WATER-CORN OIL EMULSION ENHANCES CONIDIA GERMINATION AND MYCOHERBICIDAL ACTIVITY OF COLLETOTRICHUM-TRUNCATUM

A water-corn oil (unrefined) emulsion has promise as a carrier for app lication of the mycoherbicide, Colletotrichum truncatum. We investigat ed this formulation (normal emulsion; oil in water) for influences on conidia germination, appressoria formation, and mycoherbicidal activit y of C. truncatum. Germination of conidia after application to hemp se sbania leaves was increased from 30% in water alone to 92% in the wate r-corn oil emulsion (water:oil, 1:1, by vol). The emulsion did not aff ect appressoria formation, Of the several other oils tested, safflower seed oil enhanced in vitro germination but did not enhance germinatio n and mycoherbicide activity when the conidia-emulsion formulation was applied to hemp sesbania leaves. Application of C. truncatum conidia in the unrefined corn oil emulsion to hemp sesbania seedlings resulted in 89 to 97% control of the weed after a 24 to 72 h dew delay. The em ulsion enhanced mycoherbicide efficacy by stimulating conidia germinat ion by protecting the conidia during a dew-free period, hence, increas ing weed infection when a dew occurred.