Effect of bioagents and chemicals for the management of aerial blight and dry root rot of blackgram incited by Rhizoctonia bataticola

Abstract

Blackgram ( Vigna mungo L.) is an important pulse crop grown throughout India. A new disease of blackgram i.e. aerial blight and dry root rot caused by Rhizoctonia bataticola is primarily a soil inhabitant. An attempt was made to manage the disease with biocontrol agents and fungicides. Among the biocontrol agents tested against Rhizoctonia bataticola, Pseudomonas fluorescens (DAPG +ve )-RP46 was found more effective as compared to other bio-control agents and inhibited maximum mycelia growth (68.95%) of R. bataticola followed by T. harzianum (Th-R) (61.85%) and T. viride (Tv-R) (61.11%) under in vitro condition. Fungicides like contact, systemic and combi products were also tested against the aforementioned pathogen. Among five contact fungicides captan, propineb and zineb recorded cent per cent inhibition (100%) of mycelial growth at all the concentrations (i.e., 0.1, 0.2 and 0.3%) among seven systemic fungicides and combi fungicides tested, benomyl, carbendazim, hexaconazole, thiophanate methyl and tridemefon showed 100 per cent mycelia inhibition and also in carbendazim 12% + mancozeb 63%, cymoxanil 8%+ mancozeb 64%, captan70% + hexaconazole 5 %, tricyclozole 18% + mancozeb 62% and mancozeb (64 %) + metalaxyl (4 %) showed cent per cent (100%) inhibition at all the concentrations (0.05, 0.10 and 0.2%), respectively. The maximum vigour index of 2652.83 was recorded in Pseudomonas fluorescens (+DAPG)- RP46 treated blackgram seeds followed by 2042.00 and 1997.80 vigour index in Trichoderma harzianum -II(R) and T. viride - II(R) and poor vigour index of 1258.00 was observed in untreated control.