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United States Department of Agriculture

Agricultural Research Service

Title: A Soil Inoculant Inhibits Armillaria Mellea in Vitro and Improves Productivity of Grapevines with Root Disease

Authors
item Baumgartner, Kendra
item Warnock, Amy

Submitted to: Plant Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 1, 2005
Publication Date: April 1, 2006
Citation: Baumgartner, K., Warnock, A.E. 2006. A soil inoculant inhibits armillaria mellea in vitro and improves productivity of grapevines with root disease. Plant Disease.

Interpretive Summary: A commercial product known as Vesta® (Biologically Integrated Organics, Inc., Sonoma, CA) was tested for its ability to limit the growth of the fungal root pathogen, Armillaria mellea, the causal agent of Armillaria root disease. Armillaria root disease of grapevine is difficult to control, even with the aid of toxic chemicals, such as methyl bromide. The appeal of Vesta is that it is made by fermenting several different types of composted material and, therefor, is a relatively safe product. We found that both Vesta and bacteria cultured from Vesta significantly decreased the growth of the pathogen. Efficacy of Vesta for postinfection control of Armillaria root disease of grapevine was examined in a diseased vineyard in Northern California. For treated rows, Vesta was applied to the soil via the drip-irrigation system to multiple rows in the vineyard in 2003 and 2004. Nontreated rows received irrigation water instead of Vesta. We collected measurements of yield, growth, nutrition, and grape juice quality from healthy and symptomatic vines in treated and nontreated vinerows. Vesta significantly increased cluster weights of symptomatic vines to levels equal to those of healthy vines. However, Vesta did not decrease the rate of symptom development or mortality of treated vines and, therefore, may not provide long-term control of Armillaria root disease. Our findings of decreased nutrient concentrations, and lower sugar content in fruit from symptomatic vines demonstrate that Armillaria root disease negatively affects vine nutrition and fruit quality.

Technical Abstract: A commercially available soil inoculant, Vesta® (Biologically Integrated Organics, Inc., Sonoma, CA), was tested for its ability to inhibit Armillaria mellea, the causal agent of Armillaria root disease. Undiluted inoculant and bacterial isolates cultured from the inoculant (Bacillus subtilis, B. lentimorbus, Comamonas testosteroni, Pseudomonas aeruginosa, P. mendocina) significantly inhibited colony diameter of A. mellea. Efficacy of the inoculant for postinfection control of Armillaria root disease of grapevine was examined in an A. mellea-infested vineyard in Northern California. Inoculant was applied to the soil via the drip-irrigation system to vinerows in replicate blocks in 2003 and 2004. Yield, growth, mineral nutrition, and juice quality parameters of healthy and symptomatic vines were measured in treated and nontreated vinerows. The inoculant significantly increased cluster weights of symptomatic vines to levels equal to those of healthy vines. However, the inoculant did not decrease the rate of symptom development or mortality of treated vines and, therefore, may not provide long-term control of Armillaria root disease. Our findings of decreased petiole P and K concentrations, and lower soluble solids content in fruit from symptomatic vines demonstrate that Armillaria root disease negatively affects vine mineral nutritional status and fruit quality.

Last Modified: 7/31/2014
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