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The effect of type of cutting, growth regulating substances, and rooting media, on the vegetative propagation… Denby, Lyall Gordon 1950

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THE EFFECT OF:TYPE OF CUTTING, , GROWTH REGULATING SUBSTANCES, AND ROOTING MEDIA; ON THE VEGETATIVE PROPAGATION OFrOAMELLIAAJAPONIOA; by Lyall Gordon Denby* -0-A Thesis .submitted! i n Partial Fulfilment. of The Re quirement s r for the: Degree? of MASTER OF SCIENCE IN AGRICULTURE' initheftDepairtmenth ofT HORTICULTURE". THE UNIVERSITY OF BRITISH COLUMBIA April, 1950. fj To /9V THE EFFECT OF TYPE OF CUTTING,  GROWTH REGULATING SUBSTANCES, AND ROOTING:-MEDIA, ON'THE VEGETATIVE PROPAGATION OF CAMELLIA JAPONICA. by Lyall Gordon iDenby ABSTRACT OF A Thesis^submitteddin Partial Fulfilment of The-Requirements for the Degree: of-MASTER OF SCIENCE IN AGRICULTURE in the Department I of HORTICULTURE. THE UNIVERSITY OF BRITISH COLUMBIA April, 1950. - 1 -THE EFFECT OF TYPE OF CUTTING,  GROWTH REGULATING SUBSTANCES, AND ROOTING MEDIA,  ON THE VEGETATIVE PROPAGATION OF CAMELLIA JAPONICA. ( Abstract) Lyall Gordon Deriby. The work in connection with this Thesisr-wae undertaken to devise ways^  of improving the technique of propagating Camellias from cuttings. The* inclusiomof a review of literatureepertaining to those factors-which influencecthe rooting of cuttings^ was intended primarily/to focus the experimental work onto specificoaspects«of the problem. . In the first" experiment, a comparison was made betweemthe response of .leaf-bud cuttings and stem cuttings of Camellia "Donckelari", to treatment with Rootoney (a commercial plant hbrmoneopowder containing naphthyl acet amide •= as the growth' substance). The results indicate that thes superior root :,system developed^ by the untreated stem cuttings, (evidenced! by more durable and-'more compact roots), more than^offsets the advantage-of a slightly higher rooting percentagecobtained through the application) of Rootone. This was not taken to mean that better or significantly/faster rooting may not result -from the use of root-inducing substances oni cuttings* of varieties which aresmuch slower or more difficult to root than is the:-, variety used in this experiment:. The use of Root one on leaf-bud cuttings of this same variety resulted^ in severer-loss through^the death of the; axillary buds. The evidence suggests that .better results-could be expected'! i f no hormone applications were made on leaf-bud cuttings of varieties^ which are rooted as-easily ,;as is =Donckelari, and that, with moreedifficult, subjects, a less concentrated-hormone application 'would probably be safer. A second 'experiment was conducted'to determine the valuevof Terras-Lite) :(a°horticultural grade of vermiculite), in rooting media for the? propagation iof Camellia cuttings. .The results indicate that a mixture? of 2 parts sand, 1 part Terra^Lite, and 1 part peat (by volume), is superior to the medium generally used, and consisting of sand and peat olyi This-superiority was evidenced by a higher rooting percentage, sturdier, more:.? compact roots, and reduced loss from-disease and drying out. A third experiment was designed to determine the response of threes distinct' types of cuttings to treatments with Root one, and<Terenox< and: Copper A pre-rinsertionidips ^ alone and in combination i with the Root one. . The results indicate that the first typeof cutting,, (which consisted of the basal portionnof the stem of the ripened growth of the current,seasom together withnthe first leaf and its axillary bud), was definitely pre-disposed against rooting. The second-type of cutting, (consisting of thee apical bud, first leaf and axillary bud, and the stem portion* down to but not including the secondHleaf and bud,' a l l of the new shoot), and. the.: third type,; (each of which consisted-of one leaf and axillary bud takem from a positionnon the' new shoot^ intermediates between the basal and-apical leaves^ and including the entire stem in the immediate:proximity of the :bud), .rooted well enough to be of practical value. The former rooted''at least as readily as^ -do ordinary stem cuttings, and are'much less demanding on the stock plant..; the latter have the advantages'1 of the leaf-budr cuttings in that they are economical where>•:cutting -material is very limited^ andf according to the results-of this experiment, have the added advantage of being much less-susceptible to die-back of the all-important axillary bud. With both types of cuttingB, Rootone alone gave no increase in rooting over no treatment, and with the modified-leaf-bud or Type III - 5 -cuttings?;seemed to have a marked-inhibiting effect on the sprouting of the axillary bud, The-combination;of the Perenoxxdip andrRootonertapplicatiom gave results "that were markedly superior-to those of any other treatment, re percentage rooting? and faster and better rooting. In addition? the; Typeelll cuttings-given this combination treatment^evidencedno inhibition of the axillary bud, and ultimately, of the new shoot.-The• Copper A treat-ment, alone, :gave;unsatisfactory results? but i n combinatmbmwith Rootone, indicated :that i t might give better,.thoughhslower, ;rooting response? than did .'Rootone i t s e l f . . ACKNOWLEDGMENTS. Thecauthor wishesfto thank cDr. G. H. Harris?: Professorr of Horticulture-(Plant Nutrition), under whose guidanoeethe: work -was? conducted? , for his kind: and'.valuablea assistance. Gratefullacknowledgment is also given to Dr. A. F. Barss? Professor and Head of theeDepartment of Horticulture? for his kindly-interest showm throughout^ the progress: of this: work. TABLE OF CONTENTS'* Page:* INTRODUCTION-; 1 A BRIEF REVIEW OF LITERATURE PERTAINING TO THE FACTORS I INFLUENCING :;THE ROOTING OF CUTTINGS' 2" I . FACTORS RELATED TO THE SELECTION7OF THE CUTTINGS: 1. Age:, of the Wood . 5 2. Time of Year at .which Cuttingss-areeTakem 5 5• Vigor of the Cuttihgs-.... • 5f 4. Type- of Cutting 5 5. Varietal Differences' • • 5 II. .FACTORS RELATED TO THE HANDLING OF THE CUTTINGS: 1. Humidity 61 2. Temperature 7 5. Light Intensity and Shading- 7' '.. TheeGlenn-rDaler-Propagator 8 4. ,Nature:.of the Rooting Medium: 8 5. Prevalence of .Disease Organisms 11 III. CHEMICAL MEANS OF.INDUCING OR HASTENING;ROOT-INITIATION: 1. Application-of-Hormones - 1^ 2. .Useeof Fungicidal Dips^ l4 OBJECTS OF THE EXPERIMENTS l6i EXPERIMENT I - "COMPARISON OF RESPONSE OF LEAF-BUD AND STEM CUTTINGS-TO TREATMENT WITH ROOT ONE" 18 1. Materials and Methods'- 18 2. Results and Observations- 19 5. Discussion... 21 4. . Conclusionss 24 EXPERIMENT II - "TO DETERMINE THE VALUE OF VERMICULITE IN ROOTING MEDIA''FOR THE PROPAGATION OF CAMELLIA CUTTINGS" 26 1. Materials and Methods" •••• 26 2. Results and Observations 27 5. Discussion • 28 4. Conclusions • •• 5° Paget EXPERIMENT III * "RESPONSE OF VARIOUS TYPES OF CUTTINGS TO TREATMENTS WITH ROOTONE AND FUNGICIDAL DIPS, IN THE PROPAGATION OF CAMELLIA'. DONCKELARI11 51 1. Materials and Methods jjl 2. Results and Observations 55 5« Discussion:: 56 4. Conclusions;... 40 SUMMARY ^ 42"? REFERENCES CITED 4^  LIST OF TABULATIONS. 1. TABLE TO SHOW RESPONSE OF LEAF-BUD AND STEM CUTTINGS TO TREATMENT WITH ROOTONE 19 2. TABLE TO SHOW EFFECT OF VARIOUS MEDIA ON ROOTING. RESPONSE OF CAMELLIAS 27 Ji- .TABLE TO SHOW RESPONSE OF DIFFERENT TYPES OF CUTTINGS' TO TREATMENT WITH ROOTONE AND FUNGICIDAL DIPS _ 55 LIST OF ILLUSTRATIONS. 1. SKETCHES TO ILLUSTRATE THE DIFFERENCES IN RESPONSE BETWEEN STEM AND LEAF-BUD CUTTINGS, TO TREATMENT WITH ROOTONE. 20 2. SKETCHES TO ILLUSTRATE TYPES OF ROOT FORMATION: EVIDENCED IN VARIOUS MEDIA..... 29 5. SKETCHES TO ILLUSTRATE THE THREE TYPES OF CUTTINGS USED, AND THEIR TYPICAL RESPONSE TWO MONTHS AFrER TREATMENT WITH ROOTONE AND PERENOX (Expt. I l l ) 55 THE-EFFECT OF :TYPE OF: CUTTING,. GROWTH REGULATING SUBSTANCES, AND ROOTING :MEDIA» ON THE VEGETATIVE PROPAGATION OF CAMELLIA JAPONICA1. INTRODUCTION*'; The;; comparatively/recent revival of interest im Camellias, whi dr-ied; to the organization) .inrl9^5:», ofr the; Americam CamelliarSociety,; is? indicative that theseeplants will soon attainntheir deserved place in: the hearts and gardens of America* Despite -the fact.that the greater part of Canada 1B-situated too far North for out-door: cultures of Camellias,,there/is no^reasomwhy they shouldfnot become just as popular here as they areebecoming in. the United States* for they are admirably suited to indoor .and conservatory/cultures Innthe southerm coastal regionaof British Columbia^, manyy Camellia varietie grow and flower very satisfactorily, provided that certain simple pre-cautions are taken to ensure ^maximum hardiness. However, before theses plants can become as popular and aeswidely planted as they should Canada, their cost must come down to within the reach of more amateur gardeners* This in turn simply means that locally propagated plants-must be grown, to undercut the expense of importing. During the past tento fifteen years, great advances have been, made in the field of ..plant propagationrifrom cuttings. .Our knowledge in this regard is s t i l l increasing by leaps and bounds, but even now, the pointt has been reached where the development of a cutting technique which would prove reliable and satisfactory for the propagation of most hybrids of Camellia japonica, may be anticipated. A BRIEF REVIEW OF LITERATURE PERTAINING TO THE FACTORS INFLUENCING THE