ISHS Acta Horticulturae 695: I International Symposium on Tomato Diseases
EVALUATION OF BIOLOGICAL CONTROL OPTIONS FOR BACTERIAL SPOT MANAGEMENT DURING TOMATO TRANSPLANT PRODUCTION |
| Authors: | G. Briceno-Montero, S.A. Miller |
| Keywords: | Xanthomonas axonopodis pv. vesicatoria, processing tomato, seedlings, bacteriophage, BioYield, Pseudomonas fluorescens B56, Pseudomonas syringae Cit7, Bacillus amyloliquefaciens, Bacillus subtilis, acibenzolar-S-methyl, Actigard |
| Abstract:
Transplanting greenhouse-germinated tomato seedlings is the predominant means of initiating field production in many regions. Bacterial leaf spot can cause severe losses in tomato seedlings and greatly impact commercial tomato production. To manage this disease, transplant producers routinely apply copper compounds, often mixed with mancozeb. Twenty-six alternative treatments were evaluated for efficacy against bacterial leaf spot on fresh market tomato seedlings. Acibenzolar-S-methyl, Bacillus amyloliquefaciens, B. subtilis, Pseudomonas syringae Cit7, P. fluorescens B56, strain specific bacteriophages and the standard copper-mancozeb treatments were applied alone or in combination. Copper-sensitive Xanthomonas vesicatoria strains were used to inoculate 4-week-old fresh market tomato seedlings under greenhouse conditions. Visual disease severity assessment was performed using a six-level rating scale adapted from the Horsfall-Barrat system. Acibenzolar-S-methyl provided significantly better (p = 0.0001) control than the standard copper-mancozeb treatment, reducing bacterial leaf spot incidence and severity to values as low as 17% and 0.4%, respectively. Although B. amyloliquefaciens, B. subtilis, and P. syringae Cit7, in combination with other treatments, were generally among the most effective treatments, they did not reduce incidence or disease severity when applied alone. Pseudomonas fluorescens B56 and bacteriophages were not effective. | |
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