Open Collections

Hrycan, Jared

University of British Columbia

Young vine decline (YVD) fungal pathogens cause internal necrosis, leading to stunted growth and eventual plant mortality within the first few years after planting. Canada’s fast-growing grape and wine industry depends on the import of nursery propagated material but the health status of ready-to-plant nursery grapevines in Canada regarding YVD fungi is unclear. A nursery survey was conducted to investigate the presence or absence and quantity of the most prevalent YVD pathogens reported in other countries. 99% of plants contained at least one YVD pathogen, and overall, a mean of 3 YVD fungal species were found in each grapevine. Pathogen abundance for each fungus in single plants was conducted using droplet digital PCR. Results showed fungal abundance to vary widely between nurseries, grapevines, and different parts of the same grapevines. Additionally, several YVD pathogens were isolated that had not previously been reported in Canada, showing that nursery material can be the source or new fungal pathogens in Canadian vineyards. Phaeomoniella chlamydospora (Pc), one of the main agents of the YVD Petri disease, was found in up to 80% of ready-to-plant nursery grapevines. The presence of Pc in asymptomatic nursery grapevines has led to the hypothesis that it may be a latent pathogen, transitioning from an endophyte to a pathogen under plant stress. Two greenhouse and four field experiments were conducted to determine the effect of water stress, heat stress, j-rooting, and ring nematode infestation on Pc abundance and disease development in young grapevines. Arbuscular mycorrhizal (AM) fungi were inoculated in the greenhouse to investigate whether a reduction in plant stress due to AM fungal colonization would reduce Pc abundance. In the greenhouse, a combination of water stress and AM fungal colonization increased Pc abundance. Young vine decline like symptom development was observed in the field and higher mortality occurred in grapevines subjected to the 50% water treatment compared to plants subjected to the 100% water treatment. Ring nematode infestation increased Pc abundance in the greenhouse in AM inoculated plants compared to nematode negative AM inoculated plants. In the field, plants inoculated with 5,000 Pc spores that were inoculated with ring nematodes had higher overwinter mortality than nematode negative 5,000 Pc inoculated plants These findings suggest a relationship between plant stress, Pc abundance, and subsequent disease development in young grapevines within a few years after planting.

Text; Dataset

2024-07-17

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/88650

Biology

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/