management practices would be more likely adopted by vineyard producers in this region. The outcomes of these trials could potentially be adopted by other woody perennial producers in the area such as orchardists.  The research is actively determining aspects of the pathogenicity of a plant parasite (M. xenoplax) that has been until recently overlooked but potentially could be causing detrimental damage to vines and therefore economic losses.  A weakness of the research is that we only sampled four dates in the in-field vineyard trial so were not able to make inferences regarding the ‘within’ year dynamics of the specific nematode populations. Another weakness is that our inoculations with Pratylenchus were not successful. In both experiments, we did not adequately determine if the lack of establishment of Pratylenchus was due to low inoculum densities or because grape is not a good host for the population of Pratylenchus used in our studies. 4.3. Recommendations for future research The extent of ring nematodes in the Okanagan Valley, in vineyards or otherwise, is unknown. M. xenoplax was overlooked in surveys of Okanagan vineyards before 2005 (Graham et al., 1988) most likely because nematode extraction methods previously employed were inefficient. Although a structured survey of vineyards in the Okanagan has not been carried out, M. xenoplax was found to be widely distributed among Okanagan orchards in the late 1980s in a survey by Vrain and Yorston (1987). A survey of M. xenoplax population levels in various perennial crop systems would be highly beneficial to provide a scope of infested vineyards and potential damage. As well, a survey as to where M. xenoplax populations reside in the soil profile would be helpful in determining where that particular species is bioactive.  The thesis research showed variations in plant parasitic nematode populations through time and from plot to plot and indicated a better understanding of sampling programs is needed. Population dynamics would act as the drivers taking into account temperature, host plant physiology, and irrigation regimes so that sampling protocols could be determined to gather the best estimate of nematode populations.  68  An extension of the rootstock trial to include a compost application would be helpful in determining if plant parasitic nematode populations, under compost, on selfrooted vines and various rootstocks still have detrimental effects even though soil health is increased and root growth enhanced. 4.4. Overall contribution of the thesis research to the field of study Little research has been done on nematode communities living vineyards in Okanagan vineyards. This study will ‘get the ball rolling’ and create awareness of plant parasitic nematodes, which otherwise have been overlooked in vineyard management because they do not cause specific above ground effects but decrease overall vine vigour and productivity. The in-field compost trial will give grape producers information as to the benefits of compost application and the positive effects on the free-living nematode community. Applications of compost would result in more sustainable production and soil management and potentially decrease the use of chemical fertilizer.  The rootstock trial, although in its infancy may give grape producers a solid cultural management practice as chemical means of controlling plant parasitic nematodes (soil fumigation before planting or replanting) are progressively being taken off the market. This study contributes to rootstock research that is going on elsewhere in the Pacific Northwest and is very beneficial to grape growers and perennial fruit production systems to be aware of the potential pathogenicity of at least one lesser known (and lesser studied) plant parasitic nematode, M. xenoplax.  Pratylenchus spp. inoculation in the small microplot study did not establish and although it has been observed in the large microplot study in small populations, further research needs to be done in the assessment of this plant parasitic nematode on grape vines, due to its abundance in Okanagan vineyards and potential to cause damage. 4.5. Potential applications of the research findings As the compost research took place as in-vineyard field trials, the potential for vineyard producers to apply the results is promising. The research findings conclude that the use of compost is beneficial so growers will be urged to use compost as a part of sustainable management.  