In vitro formation and survival of appressoria of a mycoherbicide agent, Colletotrichum gloeosporioides f. sp. malvae and a benomyl-resistant strain, HP4.5RR

Abstract

Appressoria of the mycoherbicide agent Colletotrichum gloeosporioides f. sp. malvae (wild type and a benomyl-resistant mutant) were investigated in vitro . Appressoria formed on glass coverslips were dried and stored in darkness at 4 °C. After 1 wk, 1, 3 and 6 months the dried coverslips were plated onto PDA and benomyl-amended PDA. Appressoria germinated but there was a decrease in growth correlated to the length of time the dried coverslips were stored, indicating that appressoria function as survival structures. This might prove important for the efficacy of a mycoheribide under marginal weather conditions. Appressoria formed by a benomyl-resistant mutant strain showed reduced germination on benomyl-amended PDA, suggesting that perhaps appressoria are more sensitive to benomyl than the spores and hyphae.