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ARS Home » Pacific West Area » Davis, California » Crops Pathology and Genetics Research » Research » Publications at this Location » Publication #307969
Title: Armillaria root rot

Author
item Baumgartner, Kendra
item RIZZO, DAVID - University Of California

Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: 6/15/2013
Publication Date: 10/15/2013
Citation: Baumgartner, K., Rizzo, D.M. 2013. Armillaria root rot. In: Bettia, L., editor. Grape pest management. 3rd edition. Oakland, CA: University of California, Division of Agriculture and Natural Resources. p. 83-86.

Interpretive Summary: First described on grapevines in California in the 1880s, the root disease ‘Armillaria root rot’ occurs in all major grape-growing regions of the state. The causal fungus, Armillaria mellea, infects woody grapevine roots and the base of the trunk (the root collar), resulting in a slow decline and eventual death of the vine. Armillaria root rot commonly affects vineyards planted on sites that were previously occupied by forests or orchards with infected trees. The fungus is commonly called ‘oak root fungus’, but it has no special affinity to oaks. Instead, the fungus infects over 500 species of trees. Native hosts include oaks and other common forest trees, such as Douglas-fir, California bay laurel, and madrone. The fungus also infects many orchard trees, including walnut, peach, and almond, as well as many woody landscape plants (e.g., rose). Armillaria root rot does not affect as many acres as do some other fungal diseases of grapevines (e.g., powdery mildew), but where it does occur, it is extremely difficult to eradicate from the soil and reduces yields throughout the life of an infected vineyard and that of successive plantings.

Technical Abstract: First described on grapevines in California in the 1880s, Armillaria root rot occurs in all major grape-growing regions of the state. The causal fungus, Armillaria mellea, infects woody grapevine roots and the base of the trunk (the root collar), resulting in a slow decline and eventual death of the vine. Armillaria root rot commonly affects vineyards planted on sites that were previously occupied by infected wild or cultivated hosts. Despite its common name of oak root fungus, A. mellea has a broad host range, infecting over 500 species of woody plants. Native hosts include oaks and other common forest trees such as Douglas-fir, California bay laurel, and madrone. The fungus also infects many cultivated plants, including walnuts and other orchard trees, as well as many woody landscape plants. Armillaria root rot does not affect as many acres as do some other fungal diseases of grapevines, but where it does occur, it is extremely difficult to eradicate and reduces yields throughout the life of an infected vineyard and that of successive plantings.