Biological Control of the Weed Sesbania exaltata Using a Microsclerotia Formulation of the Bioherbicide Colletotrichum truncatum

Abstract

Colletotrichum truncatum, grown on rice grain (3 to 4 weeks, 22˚C to 24˚C) produced a fungus-infested rice mixture of microsclerotia and conidia (spores) in a ratio of ~9:1, respectively. Greenhouse tests of this formulation (0.4 to 50 mg finely-ground fungus-rice product) which applied pre-emergence to 5 cm2 of soil surface, caused 22% to 96% hemp sesbania plant mortality, after 14 days. Post-emergence treatment (fungus-rice aqueous formulation; 2.4 × 105 microsclerotia ml−1, 30% unrefined corn oil and 0.2% Silwet L-77 surfactant) of weeds surviving the pre-emergence application, resulted in 93% mortality, after 14 days.