Abstract
The effects of methionine treatment on damping-off caused by Aphanomyces cochlioides in greenhouses, and the growth of hyphae and germ tubes in culture were studied. Application of 420-600 ppm methionine to seedlings 7 days after sowing resulted in significant reduction of infestation of sugar beet plants by A. cochlioides in an artificially inoculated soil test. In zoospore inoculation tests, application of 200-600ppm methionine one day before inoculation reduced the severity of damping-off. The colony diameter of A. cochlioides on PDA treated with 420 ppm methionine was reduced to 97.9% of that on PDA without methionine. The length of the germ tube from the zoospore in 400 ppm methionine solution for 24 hours was 24% of that treated with distilled water. These results suggest that suppression of damping-off by methionine is partly caused by suppression of the growth of germ tubes and hyphae during A. cochliides infection.
