In vitro evaluation of fungicides, botanicals and bio-agents against Alternaria alternata causing leaf spot disease of niger

Abstract

Niger [Guizotia abyssinica, family:compositae] is commonly known as ramtil. It is minor oilseed crop. Under favourable condition niger is attacked by various diseases. Out of which, leaf spot caused by Alternaria alternata is one of the predominant disease of niger causes yield loss. The present investigation was carried out to test the efficacy of fungicides, botanicals and bio-agent in vitro against the Alternaria alternata. Among the fungicides tested carboxin + thiram was found most effective arresting 100% mycelial growth inhibition while carbendazim + mancozeb 93.15%, copper oxychloride 92.22%, propineb 90.00% and pyraclostrobin 80.37%. Bioefficacy of botanicals is tested by poisoned food technique and result revealed that maximum mycelial growth inhibition was recorded in turmeric rhizome extract 54.92% followed by neem leaf extract, garlic bulb extract, tulsi leaf extract and eucalyptus leaf extract 35.83%, 26.38%, 18.47% and 14.72% respectively. Among the bio-agents tested by dual culture technique Trichoderma reesei was found superior recorded 75.00% mycelial growth inhibition of Alternaria alternata followed by Pseudomonas fluorescens, bacillus subtilis and Trichoderma asperellum recorded 65.36%, 60.36% and 58.88% respectively.