69  If producers are observing unthrifty vines and unproductive areas, it will be recommended that they have their soils analyzed for plant parasitic populations. As well, use of sucrose centrifugation extraction method (Forge and Kipinski, 2008) can be employed to increase extraction efficiency for local plant parasitic nematodes, in particular ring nematodes. 4.6. Future research directions in the field Future research directions related to this research would entail doing a survey of Okanagan vineyards for ring nematodes to determine present population levels. Pathogenicity research on location specific ring nematode species would add to the little information that is available and give local producers an idea of what they are dealing with in terms of levels of damage. Research is needed to assess the effect of water management (deficit irrigation as an example) on ring nematode populations and specific rootstocks.  Lastly, future research projects could assess seasonal population dynamics of ring nematodes that would offer information regarding sampling strategies and scheduling. Observed variations through time and plot to plot differences indicate that we need to have better understanding of sampling programs. These may be dependant on pathogen lifecycle, climatic factors such as temperature and precipitation, host plant physiology, and irrigation regimes.  70  4.7. Literature cited  Forge, T.A and J. Kipinski. 2008. Nematodes. In: Carter, M.R.and E.G. Gregorich (eds.), Soil Sampling and Methods of Analysis. CRC Press, Boca Raton, FL, pp. 415-425.  Forge, T.A., S. Bittman, and C.G. Kowlenko, 2005. Impacts of sustained use of dairy manure slurry and fertilizers on population dynamics of Pratylenchus penetrans under tall fescue. Journal of Nematology. 35:207-213. Forge, T.A., E. Hogue, G. Neilsen, and D. Neilsen. 2003. Effects of organic mulches on soil microfauna in the root zone of apple: implications fro nutrient fluxes and functional diversity of the soil food web. Appl. Soil Ecol. 22:39-54. Graham, M.B., B.A. Ebsary, T.C. Vrain and J.M. Webster. 1988. Distribution of Xiphinema bricolensis and X. pacificum in vineyards of the Okanagan and Similkameen valleys, British Columbia. Can. J. Plant Path. 10: 259-262.  McKenry, M.V. 1992. Nematodes. Pp. 281-293 in D.L. Flaherty, L.P. Christensen, W.T. Lanini, J.J. Marios, P.A. Philips, and L.T. Wilson, eds. Grape pest management. 2nd ed. Publication No. 3343. Oakland, Ca : Division of Agricultural Science, University of California.  McKenry, M.V., J.O. Kretsch, and S.A. Anwar. 2001. Interactions of selected rootstocks with ectoparasitic nematodes. Am. J. Enol. Vitic. 52:304–309.  Nahar, M.S., P.S. Grewal, S.A. Miller, D. Stinner, B.R. Stinner, M.D. Kleinhenz, A. Wszelaki and D. Doohan, 2006. Differential effects of raw and composted manure on nematode community, and its indicative value for soil microbial, physical and chemical properties. Appl. Soil Ecol. 34: 140–151.  Pinkerton, J.N., R.P. Schreiner, K.L. Ivors, and M.C. Vasconcelos. 2004. Effects of Mesocriconema xenoplax on Vitis vinifera and associated mycorrhizal fungi. Journal of Nematology 36: 193-201.  71  Pinkerton, J.N., M.C. Vasconcelos, T.L. Sampaio, and R.G. Shaffer. 2005. Reaction of Grape Rootstocks to Ring Nematode Mesocriconema xenoplax. Am. J. Enol. Vitic. 56:377-385. Vrain, T.C. and J.M. Yorston, 1987. Plant parasitic nematodes in orchards of the Okanagan valley of British Columbia. Plant Disease. 71: 85-87.  72  Appendices Appendix 1. Plot plan for Tennant’s vineyard (in-vineyard compost trial) Tennants Project 20 site 2 Black Hills Winery - Lower slope  Winery building  g g g g g g g g g g g g g g g g g g g g g g g g g g g g g  g  row# (trt #) 107 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 1 1 (1) 2 (4) 3(3)  g  plot #  rep#  2  N 3  4  5  6  7  8  108 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 6 (5) 5 (6) 4 (2)  g  109 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 7 (5) 8 (1) 9 (3)  g  110 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 12 (4) 11 (2) 10 (6)  g  111 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 13 (2) 14 (3) 15 (5)  g  112 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 18 (6) 17 (4) 16 (1)  g  113 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 19 (3) 20 (6) 21 (2)  g  114 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 24 (1) 23 (4) 22 (5)  g  115 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 25 (4) 26 (3) 27 (2)  g  116 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 30 (5) 29 (6) 28 (1)  g  117 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 31 (3) 32 (1) 33 (2)  g  118 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 36 (5) 35 (6) 34 (4)  g  119 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 