Negative effect of three commonly used seed treatment chemicals on biocontrol fungus Trichoderma harzianum

Abstract

Successful integration of biocontrol organisms into agricultural production systems requires knowledge of their compatibility with commonly used pesticides. The compatibility of the biocontrol fungus Trichoderma harzianum (Eco-T ®) with a pesticide mix containing imidacloprid, metalaxyl and thiram (Product X) was assessed for maize seed treatment. Laboratory evaluations demonstrated that Product X caused up to 97.6% mortality of T. harzianum in a period as short as 3 days after seed treatment. Under greenhouse conditions, combined treatment of T. harzianum and Product X resulted in a significant reduction in percentage germination, dry shoot biomass and maize vigour when compared to single treatment with T. harzianum. Seed treatment with T. harzianum significantly enhanced maize germination, dry shoot biomass and vigour. In contrast, treating maize seed with Product X showed no actual benefit towards optimizing maize seedling growth.