ROOTING OF CUTTINGS. Cuttings of most Camellias will root eventually, provided:that ideal conditions for rooting are painstakingly maintained until rooting has been accomplished. Generally,- a large percentage of the cuttings f a i l to root, because the Camellia, being a broad-leafed evergreen, is more fast-idious in respect to the maintenance_of these ideal conditions than are most plants. The problem is to overcome this difficulty, either by devising a technique whereby ideal conditions can be maintained vrith a decided degree of certainty for as long a period as is necessary, or by hastening the normal rate of rooting so that the cuttings will become independent before they can succomb to slight disadvantages of environment. At least a brief review of the factors which influence the likelihood; that a given group of cuttings will root,,or "take", and the rate at which the rooting may be expected to take place, seems essential to the under-standing of the complexity of the problems involved* At the same time, inclusion of references to at least some of the better work done in each field should be helpful in focussing subsequent experimental work in this thesis onto specific aspects of what constitutes a very wide and complex problem. The factors of greatest importance in their influence on the rooting of cuttings, can be divided into three main groups, as follows: I. Factors related to the selection of the cuttings. II. Factors related to the handling of the cuttings.. III. Chemical means of inducing or hastening root-initiation. Each of the above is discussed in turn in the following text. I. FACTORS RELATED TO THE SELECTION OF THE CUTTINGS. 1 . Age.of theWood: Workers are agreed!that, with the Camellia, only wood of the current season's growth, i.e. wood that iB less than one year old, tends to root; satisfactorily or quickly enough to be practical ( 8} 15 ). 2. Time of Year at Which Puttings are Taken: actual practice, i t has been found-that cuttings of Camellia japonica? i f handled:correctly, will eventually form roots, regardless; of the time of year at which they are takemjit is generally/ accepted that response is more rapid and more certainif the cuttings are taken during the optimum period ( 15 ). This period varies with varieties; and growing conditions, but in general extends from early July to early/ September..It may be the period following cessation of the first flush of growth,; when the new growth has ripened to the point that its color is beginning to change fromrbright green to light brown; (8). 5.-Vigor of the Cuttings: Generally, i t is accepted that wood of fairly vigorous to vigorous most suitable for cuttings. However, some workers: (16) claim; that very vigorous wood is not suitable, and that with Rhododendrons andi Camellias, very thick cuttingssare slow to root.. 4, .Type of Cutting'. There is considerable variancecamong thecdifferent genera-and species; of plants, in response to the type of cutting used and the region from/ which i t is made (18; 15 pg.-98). With Camellia-japonicay the usual type of cutting is the stem cutting, consisting of growth ofithe current ^ season, taken after length growth, has ceasediand the wood has begun to ripen,; and cut .at the junction of the current and' previous season'iB wood; Usually, even i f laterals aree used for cuttings, rno heel i s taken} Hanger (8) statesrthat he finds i t advantageous to leave a heel attached*• I n 1 the few years closely following the:work of Skinner i n 1959 (20), i n which he introduced the leaf-bud cutting as a promising method for propagating Rhododendrons, extensive work has been doneto adapt the-.: method to Camellia propagation ;(8; 25$ 26} 29)» The leaf-bud cutting consists of the entire leaf, lamina and petiole, together with the axillary bud* A shieldr-shaped portiomiof the bark and wood:is removed with the bud,, exactly as i t would be i n the preparation of buds ;for shield budding. Thes cuttings are inserted i n the medium, deeply enough to cover the bud, and usually theyetiole, but i t i s not considered:;wise, to insert them-; deeply enoughito cover a great deal of the leaf i t s e l f . . I n most cases i t has been found that, although'the method i s promising, with Camellias some d i f f i c u l t y i s usually encountered:.when the bud on the cutting f a i l s to sprout into vegetative growth. Skinner (20) enountered similar d i f f i c u l t y / i n securing satisfactory shoot growth from rooted Rhododendron cuttings. WithiCamellia leaf-bud cuttings, this reluctance of theobud to shoot into vegetative, growth i s apparently caused at times by damage incurred by the bua innthe process of preparation of the cutting, at other times by damage to the: bud caused by root-inducing hormones when these are applied,.particularly i f these are applied i n the liquid form (29)» but most frequently, growth of the bud i s arrested* and the bud i t s e l f i s killed*.by the action ;of fungus diseases. Workers who have experimented with Camellia leaf-bud cuttings seem - 5 -to be agreedithat development of a saleable plant from a leaf-bud cutting is slower than from a larger stem-cutting,.but a l l believe that, perfected, the method could be practical where cutting material is limited? as i t so often is in cool Northern regions where seasonal growth is not great, and in a l l regions with the newer and rare varieties. There are other possible types of cuttings which could be devised? which might show distinct advantages;over types -at present popular. Partial stem cuttings, from apical, ;basal, or intermediate sections of the shoot, and consisting of single or multiple bud nodes? for example, might constit-ute a means of improving the cutting technique. As far as can be ascertained no work has as yet been done in this regard, with Camellias,. 5 » Varietal Differencesv Throughout the genus Camellia? there is considerable variance among the.species?,in the ease with which their cuttings form;roots. According to Hanger (8), Camellia salueneis and its hybrids seem to root most depend-ably and most rapidly. Camellia sasanqua is also quite easy, followed by Camellia japonicaeand its hybrids..Camellia oleifolia and C. taliense are; more difficult, and slower, while the garden form of C. reticulata is conceded to be the most difficult of a l l . This difference between species; is of considerable importance because many of the new hybrids:; of C.japonica (the most important source of garden hybrids), consist of crosses with these other species. Even among the hybrid varieties of C. japonica,.there-is great divergence in ability to root from cuttings..Hyatt (14) lists Debutante, Christine Lee? Sarah Frost, and Duchess of Sutherland as varieties which: root consistently well and rapidly under ideal conditions. He states that on the other hand, such varieties as Mathotiana, Alba Plena, and Daikagura? - 6 -can be depended:!uponvto respond slowly, and to be consistently difficult*. This factor alone is a source of considerable worry to growers? and accounts to a considerable extent, for the divergence in price that exists between the varieties. II. FACTORS RELATED TO THE HANDLING OF THE CUTTINGS. Factors;pertaining to the environmental conditions to which the cuttings are subject, markedly influence?the degree of success that can be expected in the survival, rooting and ultimate growth of these-cuttings.• The Camellia,,being a broad-leafed evergreen, is fastidious in its^ demands in regard to the following environmental factors: 1. Humidity: It is very important that a high humidity be .maintained! around the-, cuttings at a l l times? to prevent wilting until roots, which would enable: the cutting to resume an independent existence? are established. Thesmainr tenance of high humidity can be accomplished by enclosing the cuttings ini an air-tight propagating; frame, and by, frequent, even daily overhead syringing with water at frame temperature. The ease with which high humidity can be maintained?.will be governed of course,,by temperature and light conditions. Recent work involving the use of humidifying or fog nozzles? by means of which cuttings in a frame are subjected to continuous mist (6j 7)» has; indicated-that this development may be of great value in maintaining a super-saturated humidity condition, for the rooting of certain-difficult subjects. - 7 -2. Temperature! For optimum rooting and subsequent shooting, a temperature?.' of 70 to 75 degrees F. seems desirable. This is best supplied" as bottom heat, by-use of thermostatically controlled lead-rcovered soil cable, (8j 12j 24). According to Hyatt (15) and Watkins (26), bottom heat is not necess-ary when Camellia cuttings are taken at their ideal stage of maturity during the summer, but is a tremendous advantage at a l l other, times of the year. Commercial practice: in.iwarm Southern regions entails thee plant-ing of the cuttings in shaded frames, often without glass covering, im the outdoors, and where this is possible,.bottom heat would probably be of l i t t l e or no advantage. It does not seem likely that such a method could ever be applicable to the cool, windy Northern;sections of the Camellia zone*. 