Bio – control of net-blotch and scald pathogens of barley using paenibacillus polymyxa KAI245 Isolated from sorghum rhizosphere in Western Kenya

Abstract

Net-blotch and scald are important foliar diseases of barley. In the present study, the biocontrol activity of Paenibacillus polymyxa KaI245 was evaluated against Drechsclera teres f. sp teres and Rhynchosporium commune causing net-form-net-blotch and scald respectively. In-vitro efficacy of the bacterial isolate entailed dual culture technique, use of cell-free supernatant and test for volatile-compounds-mediated inhibition. Greenhouse studies were further conducted to evaluate the efficacy of crude bacterial extracts against net-blotch pathogen in barley plants. In dual culture technique, the mycelial growth of D. teres f. sp teres was impeded by approximately 47.3% while there was no any observable effect in R. commune colonies. Food-poison technique was u sed to test the antifungal activity of cell-free supernatant. The cell free supernatant inhibited the growth of D. teres by approximately 24.1%. R. commune colonies were impeded by 52.9% via volatile organic compounds while D. teres f. sp teres remained unaffected. Greenhouse studies showed decreased disease incidence (50%) in the crude-extract-treated barley leaves inoculated with D. teres. In-vitro studies revealed that greater inhibition is imparted by live bacterial cells. The bacterium has the potential to be used as a biocontrol agent against the tested pathogens of barley. Use of bio-control agents to manage crop diseases is one of the alternatives set to replace chemical fungicides that are saddled with lots of negativity due to their hazardous environmental impact.