Bioefficacy of Imazethapyr Applied Alone and in Combination with other Herbicides in Black Gram and their Residual Effect on Succeeding Pearl-millet and Sorghum Crops

Abstract

Background: Weeds are one of the major constraints in achieving yield potential of black gram. Due to slow initial growth of black gram, weeds compete effectively and caused reduction in growth as well as yield of black gram. Hand weeding is neither practicable nor economical due to unpredictability of weather and high labour cost, respectively. Therefore, application of herbicides is considered as the best approach for efficient weed control in black gram. Methods: A field experiment was conducted at Research Farm of Department of Agronomy, CCSHAU, Hisar during summer and kharif 2017 to evaluate the effect of different weed control treatments in black gram and their residual effect on succeeding pearl millet and sorghum crops. Total of fourteen weed control treatments were replicated thrice in randomized complete block design (RCBD).Result: Dactyloctenium aegyptium (37%), Trianthema portulacastrum (34%), Cyperus rotundus (21%) and Digera arvensis (8%) were the major weed flora associated with black gram at 30 DAS. Both at 30 and 60 DAS, PE application of imazethapyr + pendimethalin (RM) at 1000 g ha-1 provided 100% control of D. aegyptium and T. portulacastrum. PE application of imazethapyr + pendimethalin (RM) at 1000 g ha-1 was the most significant herbicide treatment (90% control of weeds) at 30 DAS however, 3-4 leaf stage application of imazethapyr + imazamox at 70 g/ha recorded with highest control of weeds (89%) at 60 DAS. Maximum seed yield (912 kg ha-1) and yield attributes of black gram were obtained in weed free treatment which was statistically at par with two hoeing performed at 20 and 40 DAS (895 kg ha-1) and PE application of imazethapyr + pendimethalin (RM) at 1000 g ha-1 (878 kg ha-1). Imazethapyr and its RM combination with imazamox applied at 3-4 leaf stage had phytotoxic effects on black gram at 30 DAS which suppressed the growth and caused yield penalty. Residual effect or phytotoxicity was not observed on succeeding pearl millet and sorghum crops.