Microbial Biopesticides' Efficacy in the Management of Tan Spot in Wheat

Tan spot, caused by Pyrenophora tritici-repentis, poses a significant threat to global wheat production, causing yield losses of up to 50% in susceptible cultivars. This study evaluated the efficacy of active ingredients in commercially available microbial biopesticides for managing tan spot under in vitro and greenhouse conditions. In vitro studies demonstrated complete inhibition of mycelial growth by Bacillus subtilis, Bacillus amyloliquefaciens, and Streptomyces lydicus, whereas hydrogen peroxide + peroxyacetic acid exhibited partial inhibition. In greenhouse trials, microbial biopesticides significantly reduced tan spot severity by 10 to 28% compared with untreated controls. Bacillus species showed the highest efficacy, aligning with previous findings on their antagonistic properties and induction of systemic resistance. These results suggest that microbial biopesticides could potentially be used as a tan spot management tool in an integrated pest management program.