Hema Kasinathan Thesis May 1 2012.pdf - Atrium - University of ...

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3.3.3 Growth room studiesThree experiments were conducted to investigate the interaction of host, growthmedium and pathotype on the efficacy of biofungicides on clubroot incidence andseverity, from November 2010 to September 2011 in a growth room at the University ofGuelph, Guelph, ON, Canada. Experiment 1 focused on the reaction of canola cv. 46A76(Pioneer Hi-Bred, Chatham, ON, Canada) to soil type, pathotype and biofungicide. Thiscultivar was selected because it is susceptible to pathotypes 3 and 6, and had beenassessed in the 2010 field trial. Experiment 2 focused on Shanghai pak choy cv. MeiQing Choi (Stokes Seeds Ltd., ON, Canada). Shanghai pak choy was selected because ithad been used previously to evaluate the efficacy of biofungicides to pathotype 6(Adhikari 2010), and the cultivar was highly susceptible to pathotypes 3 and 6.Experiment 3 focused on the impact of soil pore size. Each of the experiments wasrepeated.The first two experiments assessed the same factors in the same design, butfocused on canola (experiment 1) and Shanghai pak choy (experiment 2). Bothexperiments were conducted as four-replicate factorial randomized complete blockdesigns with three factors: a) soil type or growth media: muck soil, mineral soil, sand andsoil-less mix, b) biofungicides: Serenade, Prestop, a positive control (inoculated but nottreated with biofungicide) and a negative control (nontreated), and c) pathotype:pathotypes 3 and 6. Each experimental unit consisted of a minimum of 12 to 14 plants.To provide a comparison of the overall level of clubroot between Experiments 1 and 2,positive control treatments of canola on mineral soil and soil-less mix were also includedin the experiment on Shanghai pak choy.70
Four types of growth media were assessed: muck soil, pH 6.2 (Muck CropsResearch Station, ON), mineral soil, pH 6.8 (Bajar's farm south of Holland Marsh, ON),autoclaved noncalcareous coarse sand, pH 6.5 (Hutchenson Sand and Mixes, Huntsville,ON) and soil-less mix, pH 6.0 (Sunshine LB-2 Mix Basic, Sun Gro Horticulture CanadaLtd, Seba Beach, AB). The muck and minerals soils were tested for background levels ofinfestation with P. brassicae by growing Shanghai pak choy as a bait crop and noclubroot developed.The growth media were placed in individual tall plastic pots (164 mL Conetainers,Stuewe and Sons, Inc. Corvallis, OR). The seeds of canola and Shanghai pak choy weredirectly sown in the media for the muck and soil-less mix. However, it proved necessaryto transplant seedlings into the sand and mineral soil treatments because seed germinationin these two growth media was unacceptably low. The plants were maintained at 25°/20°C day/night, with 16-hr photoperiod and 65% relative humidity. The plants werefertilized with diluted 15:15:18 N:P:K solution at weekly intervals.Serenade and Prestop were applied 3 days before pathogen inoculation to allowtime for the biofungicides to colonize the roots. They were applied to 1-wk-old seedlingsof canola or Shanghai pak choy, at about the 1- to 2-leaf stage (fully expanded trueleaves). A drench application of 50 mL of the product solution was applied to eachseedling. It was expected that this volume was sufficient to saturate the rhizosphere zoneof the seedlings. The nontreated controls were drenched with 50 mL of water.Resting spores of pathotype 6 were extracted from the clubbed roots of cabbage thathad been collected from the Muck Crops Research Station in 2008 and stored at -20°C.71
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Influence of pH, Temperature, and B
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and Lee). The mean clubroot inciden
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TABLE OF CONTENTSACKNOWLEDGEMENTS .
