Biological Control of Phytophthora Root Rot of Soybean by Hyphochytrium catenoides in Greenhouse Tests

Abstract

AbstractMycelia of Hyphochytrium catenoides applied to soil artifically or naturally infested with Phytophthora megasperma var. sojae was effective in affording a high degree of protection of soybean plants against root rot in greenhouse tests. Seedling emergence, plant height and root diseases were restored to values near those of plants grown in soil without the pathogen, and root disease severity was greatly reduced, though never eliminated. Control was similar whether soil was treated with H. catenoides, then folded for 7 days before seeding, or if the flooding and prior incubation periods were eliminated. Abundant inoculum of H. catenoides was produced in a semi‐solid medium containing tryptone, glucose and yeast extract in which the colonies remained suspended. The inoculum, applied to vermiculite and stored in the laboratory, survived well: colony counts after 25 weeks were 63% of those present initially.