Growth, reproduction, and toxin production of Phomopsis sojae Lehman in culture

The role of Phomopsis sojae in the soybean field and in seed decay has been well investigated. The production of toxins by this fungus, not previously reported, was examined in this study. Dilutions of P. sojae culture filtrates, derived from 14 - 29 day old cultures, significantly affected soybean seed germination; 1/10 and 1/100 dilutions inhibited soybean seedling root elongation. A dilutable phytotoxin was produced by P. sojae in culture.

The fungus grew well on six of seven media tested at temperatures ranging from 10 - 30°C. Pycnidial formation in culture occurred infrequently and depended on incubation periods of 35 days or longer.