37 (2) 38 (3) 39 (5)  g  120 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 42 (6) 41 (4) 40 (1)  g  121 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 43 (1) 44 (6) 45 (3)  g  122 g C C C C C C C C g g C C C C C C C C g g C C C C C C C C 48 (5) 47 (4) 46 (2)  g  g g g g g g g g g g g g g g g g g g g g g g g g g g g g g  g  house  Treatments 1 white - low N early (40kg N/ha -bud break) 2 orange - high N early (80 kg N/ha - bud break) 3 yellow - low N late (40 kg N/ha - bloom) 4 red - high N late (80 kg N/ha - bloom) 5 blue - low N late (40 kg N/ha bloom) + post harvest 6 green - compost  g = guard vine C = Cab. Sauvignon  73  Appendix 2. Plot plan for Bullpine vineyard (in-vineyard compost trial) Project 20 Site 1 Vincor Bullpine Vineyard northeast corner of block G  g = guard vine M = Merlot 181/SO4  g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g  8g  M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g  48 (2)  47 (3)  46 (5)  45 (1)  44 (4)  43 (6)  row/rep#  7g  M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g  37 (4)  6g  2g  35 (5)  34 (6)  33 (3)  32 (1)  31 (4)  26 (5)  27 (2)  28 (4)  29 (1)  30 (6)  23 (5)  22 (1)  21 (3)  20 (4)  19 (2)  14 (2)  15 (3)  16 (6)  17 (4)  18 (1)  M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g  12 (6)  1g  42 (5)  M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g  13 (5)  N  41 (3)  M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g  24 (6)  3g  40 (6)  M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g  25 (3)  4g  39 (1)  M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g  36 (2)  5g  38 (2)  11 (3)  10 (2)  M M M M M M M M g g M M M M M M M M g g M M M M M M M M  1 (5)  2 (6)  3 (4)  9 (4)  8 (5)  7 (1)  g g M M M M M M M M g g M M M M M M M M g g M M M M M M M M g 4 (1) 5 (2) 6 (3)  g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g g  plot #  (trt #)  Treatments 1 white - low N early (40kg N/ha -bud break) 2 orange - high N early (80 kg N/ha - bud break)  3 yellow - low N late (40 kg N/ha - bloom) 4 red - high N late (80 kg N/ha - bloom)  5 blue - low N late (40 kg N/ha bloom) + post harvest 6 green - compost  74  Appendix 3. Preliminary microplot trial – PARC - Summerland  south  12c  21m  30p  11m  20c  29m  10p  19p  28c  9m  18c  27c  8p  17m  26p  7c  16p  25m  3p  6c  15c  24m  2m  5p  14m  23c  1c  4m  13p  22p  M= M. xenoplax P= Pratylenchus spp. C= Control  75  Appendix 4. Grape Rootstock/Ring nematode microplot trial – PARC - Summerland SouthWest B1  B2  B3  B4  B5  B6  B7  B8  B9  B10  8  16  6  13  17  16  2  18  12  5  7  16  5  3  12  2  18  15  16  15  11  10  14  2  1  4  13  16  12  8  15  9  8  5  3  11  11  2  5  3  7  4  5  17  3  5  7  9  4  15  17  8  6  1  16  14  7  9  8  2  18  13  16  5  11  13  4  10  11  3  1  4  15  14  17  10  4  14  12  9  3  10  18  14  14  9  10  13  10  2  3  13  12  18  3  6  10  8  17  5  12  6  7  12  10  18  17  7  18  5  14  13  16  1  6  7  1  13  8  16  2  9  15  11  6  15  4  16  14  1  6  10  2  4  14  11  4  5  7  14  3  9  6  9  8  3  15  9  17  6  2  12  2  7  18  18  15  6  10  17  12  1  11  8  12  13  1  18  11  8  17  11  7  15  9  13  1  17  4  1  SouthEast  Code  Rootstock  Nemas  1 2  Self-root Self-root  none Mx  3 4 5  Self-root Self-root Riparia Gloire  Pp Both none  6 7 8  Riparia Gloire Riparia Gloire Riparia Gloire  Mx Pp Both  9 10 11  3309 3309 3309  none Mx Pp  12 13  3309 44-53  Both none  14 15 16  44-53 44-53 44-53  Mx Pp Both  17 18  VB9/Self VB9/44-53  none none  Mx = M. xenoplax Pp = Pratylenchus spp.  76  

Cite

Citation Scheme:

        

Citations by CSL (citeproc-js)

Usage Statistics

Share

Embed

Customize your widget with the following options, then copy and paste the code below into the HTML of your page to embed this item in your website.
                        
                            <div id="ubcOpenCollectionsWidgetDisplay">
                            <script id="ubcOpenCollectionsWidget"
                            src="{[{embed.src}]}"
                            data-item="{[{embed.item}]}"
                            data-collection="{[{embed.collection}]}"
                            data-metadata="{[{embed.showMetadata}]}"
                            data-width="{[{embed.width}]}"
                            async >
                            </script>
                            </div>
                        
                    
IIIF logo Our image viewer uses the IIIF 2.0 standard. To load this item in other compatible viewers, use this url:
http://iiif.library.ubc.ca/presentation/dsp.24.1-0067730/manifest

Comment

Related Items