Water-Corn Oil Emulsion Enhances Conidia Germination and Mycoherbicidal Activity ofColletotrichum truncatum

Abstract

A water-corn oil (unrefined) emulsion has promise as a carrier for application of the mycoherbicide,Colletotrichum truncatum.We investigated this formulation (normal emulsion; oil in water) for influences on conidia germination, appressoria formation, and mycoherbicidal activity ofC. truncatum.Germination of conidia after application to hemp sesbania leaves was increased from 30% in water alone to 92% in the water-corn oil emulsion (water:oil, 1:1, by vol). The emulsion did not affect appressoria formation. of the several other oils tested, safflower seed oil enhanced in vitro germination but did not enhance germination and mycoherbicide activity when the conidia-emulsion formulation was applied to hemp sesbania leaves. Application ofC. truncatumconidia 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 emulsion enhanced mycoherbicide efficacy by stimulating conidia germination by protecting the conidia during a dew-free period, hence, increasing weed infection when a dew occurred.