3« -Light ^ .Intensity and Shading* Aside from the fact that the higher the light intensity is,, parties ularly i f the frame is exposed to f u l l sunlight, the greater is the care necessary to prevent scorching and drying out, i t has been shown (15 pg 86) that different plant species=root better under varying degrees of shading. The leaves :of the Camellia, being very broad and particularly suscept-ible to scorching, may be damaged byyexposure to the unbrokemrays of the sun for periods even as short as onehourj this is especially/true i f the cuttings are under glass..Mainly for this reason, but also to alleviate the necessity of constant watching and regulation of shades and watering,, most workers shade their frames with slats, whitewash, or better, with} double thicknesses of cheesecloth, or muslin* It seems probable that no set rule could be followed, but that the degree of shading should vary with local weather conditions, and the exposure of the frame. With indoor - 8 -frames, in. greenhouses etc., shading may not be necessary, though.unless;: the house i t s e l f i s shaded? i t w i l l probably be advisable.. The Glenn Dale Propagator: This i s really a greatlyvimprovedd propagating frame? designed and; perfected by Dr. Vernon St out emeyer at the Glenn Dale: Stat iom of the United States Department of Agriculture. ( 25 a.). The unit is;truly revolutionary in;that, by u t i l i z i n g a r t i f i c i a l light as radiated by fluorescent/tubes? i t ^completely obviates the need! of natural light and the di f f i c u l t i e s : o f light intensity and shading connected with it..Being a closed case, ittgreatly f a c i l i t a t e s the maintenance of optimum-humidity , and because i t can be installed! i n : a dark, warm corner indoors, the problems of temperature are also large-ly surmounted.. The development of this propagating case i s a monumental step towards the standardization of environmental conditions so necessary/both i m commercial propagation work, and i n controlled s c i e n t i f i c experiments.. ( The Glenn Dale Propagator has recently appeared on thee r e t a i l market, under the trade-name "Start-A-Plant?, and i s manufactured and sold by St art-A-P1ant Division, ;Carstenite Sales? I65 W. Wacker, Chicago, I l l i n o i s . ) 41 .Nature of the (Rooting;; Medium: Until comparatively recently, the generally; recommended;; medium; for rooting cuttings hasrbeen"clean, sharp sand". (15 pg. 95» 3-5) • Many, propagators s t i l l insist that sand, provided that i t i s clean, sharp,,, and of the right consistency, i s the most practical rooting-medium* In order to obtain the correct air/water relationship i n the medium? size:, of particle i s of utmost importance, coarse sand having too low a capacity for water retentional and fine sand having at times too high a capacity for water retention ando,usually too low an air capacity. In both cases, ,im fact whenever: sand is used alone, wide and oftemrapid fluctuations may result in drying out. Cuttings in such media* iff they are of a typesthat demand a high and constant moisture supply, as do Camellias,,will require: almost constant, vigilance. For cuttings that prefer rather dry conditions* as certainly some do, ;sand is admittedly satisfactory, but for most cuttings:-, better media-have been devised'. -As far back as 1928, Hitchcock advocated^ ] the use of a: mixture. of; sand and peat, as being superior to sand^as a rooting medium for a wide range of plants (°). Most of the recent work with;.Camellia cuttings has been carried out using peat and sand in varying proportions* Hanger (8) recommends 5 parts silver sand to 1 ..part sorbexrpeat; Skinner (20) favors 5 parts New Jersey quartz sand to 2 parts peat moss; Watkins: (26) uses-equal parts sand and peat, and so on. The advantage offthe combination, aside from the acid reaction of the peat, (which would be expected to be. of decided advantage .to acidophiles such as Camellias), seems primarily to be due to its ability to absorb water and so reduce the fluctuations: in the moisture content of the medium* without reducing the air. capacity. It is probable that some of the advantage is due to increased aeration*; because peat decreases the tendancy of the sand to form a crust, which most sands will do i f watered overhead. Kemp (16) mentions that considerableesuccess:hae been attained: at Edinburgh since 1952, using granulated pumice as a rooting medium*.The particles used are about the same size as sand grains, permitting excell-ent aeration*, and in addition, the porosity of the pumice ..particlet enables i t to absorb water like a sponge, so i t does not dry out as does sand* The difficulty, of course, lies in the inavailability of pumice. - 10 -Recently, some work has beenndone to test the efficacy of vermioulite products, alone and in:various combinations with:sand or peat,,as materials: suitable for use as-cutting media*.Friedman (5) gives an excellent account, of the nature, properties? and uses of this sub stance, which", is of value in determining just why i t might be of value for certain purposes• •In 194-7, Sawada (19) conducted! experiments to determine the value of vermi-oulite as a rootingrmediumcin-comparison with sand, peat, and sand-peat mixtures. He.also used!sandrvermiculite mixtures, but because he giveer l i t t l e data on the specific type of vermioulite used, and failed to include mixtures incorporating peat with! sand and vermioulite? i t would: appear that his conclusions that sand-peat mixtures are superior to mixtures containing vermioulite may be subject to some question..Cope (4) conducted! an experiment which indicates that Terra-lite, a horticultural grade of vermioulite, used alone, is superior to sand-peat mixtures for Camellia cuttings, but the reliability of hie results was not enhanced-! by the fact that his check flats, containing, sand and peat, and those containing sand-peat-Terra-lite mixtures, were compacted. .What was proved! to a certainty was that packing has a disastrously; deleterious effect om mixtures; containing vermioulite. The advantages of vermioulite when used1in-cutting media are that i t combines a high moisture capacity with a high porosity, so that i t remains moist for long periods, but i f not compacted, is well[aerated!at al l times..In addition, i t is light in weight, thus facilitating handling, is not too expensive, and is reliably sterile. There are several types of vermioulite available;on the market.-Terra-lite,;being a-fine grade specr ifically designed for horticultural use, has been found to be most suit-able for use in cutting, media. The coarser grades which are designed! primarily for insulation, and the stabilized concretetaggregate, are not. - l i -l t appears that there is s t i l l need: for study in this field,,for results pertaining to the effectiveness of vermiculie products in rooting media and what constitutes theibest combinations, are not, to date, conclusive. 5» Prevalence of Disease Organisms» This factor is rather closely linked with the properties of thea rooting medium, for i t ia through! the medium that most of the fungus diseases which cause serious losses in cutting beds, are introduced. It is unfortunate that the conditions whichhare most ideal for the initiation and development of roots on,Camellia cuttings are also ideal for thee growth of thesecdiseases. The disease most commonly associated withhdie-back or damping off of stem cuttings, is Rhizoctonia (2j), which usually gains entrance into the cuttingvthrough.the damaged tissues-in the region of the cut, and! kills the tissuesj causing them to turmbrown or black, as i t progresses^ upward through the stem. .Eventually, even though the cutting above the level of^ ,he medium-may appear normal and healthy,,the leaves drop off at the slightest touchiWith leaf-bud cuttings, Rhizoctonia is even more: troublesome. Frequently the leaf-petiole:and lower portion of the- leaf itself turn black even before the cutting is callusseii such cuttings: must be removed promptly and destroyed* In other cases, the cutting may root well before the disease becomes evident, but i f the leaf becomes infected beforeethe bud begins to sprout strongly, the chances of survival are negligible. .Most frequently, the only evidence of the disease appearing before thercuttings have rooted well enough to be potted up, be found on the bud itself. Close examination may reveal that, even though! roots, petiole and leaf appear quite normal, the bud itself is blackened, and dead. Such cuttings, i f potted up, .will often f i l l the pot with roots, - 12 and the leaf may remain green for two years or longer, but no new plant will develop. The first and most logical step towards control i of .these diseases is to ensure that the rooting medium is sterile. This can be accomplished by electrical or steam sterilization, or by,drenching the medium with a-saturated solution of potassium permanganate or some other good fungicide, provided that no toxic residue is left by/ i t . • More recently, considerable attention has been given to the- technique of dipping the cuttingssiri fungicidal solutions, Fermate, Zerlate,. Phygon, Copper A, ete., the theory being that immersion of the cuttings-' in such a solution would eliminate the chance that disease could be introduced"into the cutting bed on the cuttings themselves. .It was also: believed, by some workers, that the residue on the cuttings would bee sufficient to/prevent the entry of any,disease organisms that may happens to be in the rooting medium^from-gaining entry into the cuttings. At first, i t ,was feared that such treatment .would have an inhibiting effect on the initiation and development of roots> but