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Ecological and Genetic Diversity of Soilborne Pathogens and Indigenous Microflora
K.W. Seebold, M. Elliott, C. Canaday, C. Rothrock, A. Westphal, T. Keinath
Department of Plant Pathology
Vegetables and ornamentals are important crops grown in the southeastern US and suffer from a number of disease problems. The use of biological agents to manage diseases in these crops would offer an effective, sustainable, and evironmentally sound approach to management of disease. The purpose of this project is to evaluate biological agents for suppression of root diseases common to vegetable crops and bedding plants.
2011 Project Description
A trial was conducted in the summer of 2011 to evaluate Tenet, a commercial formulation containing Trichoderma harzianum and T. viride, for suppression of Phytophthora blight, caused by Phytophthora capsici, on summer squash when applied to seedlings prior to transplanting or to soil via drip irrigation, alone or in conjunction with fungicide programs.
Earlier results showed that Tenet-containing treatments reduced the severity of Phytophthora blight by 25% over the untreated control; however, results from the 2011 study differed. Tenet, when applied to squash seedlings one week prior to transplanting, reduced overall severity of Phytopthora blight compared to the untreated control. Treatments applied in the field had no effect - a departure from the trial conducted in 2009. This work with carried out in conjunction with P. Ji of the University of Georgia.
Two trials were conducted over two seasons at each location. In 3 out of the 4 trials (two on pepper and one on summer squash), significant suppression of Phytophthora blight on pepper or summer squash resulted from the application of Tenet (Bioten) WP before and at-transplanting. In the fourth trial, overall severity of disease was low (likely due to conditions that did not favor Phytophthora blight) and no clear-cut conclusions could be drawn regarding the performance of Tenet. In that trial, the efficacy of Tenet was not consistent across all biopesticide-conventional fungicide combinations, but a slight level of disease suppression was observed.
Testing commercial a formulation of Trichoderma viride & T. harzianum (Tenet WP) as a soil drench or transplant treatment was shown to provide significant suppression of Phytophthora blight in 3 out of 4 trials (2 in Kentucky, 2 in Georgia) over a two-year span. Efficacy of the biopesticide does not equal that seen for commercial pesticides; however, it does appear that Tenet has potential to serve as an adjunct for traditional fungicides used for management of Phytophthora blight that could help enhance the performance of these products and provide greater returns to vegetable producers.