BIOLOGICAL CONTROL OF ARMILLARIA ROOT DISEASE OF GRAPEVINE

Authors: Baumgartner, Kendra; WARNOCK, AMY - USDA, ARS, CPGRU

Submitted to: American Phytopathological Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: 8/1/2006
Publication Date: 8/1/2006
Citation: Baumgartner, K., Warnock, A. 2006. Biological control of armillaria root disease of grapevine. American Phytopathological Society Abstracts.

Interpretive Summary: Armillaria root disease causes significantly lower yield and growth, lower root absorption of nutrients from the soil, delayed ripening of fruit, and eventual death of grapevines infected with Armillaria mellea. We pursued a novel tactic for control of the disease with Vesta (BIO, Sonoma, CA), a soil inoculant containing a mixture of bacteria that are antagonistic to the pathogen. Vesta was applied via drip-irrigation (47 liters/ha at budbreak and bloom, 19 liters/ha at 15% and 85% veraison) to vineyard rows in three separate sections of a Cabernet Sauvignon vineyard for two years. We measured yield, growth, nutrition, and juice quality of 12 healthy and 12 symptomatic vines in treated and nontreated rows of each section. Symptomatic vines treated with Vesta had significantly higher cluster weights (109.63 g) that were comparable to those of healthy vines (122.09 g), which shows that Vesta can restore cluster weights to normal levels, an important factor for wine quality. Vesta had no stimulatory effect on healthy vines, suggesting that its efficacy is a function of its effects on the pathogen. Vesta and bacteria cultured from it (e.g. Pseudomonas aeruginosa) on yeast malt extract agar significantly inhibited the pathogen in inhibition assays. Our results indicate that Vesta is therapeutic to infected vines and that antagonistic bacteria may contribute to its efficacy. Studies are underway to identify additional antagonistic bacteria in Vesta and to characterize their modes of action.

Technical Abstract: Armillaria root disease causes significantly lower yield and growth, lower root absorption of macronutrients, delayed ripening of fruit, and eventual death of grapevines infected with Armillaria mellea. We pursued a novel tactic for control of the disease with Vesta (BIO, Sonoma, CA), a soil inoculant containing a mixture of antagonistic bacteria. Vesta was applied via drip-irrigation (47 liters/ha at budbreak and bloom, 19 liters/ha at 15% and 85% veraison) to vinerows in three blocks of a Cabernet Sauvignon vineyard for two years. We measured yield, growth, nutrition, and juice quality of 12 healthy and 12 symptomatic vines in treated and nontreated sections of each block. Symptomatic vines treated with Vesta had significantly higher cluster weights (109.63 g) that were comparable to those of healthy vines (122.09 g), which shows that Vesta can restore cluster weights to normal levels, an important factor for wine quality. Vesta had no stimulatory effect on healthy vines, suggesting that its efficacy is a function of its effects on the pathogen. Vesta and bacteria cultured from it (e.g. Pseudomonas aeruginosa) on yeast malt extract agar significantly inhibited the pathogen in inhibition assays. Our results indicate that Vesta is therapeutic to infected vines and that antagonistic bacteria may contribute to its efficacy. Studies are underway to identify additional antagonistic bacteria in Vesta and to characterize their modes of action.