armillaria root rot, worldwide fungal disease which lives in woody plant materials in the soil and attacks a wide range of plants including vines. It is sometimes called the mushroom, oak, or shoestring root rot. It is typically a problem on land where vines have replaced trees, and is frequently seen in new California vineyards where oak trees grew previously. Infected vines tend to occur in groups and slowly decline or sometimes die suddenly. The causal fungus, Armillaria mellea, produces white fungal mats with a distinct mushroom-like smell under the bark of the vine’s lower trunk and roots. The land can be fumigated to ward off this fungus, for which there are no tolerant rootstocks.