some workers have found-that theopposite is true, ; and that some of these fungicidal dips act; as effective root-inducing substances; (This aspect is dealt with more fully under III, "Chemical Means of Stimulating Root-Initiation). V/hereas-Hyatt ( l j ) , found Copper A, when used! as a pre-insertiom dip, markedly reduced loss from disease with Camellia cuttings, Swanson (24), using the same treatments, found no significant reduction. .It seems likely/that such dipswould have l i t t l e or no effect unless the medium was free from contamination}! that is, .thecdip may possibly have an effect im controlling: disease;carried on the cuttings themselves, but beyond that, not too much could reasonably be expectedi• - 155- -Some very recent publicationasClJf2j) indioateethat satisfactory control of cutting-bed diseases can be obtained byy sprinkling the medium with Spergon:solutione( 1/5 oz. per American gallon^of water), applied; with a watering can. Should the disease become evident at a later date* in spite of this precaution, ,this solution eayiibe safely applied over-the: cuttings*: and can be expected to give satisfactory control. .This simple-precautionary or control measure should obviate the necessity of further tests-to determine the actual value of fungicidal dips, applied solely/ for the purpose of controlling damping-off, although these treatments might s t i l l prove to be worth whiletto stimulate root-initiation-. III. CHEMICAL MEANS OF INDUCING OR HASTENING ROOT-INITIATION. 1. Application-of Hormones: For the-past fifteen years, horticulturalistsi both amateur and; professional, have been decidedly "hormone-conscious". The discoveries of Zimerman, Hitchcock, Wilcoxon, Cooper, Stoutemeyer, Skinner and many others, have resulted in the compilation of a vast source of data pertain-ing to the occurrence, nature, properties, activities and uses of thee chemical growth activators variously known as plant hormones, phyto-hormones, auxins, growth substances and growth regulators* One field;ini which .a great deal of work has been done has been in the use of these: substances to stimulate root-initiation on cuttings of hard-to-rootcspecies. Although many substances have been tested: for use in this regard* at present only a few are accepted as being sufficiently safe and reliable to warrant their being placed: on the market. Various methods of applying these substances, too, have received a great deal of attention. (15> 10; 21; 5; 25; 29; 11). - 1 4 -To give anything resembling an adequate summary of the work done to date with these plant hormones ris quite beyond the scope of this work, and is rendered quite unnecessary by the recent publication!of an excell-ent aocount by Avery and his associates, ( l ) . Suffice i t to say that this work is s t i l l continuing, and that there; is every reason to believe that the result will be the introduction of hormone preparations which will be far superior to any commercial prepar-ations that are now available. .Of those now on the market, most contaim indolebutyric acid, (the most effective and^afest growth substance for the widest range of plant material),(15 pg» 587), naphthaleneacetamide, naphthalene acetic.acid, or mixtures of these combined with commercial talc* According to Hyatt (15)1 a l l of the hormone powders;available on; the market under various trade names, (such as Rootone, Hormodin, Stim-Root, Quick-Root etc.), have been found to hasten.root development om Camellia japonica* The work of Hitchcock and Zimmerman (12), Stoutemeyer (22), and others? indicates that there may soon be further developments of these hormone preparations which will be s t i l l more effecive. 2. .Use of Fungicidal Dips'. Very recently, workers using fungicidal dips in an endeavor, to reduce loss of cuttings through the action of fungus diseases? have; found that theseetreatments? in some cases? have a marked stimulating^ effect of root initiation. Hyatt (13), working with;Camellias, found this; to be true of CopperA, and to a lesser extent,.with Fermate and Spergon. Swanson (24) found Phygon alone, and Fermate? Copper A, and Zerlate? used in combination with! Hormodin #2, produced a significant increase-in the rate:of rooting of Camellias over that produced by Hormodin alone,. - 15 -although the effect of such dips on the control of fungus diseases was disappointing. Combinations of Fermate plus Indolebutyric acid gave as significant increase in rooting, and decrease, in lossr.from rotting, with. Geraniums, in the work of Whitee(28). Newtoneand Lines;;(l7) found Fermate and Spergon to reduceeloss from rotting, and to encourage rooting,,withe Allumi Cypress* However, as yet there seems to be some disagreement as to just how effective such treatments are in stimulating root-initiation* and just how efficient they are in controlling the fungus diseases? im question, as they were originally intended to db. Further work is warranted. OBJECTS OF THE EXPERIMENTS. From the foregoing, i t appears that there is a wide scope on which to base.further experimental work.. Although: some work has been done to determine the value of vermiculite combinations as: rooting media* evidences in the references'encountered: seemsto be lacking in conviction.. There is a strong possibility that: combinations of peat, ,sand and vermiculite may prove.definitely^superior tODvermiculite used alone,;or to sand-peat combinations so generally/ used. • The>evidence reviewed:indicates that, with- Camellias,, work has: been confined to the use of only two typesr:of cuttings* the- ordinary stemi cutting, and the leaf-bud cutting..The former, place rather heavy demands: on the stock plants from which the cuttings are obtained-, while the latter involve their ownipeculiar difficulties. Several other types of cuttings could be devised, for example, partial stem cuttings from apical, basal, or intermediate sections of the current year's wood* and consisting of. single or multiple bud nodes. It is not impossible that, through the use of on or more of even these few types, the difficulties or disadvantages: encountered in the use of stem or leaf-bud cuttings, may bet partly, or: entirely overcome. Findings relative to the use:of fungicidal dips to reduce loss-of cuttings through the action of Rhizoctonia, and to promote rooting, have not, as yet, become conclusive. Although..the? use of fungicides may never supplant, the use of growth-subBtances to promote or hasten root-initiation, - 17 -there remains the possibility,that, used in combination with hormones,, they may enhance their value by increasing their effectivenessFurther evidence is necessary, too, beforeta decision can be reahed as to whether or not the fungicidal dips are effective in controlling cuttingrbedi diseases. It was with these objects in mind that the following experimental work was conducted* - 18 -EXPERIMENT I. COMPARISON OF RESPONSE OF LEAF-BUD A N D STEM CUTTINGS  TO TREATMENT WITH.ROOTONE. Materials and Methodst On September 28, 194-9 , the following cuttings of. Camellia-japonica* var. Donckelari, were prepared,,treated: as indicated* and; inserted! im a medium consisting of 2 parts sand and 1 part peat,,in a closedi frame im the University, greenhouse. The frame was equipped!withethermostatically/ controlled soil cable for supplying bottom heat, and was covered with glass* which in turn, was whitewashed for shading.. 1 ) .Twenty ordinary stem cuttings of current season's-growth, with: lower leaf pulled off to facilitate insertion'.into the medium* dipped:iniRootone (containing, active hormones as Naphthyl Acetamide, imtalc. carrier). . 2) .Twenty ordinary stem cuttings as above, no treatment. 5).Twenty leaf-bud cuttings of similar growth of the current season* dipped in Rootone. A).Twenty leaf-bud cuttings, no treatment. All cuttings were watered well, overhead* immediately after insertion, and at weekly/intervals thereafter. No bottom heat was supplied at this time. OmiOctober 28, 194-9* removal of a few cuttings from reach treatment revealed no apparent change. The; thermostat was set to maintain bottom-heat of 7 5 degrees F. On November 28, 1 9 ^ 9 * a l l cuttings were examined and results recorded. -19 -Results and Observations: "Response of Leaf-Bud and Stem Puttings to Treatment with^RootJone", No. , TYPE OP PUTTINGS , TREATMENT ROOTED CALLUSSED DEAD 20 stem cuttings Rootone 18 * 0 2 20 stem-cuttings None 16 ..** 2 2 20 leaf-bud cuttings Root one- \Q *** 0 2 20 leaf-bud cuttings - None 2o #*** 0 0 * Rootspvery long.:(4 to 6"), three to five in number, with:sideeroots up to 1/2" long. Root very brittle, and most difficult toohandle. (see pg.20). ** Roots inrthis treatment were; much ;;shorter than those on icuttingsa t r eat edd with Rootone? (2 to 5? I°ng)» less brittle?.and well-branched; with numerous side-rootlets. These cuttings, consequently, were?;much; easier to handle thanithose which had been treated-. *** Roots on these.treated cuttings werecvery long, and'quite.well! branched? but again, were very brittle? fleshy, and difficult ;to handle: without breaking. Twelve;of the 18 cuttings in this treatment whichhhadi rooted'showedopronounced blackening of the axillary bud; closer examinat-ion reveaed that theseobuds were deacV. .The buds on the remainder appeared the same as they were when the cuttings were taken. **** The roots;on these cuttings Keresonly/about half as long/as thosee on the treated' cuttings of the same' type^ .but were stoutefc-? branched; more; profusely, and muchiieasier to handle. Theebuds omthree of the .