Field Efficacy of Trichoderma-TM17 against Sheath Blight of Rice.

Rice sheath blight, caused by the soilborne fungal pathogen Rhizoctonia solani AG-1A, is an economically important disease in rice. Nearly 57% of Arkansas rice fields receive fungicides to suppress one or more rice diseases including sheath blight. Disease control using chemicals leads to increased risk to our environment. As an alternative option, biological control methods have gained interest in modern agriculture. As a result, several species in genus Trichoderma are known to be effective against fungal plant diseases. In this preliminary study, an experiment was designed in 2019 to test an isolate of Trichoderma atroviride (TM17) for seed dressing, and as a pre- and post-inoculation treatment to suppress sheath blight of rice. Seeds of long-grain rice, CL163 were soaked in a suspension of TM17, adjusted to 109 per ml spore concentration and dried under a sterile hood overnight before planting. Pre-inoculation treatment was sprayed on foliage at panicle initiation a week before R. solani AG-1A was inoculated. The post-inoculation treatment was applied a week after inoculation with 109 per ml spore concentration as in the seed treatment. Results showed that disease ratings were lower in foliage treated plots (pre- and post-inoculation treatments) than in the untreated control plots. Grain yields were also significantly higher in these plots than the untreated check. Plots planted with treated seeds showed a slightly lower incidence of disease than the control plots. Nevertheless, yield differences were not significantly different. The experiment should be repeated, refining the seed dressing method and on methodologies, particularly towards establishing TM17 in rice canopy throughout the season. [ABSTRACT FROM AUTHOR]