Target and non-target effect of commonly used fungicides on microbial properties in rhizospheric soil of rice

Sheath blight, caused by Rhizoctonia solani Kuhn, is a serious rice disease. Donors of resistance genes against R. solani could not be identified till date. Thus, fungicides are the only viable management option against R. solani. Seven strobilurin and triazole fungicides or fungicide mixtures were tested for their efficacy to combat R. solani along with their non-target effects on soil microbes for consecutive 2 years under field condition. Azoxystrobin at 125 g a.i. ha−1 was the most effective fungicide against R. solani followed by kresoxim-methyl at 250 g a.i. ha−1. During the first 7 days following fungicide application, microbial biomass carbon was inhibited. Seven days after fungicide application, fluorescein diacetate hydrolase was reduced, while dehydrogenase activity was not affected. Fungicides including azoxystrobin had a short-term negative effect on soil microbes, which subsequently recovered 30 days after application. The strobilurin fungicides could be used against R. solani without any negative effect on soil microbes.