-twenty/ rooted were black, but the remainder werecsprouting strongly.. - 20 -SKETCHES TO ILLUSTRATE THE DIFFERENCES IN RESPONSE BETWEEN STEM AND LEAF-BUD CUTTINGS, TO TREATMENT WITH ROOTONE. Treated-with Root one*: No treatment. - 21 -Discussion* With both eto and leaf-bud cuttings, ,rooting was quite-satisfactory/ by the ends of two months, without the use of a^  root-inducing hormone.-In the case of the leaf-bud cuttings,,a higher percentage of rooting was obtained on the checks-than on those receiving the Rootone*. With ibothlitypes-of cuttings, ,a more compact and much;more durable-root system was obtained omthose cuttings receiving no hormone treatment.. The roots on;the treated cuttings were admittedly more extensive.;than those on the cuttings receiving no treatment, but this extensiveness, coupled with the fact that the roots-were extremely.fleshy and brittle* made removal of the cuttings from the medium, and separation another, most difficult, and resulted) in-many cases, in the breaking of several of the largest roots.-Of course, there is the possibility that those cuttings which had:received the-hormone treatment a? more advanced stage of rooting, at the time of examination,: and that, , although there was no sign of rooting or callus formationeat the time of the first examination, (Oct. 28), the treated cuttings may haveebeem satifiactorily rooted at a considerably earlier date between the time of the first and second examinations. If such were the case, removal of the: treated cuttings at an earlier date would facilitate the handling. The actual differencesrin the types of root-eystems formed aree factors of considerable importance..Theeroots on the treated cuttings were branched only near the apex ; removal of these cuttings from the; medium at an earlier date would entail moving them before these:side roots had formed. -Also, the roots on the treated cuttings were very fleshy, and brittle; the time of removal from the medium would have l i t t l e effect on this disadvatage. On the other hand,.the roots on the untreated! - 22 -cuttings, -being more:.compact and more profusely branched near the base, weremore;easily removed from the medium and separated from one another without damage* Because these roots were much less succulent and fleshy than were those on the treated cuttings, there was less tendancy for breakage to occur. Thus i t would seem that, even though a week or so longer would be required for adequate rooting to take place in some instances, for some Camellia varieties at least, more satisfactory root systems would be obtained without the use of root-inducing hormones. This does not imply that, for the notoriously diffiult-to-root varieties, use of the hormones-might not be worth while, for in such,cases i t is not unlikely that the advantages of faster and a higher percentage: of rooting would moee than offset the disadvantages in-;the typee of root system that might result. With the leaf-bud cuttings, a serious'disadvantageewas evident ,ihi the treated cuttings in that of those;cuttihgeewell rooted, ,12/18 or. 67% wereeuseless because the buds were blackened and obviously/dead.. Thus?. of the 20 leaf-bud cuttings taken;and treated! with Rootone, only six?. or 50%, had a chance of ultimately forming plants, whereas of the twenty that had received no treatment, seventeen, or 8?%t at the:;time they were; removed from the medium,/were strong, healthy, and had vigorous buds? already shooting into vegetative growth. Just how the hormone powder adversely affects the.buds on the leaf-bud 6 cuttingsrcannot beestated definitely. If i t were direct killing of the tissue-^ caused by too strong a concentration off the hormone, i t does; not seem likely/that the cambium and other tissues exposed by/the; cut made-in the .preparation:!of the cutting, ;would have suvived undamaged:. It seems--even less likely/that the cuttings would-have formeddroots.-There is a-possibility that the killing may have been indirectly/caused! - 25 -by-the hormone, in-some way,,making the tissues more susceptible to the attacks of'Rhizoctonia* which disease supposedly caused" the death of the buds on V0> of the untreated cuttings*. The fact that &jfo of the untreated leaf-bud cuttings bore buds that were healthy, and actually sprouting into vegetative growth* should:1 be emphasized. It is mostimportant that the buds should be stimulated into growth as soon as possible, mainly to reduce the chances-of ultimate, infectiomby/Rhizoctonia. The actiom of the root-inducing hormone,, aside from modifyng the type of roots formed", and causing death of a-great number of the buds,, apparently had a retarding effect on the vegetative conditin of the.buds that were not injured!. This in itself, could be considered reason enough to advocate: against the use of such substances on this particular type of cutting. In some cases, the entire cutting was dead. This occurred with 10$ of the stem cuttings: in both treated'and'untreated groups, and to 10$ of the treated leaf-bud cuttings. Indications are that Rhizoctonia was responsible, since the cuttings exhibited the usual symptoms, blackening from the base upwards. In the case of the leaf-bud cuttings, there:is the possibility that the hormone treatment was influential, since none of those untreated'was affected. The dead leafr-bud cuttings did not show the scorching that is generally indicative of toxic concentrations of hormones; on the contrary, .the symptoms were typically those of. fungus infection-. This may be accepted as further evidence that applications of Rootbne to leaf-bud cuttings of Camellia, may tend to increase: their susceptibility to attack by Rhizoctonia. Consideration-!must be given to the possibility that the detrimental effect ofthe hormone treatment on the leaf-bud cuttings:may be due to the amount applied in proportion:to the amount of tissue involved in the: - 24 -cutting, approaching, i f not attaining, the lethal dose. .When the hormone;, is applied in the powder form, the amount in i proportion ito the size of; the cutting, which, adheres to a leaf-bud cutting, compared withe that which adheres to a larger stem cutting,-}is very great indeed'.. The safest way of surmounting such a difficulty would be to use aweaker hormone: preparatiomfor the smaller cuttings* To apply smaller amounts-of thee regular strength preparation)would be undefendable, and would require: too much caution and time inethe application* With those varietiesewhich root as readily as does Donckelari, the most satisfactory recommendation would be to dispense with the hormone treatment* Conclusions* The results-obtained: in this experiment, indicate that, at least, with Camellias"Donckelari", stemecuttingsroot moreesatisfactorily/ whem applications of Rootone are not made..The somewhat lower rooting percent-age obtained with untreated cuttings, is more than compensated, for by the:, superior type/of robtjsystem which is developed*.Thisedoes-not necessarily mean that with some varietiesewhich are perhapseslower or mores difficult to root, ,better or significantly faster rooting may not result from-its: use, orttheeuse of other root-dnducing substances*. The results iridic ate epos i t ively,, that Rootone is deleterious whem applied to leaf-bud cuttings of this variety. In this experiment,,such applications resulted; inna very high loss,.due mainly to death of the axillary buds. Exactly how or why this takes place was not determined* but the evidence .suggests that weaker hormone preparations should be used on leaf-bud cuttings of Camellia* i f the variety is sufficiently - 25 -slow or difficult to root, to warrant their use at a l l . . This«experiment-, suggests that, with varieties-which will root as easily as Donckelari does, .better results would probably/be obtained .with: ;untreated: cuttings.. EXPERIMENT: II. TO DETERMINE THE VALUE OF VERMIOULITE IN ROOTING MEDIA  FOR THE PROPAGATION OF CAMELLIA CUTTINGS. Materials?and Methods* OnrSeptember 28,19^9> twentyrfive cuttingssof an old, nameless variety of Camellia japonica? with very small, .semi-double red flowers:, were taken of current season's growth in the usual manner for.stem cuttings, and inserted without further treatment innflats, in a medium:consisting of 2 parts sand, 1 part Terra-Lite, and 1 part peat. Terra-Lite:is a commerce i a l name for a fine, uniform, grade of expanded vermioulite, specifically designed for horticultural use,. At the same time, twenty-five similar cuttings .-were inserted im Terra-Lite alone, and a-further twenty^five were inserted in the medium: generally employed, consisting of 2parts sand'and 1 part peat. The media were not compacted, beyond that .each cutting was gently firmed iny hold i t upright,.This was done with very gentle press-ure, insufficient to compact the media. Then a l l the cuttings were watered overhead, and placed in a glass-coveredi greenhouse propagating frame;: as in Experiment I. On October 28, 194-9, the thermostat was set to maintain bottom-heat of 75 degrees F. On November 28, 19^ 9, the cuttings were lifted and examined, and the results were recorded.. - 27 -Results and Observational Table-to show Effect of Various Media-^ on Rooting Response of Camellias. MEDIUM CUTTINGS ROOTED CUTTINGS CALLUSSED CUTTINGS DEAD TOT-AL Sand-peat- TerraMte:2:l:l 22* J 0 25 T erra^Lit e - al one 12 ** $ 4 25 Sand-Peat 2:1. 