Management of Alternaria leaf blight of groundnut caused by Alternaria alternata

Groundnut (Arachis hypogaea L.) leaf blight caused by Alternaria alternata (Fr.) Keissler was observed in South Gujarat region during the year 2015–2016 in both the seasons summer and kharif. The associated pathogen was identified. Five bio agents tested by dual culture technique and nine fungicides were tested at different concentrations (250, 500, 1000 ppm) by poison food technique in invitro condition. Trichoderma viride was found most effective in inhibiting the mycelial growth of Alternaria alternata followed by T. harzianum. In case of fungicides propiconazole and hexaconazole (250 ppm) showed cent per cent growth inhibition, tebuconazole and difenconazole + azoxyistrobulin gave 100% growth inhibition at 500 ppm concentration. Among these four fungicides and two bio-agents which were most effective under in vitro condition were tested in field condition and recorded the disease severity and pod yield. Hexaconazole gave maximum disease control (52.44%) followed by propiconazole and tebuconazole. Highest pod yield (1783 kg/ha) was recorded in tebuconazole followed by hexaconazole (1623 kg/ha) with highest haulm yield (5090 kg/ha) in Kharif season. Whereas in Summer season hexaconazole also gave maximum disease control (58.69%) followed by propiconazole and tebuconazole. Highest pod (2767 kg/ha) and haulm yield (8749 kg/ha) was recorded in hexaconazole followed by propiconazole has gave 2662 and 8532 kg/ha pod and haulm yield respectively. Moreover Hexaconazole was found superior to all the tested fungicides as well as bio-agents during both the seasons in relation to reduction of Alternaria leaf blight disease severity of groundnut and gave highest pod and haulm yield kg/ha. © 2018, Indian Phytopathological Society.