Vegetable oil suspension emulsions reduce dew dependence of a mycoherbicide

Abstract

The use of vegetable oil suspension emulsions in controlled-environment conditions to reduce dew dependence in the mycoherbicide based on the fungus Colletotrichum orbiculare to control the weed Xanthium spinosum is reported. Spores of C. orbiculare were dried with kaolin to produce a powder containing 1 × 10 9 spores g −1. The dried powder was mixed with one of several commercial vegetable oil products (canola, peanut, safflower, soybean, corn and sunflower) and an emulsifying agent Latron (modified phthalic glycerol alkyd resin) to give a final composition of 10% oil, 1% Latron, 89% water and 1 × 10 6 spores ml −1. The oil suspension emulsions were applied to X. spinosum without dew (50–55% relative humidity) and compared with an aqueous suspension with and without dew. All of the oil formulations were a significant improvement over the aqueous suspension without dew. There were no significant differences between oils, but canola oil appeared to be the most promising.