10 *** 8.-- 7 25 * There .was no..sign of disease on the cuttings-in this medium* Water supplied at weekly intervals was'adequate-to keep the medium uniformly moist. .Theerooting. percentage was very satisfactory, and the roots were: durable and compact; (Seeeillustration, page §9).. ** Although};four cuttings were dead in this medium, death seemed to be a result of drying rather than of diseases.The medium wasnmoist at al l times, but i t was noticed that i t was apparently not heavy enough, to hold the cuttings securely.upright. Particularly at time of watering,, the cuttings shifted 1 position, and probably air-spaces developed." at the base of some cuttings, causing them to dry out. .Those that rootedi formed long, fleshy roots which were: sparse ( two, three or four in no.), and branched"but slightly near the apex* (See illustration, page 29)* *** The dead cuttings i n this medium showed evidence of Rhizoctonia?. infection; the stems had turned black at the base, and this blackness was progressing upwards, in many cases having reached or-passed the^ surface of the medium by the time of examination*. In some casees the: leaves had dropped off before: examination, and in the remaining cases.: - 28 -whereothe cuttings were infected, the leaves dropped-off at the slightest touch* Those that had* rooted seemed quite healthy, but the roots, .though; more compact and numerous than those in the Terra-Lite alone, were;less numerous and less well branched, than were those in the sand- Terra-Lite-peat medium* (See illustration, page 29).. Discussion* This experiment was considered'worth-while,,because no previous-worker, as far as could be ascertained,.has conducted a satisfactory test to compare sand-vermiculaite-peat with sand-peat mixtures'.. (see pg 10) The most satisfactory results were obtained with the> sand-vermiculite-peat mixture,.which proved definitely superior to Terra-Lite used" alone.. The Terra-Lite, in turn,.proved slightly better.than the sand-peat combin-ation,; reetotal rooting and prevalence of disease. This is in agreement, with the results obtained by Sawada (27). The sketches on page 29 adequately illustrate the differences: im types of rootcsystems formed in the three mediarused;in the experiment. At first glance, i t would seem-that the largest and most satisfactory-root system1 was formed in the Terra-Lite medium-. However, due consider-ation must be given to the fact that these roots-were extremely brittle, and fleshy, and, being long, were intertwined: with the roots of adjacent cuttings. As a result, the difficultiesrencountered in removing the cut-tings from the medium, for potting up, without causing considerable: damage to the roots, were sufficiently great inthemselves to justify the conclusion that roots formed in the Terrar-Lite medium were not of a-- 29 -SKETCHES TO ILLUSTRATE TYPES OF ROOT FORMATION EVIDENCED IN VARIOUS ROOTING MEDIA. Sand - Terra^Lite - Peat. Rooting 88% Roots very durable, and easily handled without breaking. Terra-Lite »-Rooting 40% Roots f a i r l y durable, but not as easy to handle as those i n sands-Terra-Lite-peat mixture. ( a l l XI). type nor durability to be.practical. On the other hand, the roots formed-, in the sand-Terra-Lite-peat ; medium were veryydurable? and well branched to form:-.a good,, well branched root system. These:cuttings were easily removed from the medium, and separated from one another, without suffering appreciable damage.. Thus, the conclusion that the sand-Terra-Lite-peat mediumis superior, to the other combinations used, seems to be justified by the evidences of a higher:rooting percentage* reduction/of loss from disease and drying out, and the development of a much more, durable and compact root system. The superiority of the sand-Terra^Lite-peat ..combination over the; Terra-Lite alone is probably due to greater firmnessj which holds the. cuttings more securely, and also to the presence of peat which gives-the. acid ;reaction so desifable/for Camellia-cuttings.. Its superiority over the sand^peat medium-is^presumablyvdue to the attainment of more,nearly ideal air and moisture/conditions within the medium. Conclusions t The rooting medium consisting of twooparts sand, one part Terra-Lite, and one part peat (by volume), proved definitely superior to media conr-sisting of sand and peat, or Terra-Lite alone, for the propagation).of these Camellia cuttings.. This superiority was evidenced by a higher rooting percentage? sturdier, more compact but vigorous root systems, and reduced loss/from disease and drying out*. - 51 -EXPERIMENT III. RESPONSE OF VARIOUS TYPES OF CUTTINGS  TO TREATMENTS WITH ROOTONE AND FUNGICIDAL DIPS, IN£THE  PROPAGATION OF CAMELLIA "DONCKELARI". Materials and Methods*-On November 15, , 1949» threectypes of cuttings,; as-described below-, were prepared from:well-ripened shootsrof current season's growth, of. Camelliarjaponicaj var. "Donckelari"..Sixty cuttings of each;type weres made. Typeel cutting* - consisting of the basal portioniofi thee current:, season! s shoot,, .from thee junction of the previous season! s growthi up to and including the first leaf and axillary bud. These.cuttings averagednabout 2 l/2 inches long.. Type II cutting* - consisting of theeapical bud, one axillary bud;. below i t and the leaf subtending i t , and the stem down to thee next bud, aboveewhich the cut was made. Flower buds were apparent om most of these:cuttings. The average length of the cuttings of this: type wasabou 1 l/2 inches. . Typeelll cutting* - was reallyy a modified;: leaf^-bud cutting, only/ instead of a shield of bark being cut off the main stem, to carry the bud and subtending leaf, the stem was cut :directly across, 1/4" below theeleaf and bud. The stem above the bud was cut cleanly off as close as possible to the bud without damaging i t , with a-sloping cut directed downwards and away from the bud. The sixty of each of the three types of cuttings were divided!into - 52 -six-lota of ten each, allowing for the following treatments: 1. Check - no treatment* 2. Immersion of entires cutting in Perenox; solution;-!(1/2 teaspoon per quart: of water), for about ten seconds.. 5» Perenox:dip, as in 2, followed by dipping the basal portiom of the cutting in Rootone. 4. Immersion in itap water, followed by dipping/basal portiom in Rootone. 5..Immersion of entire cutting in Copper A solution; (1/2 tsp. Copper A per quart of water), ,for about ten seconds.. 6.-Copper A dip, followed by dipping basal portion of thee cutting imRootone.. After treatment, the cuttingsrwere:inserted;firmly in as medium com-sisting of 2 parts sand, 1 part Terra-Lite, and 1 part peat, (by volume?), in flats,.following which they were syringed .lightly to settle.the medium. The flats' wereeplaced in an outdoor cold-frame* covered", with; a-Cello-Glass sash,; and shaded, with double thickness of cheesecloth* Water waB applied by .overhead sprinkling, at weekly intervals; hereafter.. On December 1, lp49» the flatsewere transferred to an indoor hot-rbed, or propagating frame, supplied with bottom heat of approximately 70 degrees Fahrenheit.. Examination of a few cuttings from each block at this time, revealed no appreciable changes. On January 15> 1950» the cuttings in a l l tests;were examined, and the results.of the experiment were recorded.. *55* Results; and Observationst Table to Show Response of Different Types of Cuttings to Treatment,, With Rootone and Fungicidal Dips.. TREATMENT TYPE I cutting s TYPE II cuttings ** TYPE III cuttings *** Total Rooted; None-6 callus sedi 2 not cal. 2 dead" 2 rooted 4 callussed 4 dead 4 well rooted:. 6 callussed # 6/50 Perenox dip 4 callussed-6 dead 4 rooted : 2 callussed 4 dead 6 well rooted 4 callussed-# 10/50 Rootone. Perenox: dip. 2 callussed 6 not cal. 2 dead 6 rooted 4 callussed 10 very well rooted # I6/50 Rootone: 2 callussedi 4 not cal. 4 dead:. 2 rootedc 4 callussed 4 dead:. 4 welllrootedi 6 callussed 6/50 Rootone. Copper A dip. 8 callussedr! 2 dead 10 callussed 2 well rooted 8 callus sed- 2/50 Copper A dip. 4 callussed 6 dead 2 rooted:. 