Bioefficacy of propiconazole alone or in combination with other fungicides against Alternaria alternata causing leaf blight in cowpea

In the present study, the bioefficacy of propiconazole alone or in combination with other fungicides was evaluated for the management of Alternaria leaf blight in cowpeas under in vitro and field conditions. For this, propiconazole was employed in different fungicidal combination (viz., propiconazole 25 EC + chlorothalonil 75WP, propiconazole 25 EC + propineb 70 WP and propiconazole 25 EC + metiram 60 WG) with standard fungicidal check (viz., propiconazole 25 EC, tebuconazole 50 + trifloxystrobin 25 WG, pyraclostrobin 5 + metiram 55 WG and carbendazim 25 + mancozeb 50 WS) along with native isolate of Trichoderma spp. and untreated control. Among all fungicides, the mean colony diameter observed ranged from 0.00 to 31.68 mm at different concentrations of different fungicides with the mean growth inhibition ranging from 63 to 100%. The maximum 100% mean growth inhibition was recorded in propiconazole 25 EC, while a minimum 63% mean growth inhibition was recorded in carbendazim 25 + mancozeb 50 WS with 31.7 mm colony diameter under in-vitro condition. Among all the treatments, the highest reduction in disease incidence was observed in tebuconazole 50 + trifloxystrobin 25 WG with 71.6% disease reduction which was at par with propiconazole 25 EC + metiram 60 WG and propiconazole 25 EC + chlorothalonil 75WP with 70 and 62% disease reduction, respectively. The least effective treatment recorded pyraclostrobin 5 WG + metiram 55 WG with 33% disease reduction but effective over the control.