Effect of Bacillus Mycoides Supplement in a Reduced Frequency Fungicide Program on Chambourcin Grapevines.

Fungal diseases pose significant challenges for grapevine producers in Kentucky due to the region’s abundant moisture and relative humidity. Methods to reduce fungicide application frequency would prove both economically and temporally valuable to producers. A field experiment was established in Bowling Green, KY in 2017 to investigate Bacillus mycoides isolate J (Lifegard) as a supplement to a fungicide program for Induced Resistance (IR). Three fungicide treatment regimens were implemented consisting of a traditional fungicide program modelled from the Midwest Fruit Pest Management Guide and an identical program supplemented with 140 g ha^-1 Lifegard per application (both applied on 14 day intervals), a reduced frequency application every 28 days supplemented with 140 g ha^-1 Lifegard, and an untreated control. Treatments were applied to 9-year-old French-Hybrid grapevines (cv. Chambourcin); each treatment was replicated 3 times in a randomized complete block design. All treatments were applied with a backpack sprayer delivering 150 L ha^-1 at 2 Bar pressure. Canopy management, fertility, herbicide, and insect management were standardized across treatments and no supplemental irrigation was applied. Data collected included fruit yield, pH, Brix, and Titratable Acidity (TA). Data was analyzed with SAS PROC GLIMMIX; differences in means were determined at P < 0.05. Plots supplemented with B. mycoides had lower fruit pH than untreated plots but higher fruit pH than the traditional fungicide program. Treatment regime did not influence Brix, TA, or yield; however, treated plots exhibited less visual disease symptoms.