6 callussed 2 dead 4 callussed 6 dead 2/50 Total Rooted Each Type. • 0/60 16/60 26/60 (in a l l cases? i f rooting^ was too weak to be of practical value, the; cutting response was classed as;;"callussed"). * With a l l Type I cuttings,; rooting was unsatisfactory, regardless of treatment. Twenty percent (2/10) cuttings:in the check plot:and in the Copper A dip plot rooted, but so sparsely that they were classed as cal-lussed, because? ,,onia-practical basis, such cuttings would have to be - $k -returned to the medium for further root development, or discarded;, Ini a l l cases, those cuttings of this type:that were callussed-, were bearing quite well developed flower the axils of the leaves, in addition: to the vegetative or shoot increase in size had occurred; withi the latter. There was no sigmof flower buds eon the wood; in the regiom from which these cuttings were made,.at the time when the cuttings were^  taken..Most of these cuttings which were classed as callussed in ithe tabulation of their response, were not callussed in the sameway as were those invthe Type II and III blocks; the callus with the type I cuttings-was comparatively.slight, and restricted to a ring of callus tissue;in: the approximate region of the cambium layer, but the entire basal region of these cuttings was somewhat swollen. ** With the Type II cuttings,, rooting, where: i t did octcur, was fairly strong. Inmearly every case, the rooted cuttings;carried:veryywell devel-oped flower buds, which, however, had been present, though not so large, at the time when the cuttings were taken. In many cases these buds dropped off at a touch of the finger, and "where, in a few cases, this did not Occur,,the leaves f e l l off instead. *** With a l l Type: III cuttings, ..rooting, .where i t did take place,. was very strong. This was particularly noticeable on those cuttings which had: received the RootoneePerenoxxtreatment. Although sixxcuttings were: completely dead in the Oopper A treatment, i t was noticed particularly that in not one case- was there evidence, of a dead axillary bud while the; remainder of the cutting seemedo healthy. # indicates :=buds - sprouting well.. Sketches-appear on page J5> whi'chn illustrate the differences: in> response which resulted:from the Perenox-Rootone treatment. - 55 -SKETCHES TO ILLUSTRATE THE THREE TYPES OP CUTTINGS USED, AND THEIR TYPICAL RESPONSE TV/O MONTHS AFTER TREATMENT WITH ROOTONE AND PERENOX. Nov. 15, ,19^ 9. Flower bud Typeel. Slight swelling Flower bud TypeelI. Type-Ill. ( a l l Xl/2), Jan* 15, 1950. - 56 -Discussion: Rather consistent differences = were noted'to occur between-the/; responses; of the three types of cuttings'. The results.ihdicate= that Type. I cuttings would! probabiy-mever be satisfactory. The reason for this may be linked with the absence of the apical bud and its possible .hormoneo relationships - but if; such were the case, the-: Type ell cuttings would be.-expected to far the beat results of the threertypes used, (whichi they did not do), and Type III could hardly be expected to give better results than: those evidenced by/Type:I.-Because Type III exceeded Type; II ihomost cases? ,and'far exceeded! Type^I, it .seems;more.likely/that the. ratio of leaf surf ace. to stem may be the import ant influencing factor.. Of course, the basal portion-of the current!.growth, being the first to; ripen? may have a-different carbohydrate/nitrogen ratio,, or may contain) larger amounts or different types of carbohydrates. This ;ih turn, could! have a bearing on the. hormone constituents in the region, and in turn,; could be taken to account for the/unwonted;! flower-bud' formation*. It would! bee interesting to note just .what would be the comparative response of these cuttings, i f they were taken at an earlier date, before the woodi was so well ripened. The absence-of damage to the buds by -Rhizoctonia or by the chemical treatments involved, in cuttings of Type III, encourages the hope that possibly by use of these cuttings instead! of! the usual leaf-bud cuttings,; the difficulties so often encountered with the latter could be largely overcome. Certainly, there is less chance of mechanical injury to the buds; in the preparation of Type III cuttings* Conclusive data-on the compar-ative responses of the two types can only be: obtained as a result of more: extensive tests* If the indications of this experiment were borne out,.. -57 -there iB a possibility that Type III cuttings: would replace the leaf-bud: cuttings used; in .present techniques. . The Type.H cuttings responded: well enough to warrant further study, particularly of the nature of ascomparison!of their performanceowith that of stem cuttings as:generally,recognized..Possible modifications of. the Typeell cuttings of this:experiment,;to include at least one more;, leaf and axillary bud would probably facilitate handling,, and would mean: that the rooted plant would: more: nearly approach the size of that obtained from the regular stem cutting..If further experimental work verified the: results obtained in this test,,the logical conclusion!would be that better resultswouldcbe obtained from Camellia stem cuttings:, i f i the-..basal i. port-ion of the current .season'is-.growth were not included as a part of the cutting. .Certainly,' the response of the Type :I cuttings* .in this experim-ent, indicate that this basal regioniis* in itself, slow to root; just: whether or not this tendancy is largely overcome by the presence:of the: apical region of the shoot,; cannot be stated: at .this time.. Although!ithe results of the individual chemical treatments were not as consistent as might have been hoped for,,the evidence is sufficient to indicate that Rootone alone did not increase the rooting percentage.:over that of the checks. The roots omthose cuttings which received the Rootone; wereesomewhat stronger at the time of examination, but in! a l l probability*; i f the cuttings had been given a longer rooting period*,the same: difficultr-ies re fleshiness, brittleness* and lack of compactnesscthat were: evident as a result of Rootone treatment in Experiment , 1 , would have become: evident. The figures-denoting the total .number of cuttings rooted in:each:treatment, (including ten cuttings of each of the three types;), indicate that thee Perenox: dip in Itself gave* somewhat better:results than did the:Rootone. - 38 -However, the ccombination!of Rootone and the Perenoxxdip gave /.markedly better results than did any other treatment, with both Type II and Types III cuttings.--This superiority was evidenceddby markedly faster rooting, greater uniformity, and at the time of examination, the root systems, especially on the Type III cuttings, were ideal for transplanting or potting.. The Copper A treatment alone, gave most unsatisfactory results* Wheni combined with Rootone, however, this treatment, though!not as effective as the Rootone-Perenox combination,; could be considered-superior to both the check :and the Rootone treatment, .for none , of the cuttings wereedead. On the contrary, a l l were^at least well callussed. The treatments also had various effects ;ori the shooting of the-, a x i l l -ary buds-of the Type III cuttings* As was the case with the-buds on the leaf-bud cuttings in Experiment I, the Rootone alone seemed: to have an inhibiting effect on/the growth and development, whereas in most.cases;* the buds on the checks were greatly/enlarged, and showing evidence of. vegetative growth. .It is noteiforthy that the use of the Perenox; dip in addition to the Rootone, apparently overcame this-difficulty, and is further evidence to support the superiority of the Rootone-Perenox:treat-ment over the others.. Consideration should be given to the fact that a great majority/of the cuttings which, at the time of examination,,had callussed;only,. would-probably have formed-roots,.possibly within a period-of another two or three weeks* If allowance were/made for this-eventuality,,there/is the/possibilityythat 100$ rooting/would take place in!all:cases-with the Type: III cuttings,, except those/which had Ureen treated with the Copper A alone. Similarly, greatly improved:rooting percentages/would be expected: with the Typed! cuttings* The over-all picture re the comparison! of the. - 59 -effectiveness of the various treatments would remain unchanged! insofar as. the Rootone-Perenox treatment would s t i l l be unchallenged*.However, the possibility arises? that the; Root onerrOopper A treatment would them give better, though slower, results than either the check or the Rootone/ treatmentsi By this time, root development- on the Rootone-Perenox< treat-ment : would be sufficiently advanced to enable/it to maintain.) its super-iority over the other treatments, and in al l probability, the axillary< buds-on the Type III cuttings in this treatment would/have sprouted into strong vegetative growth.. - 40 -Conclusions* The. response of the Type .1 cuttings, consisting of the basal portion; of the current .season's growth up to and including the first leaf and its-axillary bud/ was unsatisfactory regardless of treatment. .This might be: taken to indicate that the physiological condition .of the wood in the region of the junction.:of the growth of the current and previous year tends to have an inhibiting effect on rooting. Further work in this; regard may indicate the advisability of restricting: stem cuttings-to the upper portionaof the growth of the current season, at least i f the cuttings; are taken as late asoOctober or November in this region.. The response of the Type II cuttings, consisting of the apical bud, the uppermost leaf (or leaves? i f the internodal spaces near the apexx happened to be very short), and the stem down to but not including the. next bud, was sufficiently satisfactory to indicate that such cuttings could be of practical value. Theseccuttings would be much less demanding on the stock plant than are the usual stem cuttings.. The modified; leaf-bud cuttings? Type. I l l , inwhich the entire stem • portionireplaced the shield commonly taken in the preparation of usual leaf-bud cuttings? showed-encouraging evidence of being less susceptible, to loss-of the axillary buds through the action of Rhizoctonia. Further work may indicate that ..the performance of these cuttings is - sufficientlyr superior to warrant their adoption-instead! of the leaf-bud cuttings; at present sometimes used.. The. foremost conclusion;in regard tooths various;: chemical treatments used .is that the Rootone-Perenox:;treatment :was most satisfactory? with; bothiType II and Type III cuttings.. The Perenox; dip alone gave better results than either Rootone alone? - 41 -or no treatment.. The Rootoner-Copper A treatment seemed-tooretard rooting, but givem more time, might ultimately have resulted in-better? though.slower, results? than was evidenced by the use of Rootone alone, or no?treatment* The Roottone-r'Perenox:treatment :,wae superior to a l l other treatments? in a l l respects* It resulted in ahigher rooting percentage, fasterrandl better root formation? and earlier: shooting of the axillary buds on Type; III cuttings? than did any of the other treatments/employed. Whereas:- the; use of Rootone alone seemed to oinhibit the shooting of the; buds con these; cuttings,,the useL of; Perenox: as a dip prior to treatment withhthe Rootone apparently offset ;thisoihhibiting effect of the hormone*. -42 -SUMMARY. The work ih'connection with this Thesis was undertaken to devise ways of improving the technique of propagating Camellias-from cuttings* The? inclusion-of a^ -review of literature: pertaining to those fact or B~ which) influence the rooting of cuttingsj. was intended primarily/ to focus the; experimental work onto specific aspects of the problem* In the first experiment, a comparison;was made between the response, of leaf-bud cuttings and stem cuttings-of Camellia: "Donckelari", to treatment with Rootone, .