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6 APPENDIX: 2 SUPPLEMENTARY TABLES
Page 10 and 11:
LIST OF ACRONYMSANOVABDCIAnalysis o
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pathogen in the Holland Marsh area
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1.2.1 PathotypesHonig (1931) was th
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were distinguished using only three
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1.3 HostsIn general, hosts of P. br
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erucic acid and 30 µmoles glucosin
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Table 1.2. Economically important B
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July and August. The temperature du
Page 27 and 28:
(Colhoun 1953). Studies on differen
Page 29 and 30: Soil compaction, which has been ass
Page 31 and 32: calcium source resulted in a small
Page 33 and 34: effective against P. brassicae has
Page 35 and 36: are filamentous rod-shaped gram-pos
Page 37 and 38: another study, the biofungicides Se
Page 39 and 40: Oomycetes and plasmodiophorids at v
Page 41 and 42: has been no systematic study of the
Page 43 and 44: 2 CHAPTER 2INFLUENCE OF pH AND TEMP
Page 45 and 46: The optimum temperatures for clubro
Page 47 and 48: When the cotyledons were fully expa
Page 49 and 50: the plants were watered with deioni
Page 51 and 52: dehisced sporangia looked like empt
Page 53 and 54: epetition. There was no repetition
Page 55 and 56: RHI = -169.14 + 27.54 (temp°) - 0.
Page 57 and 58: on canola seedlings at 12 days afte
Page 59 and 60: The individual regression analysis
Page 61 and 62: Multiple regression equations were
Page 63 and 64: hair infection was strongly and pos
Page 65 and 66: (Macfarlane and Last 1959, Myers an
Page 67 and 68: temperature (Adhikari, 2010, Gossen
Page 69 and 70: 3.2 IntroductionClubroot of crucife
Page 71 and 72: organic soil, whereas only 25% wate
Page 73 and 74: (1.34% Bacillus subtilis QST 713),
Page 75 and 76: 2. To assess the interaction of pat
Page 77 and 78: and the spray width was approximate
Page 79: 3.3.2 Field trials - Napa cabbageTw
Page 83 and 84: treatments (described in detail in
Page 85 and 86: Field capacity (%) =(Initial weight
Page 87 and 88: 3.4 Data analysisThe data were anal
Page 89 and 90: Analysis of variance was conducted
Page 91 and 92: etween clubroot severity and cumula
Page 93 and 94: growth medium) for severity, but no
Page 95 and 96: B) Saturated canola - Clubroot inci
Page 97 and 98: 10080A) Drained trialab ab bcaabPos
Page 99 and 100: 3.6.2 Experiment 2 - Shanghai pak c
Page 101 and 102: Table 3.5 Analysis of variance for
Page 103 and 104: A three-way interaction (biofungici
Page 105 and 106: correlated with micro-pore volume.
Page 107 and 108: negative correlation between clubro
Page 109 and 110: that a greater number of assessment
Page 111 and 112: supports the observations of previo
Page 113 and 114: In Experiment 3, both Prestop and S
Page 115 and 116: depending on factors such as soil m
Page 117 and 118: growth room trials, up to 6 x 10 9
Page 119 and 120: Biofungicides have been included as
Page 121 and 122: esults indicate that application of
Page 123 and 124: growth in rhizopshere zone (Mikkels
Page 125 and 126: iofungicides varies with the growth
Page 127 and 128: Bremer, H., B. Wehnelt, and E. Bran
Page 129 and 130: Dobson, R., R. L. Gabrielson, and A
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Hwang, S. F., S. E. Strelkov, B. D.
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Mitani, S., K. Sugimoto, H. Hayashi
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PMRA 2008. Registration Decision fo
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Tommerup, I. C., and D. S. Ingram.
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5 APPENDIX 1: ANOVA TABLES FOR CHAP
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Clubroot severity: Multiple regress
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7 APPENDIX 3: ANOVA TABLES FOR CHAP
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2011 - Root weight of 10 plantsSour
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Runs 1 and 2 combined DSIRandom eff
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Table. A3.9 Interaction of biofungi
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9 APPENDIX: 5 RAW DATA FOR CHAPTER
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CI- Clubroot incidence (%); - Not d
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25 7.0 3 43.66 4.33 15.89 20.33 56.
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10 APPENDIX 6 RAW DATA FOR CHAPTER
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Raw data for growth room trials Exp
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Soilless P6 Prestop 1 6.67 10.00 24
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Sand P3 Prestop 1 86.11 100.00 80.0
Page 165 and 166:
Mineral T5 - 1 80.00 50.00 70.00 43
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