Evaluation of carfentrazone-ethyl+metsulfuron-methyl against broadleaf weeds of wheat

Several broadleaf herbicides are available for weed control in wheat, but alone they are not effective against all infesting weeds. Tank mixture often results in antagonism or crop injury, thus reducing crop yield. Field experiments were conducted at CCS Haryana Agricultural University during 2009_10 and 2010_11 to evaluate the efficacy of premix of carfentrazone-ethyl+metsulfuron-methyl (17.5 to 50 g/ha) with and without surfactant and compared with alone application of carfentrazone (20 g/ha), metsulfuron (4 g/ha) and 2, 4-D amine (500 g/ha) along with weedy check treatment. Premix of carfentrazone+metsulfuron at 25 g/ha+0.2% surfactant provided effective control of Malva parviflora, Lathyrus aphaca, Convolvulus arvensis, Rumex dentatus, Melilotus indica, Medicago denticulata, Anagallis arvensis, Coronopus didymus and Chenopodium album which were not effectively controlled by alone application of these herbicides. A non-ionic surfactant (NIS) was essential to increase the efficacy of carfentrazone+metsulfuron mixture. Premix of carfentrazone+metsulfuron 25 g/ha with 0.2% NIS reduced the population of weeds by 97_99% during 2009_10 and 2010_11, respectively, provided 95% control of infested weeds, reducing their dry weight by 98_99%, increasing tiller numbers by 26%, biological yield by 28% and grain yield of wheat by 31% over untreated control. Crop injury (5_15%) by the application of carfentrazone+metsulfuron with 0.2% NIS or carfentrazone alone was transient and caused no reduction in crop yield. The premix of carfentrazone+metsulfuron 25 g/ha+0.2% NIS had similar level of control to its higher rates of 30 and 50 g/ha, but was significantly better than alone application of 2, 4-D, metsulfuron or carfentrazone. In another field study, where Fumaria parviflora and Rumex spinosus were dominant weeds, tank mix of carfentrazone+metsulfuron 20+4 g with 0.2% NIS provided good control than their alone applications in a wheat field during 2009_10. The effect of tank mix application of carfentrazone+metsulfuron at 20+4 g/ha was similar to 600 g/ha of 2, 4-D amine and ester, but better than lower rates of 2, 4-D formulations. None of the 2, 4-D formulations was effective against R. spinosus, whereas metsulfuron, carfentrazone and their tank mix provided 85, 78 and 92% control of R. spinosus, respectively, and produced 41% higher tillers of wheat over untreated check. Similarly, tank mix of carfentrazone+metsulfuron 20+4 g/ha provided good control of F. parviflora in a fallow field during 2010_11. Alone application of carfentrazone or metsulfuron was not effective though plants treated with carfentrazone+metsulfuron recovered later on, but at later stages crop can smother it and the effect of tank mixture was similar to 600 g/ha of 2, 4-D ester, but better than its amine formulation and lower rates of 2, 4-D against this weed.