(a commerciallplant hormonB. powder: containing naphthyl acetamide .as the growth, substance). The results indicate:that the; superior root .system developed: by the. untreated stem cuttings?(evidenced-by more durable and more-compact roots),, more than offsets the advantage of a 8lightly/higher rooting percentages obtained through the application of Rootone* This .was not taken to ;mean;that better or significantly faster rooting may not develop as a result of the use of.root-inducing substances on cuttings of varieties which are.much.slower or more.difficult to root, than is the variety used in this-experiment. The use of Rootone omleaf-bud cuttings of this same variety resulted"in:severe: loss through the death :of the axillary buds* The evidence suggests that better results could be expected i f no hormone applications were made on: leaf-bud: cuttings-, of varieties^as easily rootednas is "Donckelari", and that, with:more difficult subjects? a-leae concentrated: hormone application, would probably be advisable. A second experiment was conducted to determine the value of Terras-Lite, ^horticultural Igrade of vermioulite), in rooting media for thes propagation of Camellia cuttings. The results indicate that a mixture of 2 parts sand, ,1 part vTerra^Lite, and •'lip art peat (by/volume) i s superior to the medium*generally used, and consisting of sand and peat., only. This superiority was evidenced by a higher rooting percentage, sturdier, more compact and vigorous roots* and reduced" loss-from •disease-; and drying out.. The third .experiment was designed to determine the response of three:, distinct- types of cuttings to treatments withe Rootone, and Perenox-and Copper A pre-insertiomdips alone and in combination with the .Rootone. The results'indicate: that the first type/of cutting, (which consisted! of the basal portiom of the stem of thee ripened growth of the. current:, season-together with; the first leaf and its axillary .bud), was definitely prer-disposed against rooting..The second-type:of cutting, (consisting of the; apical bud, first leaf and axillary/bud* and the stem portionedowmtoe but not including the second leaf and bud, a l l of the new shoot), and; the third type, (eachi.of which .consisted of one leaf and axillary bud taken• from a position ofi the new shoot intermediateebetweemthe basal and: apical Heaves* and including the entire stem in the: immediate proximity of theebud), rooted well enough /to be of practical value..The former rooted..'at least as easily/as do ordinary stem cuttings* and are much less-demanding on the stock plant; the latter have the advantages: of leaf-bud! cuttings in that they are economicallwherevcutting material is very limited* and, according to the/results of this experiment,, have the' added' advantage of being much less susceptible to die-back of the all-important; axillary bud* With both types:of cuttings* Rootone alone/gave no increase: in,rooting over no treatment, and with the.modified-leaf-bud or Type III cuttings*-,seemed!to have a"marked!inhibiting effect on the: sprouting of the axillary bud. The combination: of the::Perenoxxdip and Rootone applicr atiomgave. re suit SF> that were (markedly superior to those/of any other treatment, re/percentage:rooting, and faster and better rooting..In additions the Type/Ill cuttings given this?treatment ?evideneed:!no inhibit ion-of the axillary bud-; Thus i t appears-that the-Perenoxxhad the effect of overcoming the inhibiting effect of! the Rootone? om development of? the bud, and ultimately, of the new shoot..The Copper A treatment, - alone* gave unsatisfactory, re suits j but in combination with: Rootone, indicated! that i t might give better, though slower rooting response* thanxdidl Rootone itself. . - 4 5 -REFERENCES CITED. Number: 1. AVERY, GEORGE S. Jr., et al - 1947 - "Hormones^-and-Horticulture^'. McGraw-Hill'Book:Co. Inc..New York. 2i COCHRAN, GEORGE W. - 1945 - "Propagation of Peaches^ from Softwood-Cuttings". Proc..Am. Soc..Hort. Scii, vol 46 : 230. 3i. COOPER, W.C. - 1944 - "The Contsentrated-solution-dip Method^  of' Treating Cuttings^With"!Growth Substances^'. P r o c Am-. Soc. Hort. Sci., vol. 44! : 535. 4 . . COPE, J.L. - 1947 - "Vermiculite; as a Medium for Propagationi by Cuttage". AmeriCamellia?Yearbook . 1947 : 50.. 5.. FRIEDMAN, WALTER J. Jr. - 1949 - "Vermiculite: as-arSoil Amendment for Growth of Camellias!. Amer... Camellia?iYearbook 1949 1 64. 6. GARDNER, EDWARD J. - 194l - "Propagation!Under Mist?. Americans Nurseryman? 75(9) • 5 _ 77! 194l. JL GOSSARD, ATHERTON C. - 1944 - "The Rooting of Pecan Softwood" Cuttings:-Under Continuous ^ Miat"• . Proc.-. .Am. .Soc-. .Hort Sc-i., vol 44 « 251 . 8i••. HANGER, FRANCIS - 1947 - "Camellias-and Their. Cultured. Journal Royal Hort. Soc», vol. LXXII part .2": Feb;* 1947. 9. HITCHCOCK, A.E. - 1928 - "Effect of Peat Moss and Sand omRooting• Response; of Cuttings'!. Bot. Gazette* vol. LXXXVI : 121-148 t /28 . 10. HITCHCOCK, A.E., and--' ZIMMERMAN, P.W. - 1959 - "Comparative-Activity of Rootjrinducing-Substancesj and Me'thods-for Treating Cuttings-". Contrib.-BoycecThompson-Insti, 10(4) '. 461-480 : 1959. 11. HITCHCOCK, A.E., and ZIMMERMAN, P.W. - 1940 - "Effects?, Obtained! With .Mixtures: of Root ^ inducing and Other Substances^'. Contrib!. BoycerThompsonilnst., vol. l l ( l ) 1 46l-e480 : 1940. 12. HITCHCOCK, A.E., and-'ZIMMERMAN, P.W. - 1944 - "Comparative Root-Inducing Activity of Phenoxy Acids". Procr. .Am* Soc»Hort.. Sci., vol. .45 : 187 : 1944. 15.fc HYATT, ONES D. - 1947 - "Propagation:by Cuttiage". Amer. .Camellia:; Yearbook, 1947 : 51. 14. HYATT, ONIS D. - 1948 - "Rooting Responses-of Several Varieties? of Camelliaf?japonicafl. Amer. CamellianYearbook, 1948 : 90. 15. KAINS, M.G"., and McQUESTEN, L.M. - 1947 - "Propagationi of Plants!'. (revised edri)> Orange Judd? Co. Inci, N e w a r k , 1947* - 4 6 -Id. KEMP, E.E. - 19^ 8 - "Some Aspects of Plant Propagation-by Cuttings-,". Journal Royal Hot. Soc., vol. LXXIII part 9 : 29111 Sept.. 1948. 17i NEWTON, W., and LINES, C.J. - 1948 - "ThecRooting of Cypress and! Rose Cuttingss asc.'Influenced: by- Arasan? Fermate, and Spergonj and Each. Fungicideein Combination with; Naphthalene Acetic; Acidi". Scientific Agriculture*, vol 28 (12) * 574 : Dec* .1948. 18. PEARCE, HAROLD LESLIE - 1959 - "Plant Hormones-and Their Practical Importance;.in:Horticulture". Imperial Bureau offHort.. and; Plantation Crops, tech.-comm. no.12 t 1959* 19. SAWADA, K. - 1948 - " 1947 CamelliaaCutting Experimentsn. Amer. .Camellia-Yearbook 1948 » 95?' 20. SKINNER, H.T. - 1959 — "A New Propagation Methods for-Hybrid: Rhododendrons?'. Journal New;York Bot.-Gardens, vol XL : 471 : 85. 21. STOUTEMYER, V.T. - 1959 - "Talc as a Carrier offGrowth Substances-Inducing RootLFormatiominiSoftwood Cuttings". Proc. Am. Soc» Hort. Sci., vol. 56 : 817-822 : 1959. 22. STOUTEMYER, V.T. - 1944 - "The/Influences of Changes in .Molecular Configurations of Several NaphthyllGrowth' SubstancesBon the; Rooting Responses of Cuttings-". Proc. Am. Soc. Hort. Sci., vol. 44 » 529 : 1944. 25. STOUTEMYER, V.T., and O'ROURKE, F.L. - 1945 - "Rooting of Cuttings-from Plants^Sprayed'With Growth Regulating Substances". Proc- Am.' Soc. Hort. -Sci., vol. 4 6 : 407 : 1945. -25(a). STOUTEMYER, V.T., and: CLOSE, ALBERT W. - 1946 - "Plant .Propagation Under Fluorescent ..Lamps". U.S.D.A. Agric. Research Administration, Bureau of Plant Industry, Soils, and Agric. Engineering. Beltesville, Maryland. (Mimeographed circular). 24. SWANSON, HENRY F. - 1949 - "The Effect of Fungicidal Dips on; Rooting Camellia Cuttings". Amer. CamelliaaYearbook 1949 » 112. 25. WATKINS, J.V. - 1959 - "Propagating Tropical Shrubs byyLeaf-bud; Cuttings1'. Jour. N.Y. Bot* Gardens; vol. 40 (#78) : 229-255 : /59» 26. WATKINS, JOHN V. - 194? - "Leaf-bud Cuttings". Amer. Camellisa Yearbook, 1947 t 59. 27. WEST, ERDMAN - 1947 - "Camellia^Diseases? 1946:47 n. Amer. Camellia* Yearbook, 1947 t 117. 28. WHITE, HAROLD E. - 1946 - "Fermatecand its Effects; on Rooting of Geranium-Cuttings". Proc* AM. Soc. Hort. Sci., vol 47?» 522 ; 1946. 29. WILLIAMS, H. HAMILTON - 1945;- "Studies ram the Propagation of: Certain Broadd-leaf edi Evergreens,- With Special Referencecto Leaf-bud: Cuttings and Root-inducing SubstancesS. Proc. Am. Soc. Hort..Sci. vol 45 » 525-55O » 1945* 


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