Efficacy of biocontrol agents and chemicals against early blight of potato caused by Alternaria Spp.

AbstractThe effect of biocontrol agents and chemicals against early blight of potato caused by alternaria spp was studied. Treatments of foliar spray of Pseudomonas fluorescens, Trichoderma harzianum, Trichoderma viride, Trichoderma asperellum, copper oxychloride 50% WP, azoxystrobin 18.2% SC + difenoconazole 11.4% SC and hexaconazole 5% SC, all @ 0.2%, were applied at the first initiation of disease symptoms. Results showed that the disease severity was significantly lower in hexaconazole 5% SC (23.2%) followed by azoxystrobin 18.2% + difenoconazole 11.4% SC (25.9%). Under In vitro condition, dual culture technique was used to check the efficacy of different bio-agents whereas poisoned food technique was used to assess fungicidal efficacy of chemicals against Alternaria sp.. Among bio-agents, the best inhibition was shown by Trichoderma harzianum (82.8%) followed by Trichoderma viride (81.3%) and least effect showed in Trichoderma asperellum (78.8%). Among fungicidal chemicals, the best inhibition result was found in hexaconazole 5% SC (91.7%) followed by azoxystrobin 18.2% + difenoconazole 11.4% at 100 ppm (86.5%) concentration.