Fungicidal management of web blight of urdbean caused by Rhizoctonia solani

Web blight caused by Rhizoctonia solani causes huge yield loses in urdbean (Vigna mungo). All the commercially grown varieties are susceptible. Hence, more than ten fungicides were evaluated as foliar sprays during kharif season 2005, 2007-2010 using susceptible variety UL 338. Two foliar sprays of fungicides, namely; hexaconazole 5EC (Contaf 5EC)@ 0.1%, difenconazole 25EC (Score 25EC) @ 0.05%, carbendazim 50WP (Bavastin 50WP) @ 0.1% and propiconazole 25EC (Tilt 25EC) @ 0.1% significantly reduced the disease severity resulting in 81.1, 80.6, 65.9 and 76.2% control over unsprayed check with corresponding mean yield of 872, 821, 791 and 754 kg/ha compared with the mean yield of 584 kg /ha in unsprayed control . The net benefit for the two foliar sprays of hexaconazole 5EC, difenconazole 25EC, propiconazole 25EC and carbendazim 50WP and chlorthalonil 50WP, has been worked out to be Rs.10229, 6891, 6375, 4524 and 3274, respectively for the crop grown for the grain purpose (@Rs. 4300/q) with the cost: benefit ratio of 5.8, 3.1, 2.6, 4.0 and 1.8, respectively. In the crop, grown for the breeder seed purpose (Rs.12000/q), the net profit for foliar sprays of hexaconazole 5EC, difenconazole 25EC, propiconazole 25EC, carbendazim 50WP and chlorthanonil was worked out to be Rs.32405, 25140, 17616, 22614 and 16980 respectively with cost: benefit ratio of 16.0, 8.6, 7.3, 11.2 and 4.9, respectively. The same trend was observed for foundation and certified seed also. The fungicides were effective in reducing the severity of powdery mildew also.