Herbicides, Intercropping system, Sugarcane, Sulfosulfuron, Weed control, Wheat
Sugarcane being a widely spaced crop offers considerable space for cultivation of short duration intercrop. In sub-tropical India, sugarcane planted in autumn accounts for higher productivity due to extended period (approximately 12–16 months) of vegetative growth, but its feasibility is only possible if some intercrop especially wheat in Rabi season is sown as it can help farmer in generating additional income in midway of sugarcane season. Two rows of wheat has already been recommended in the north – western India, but the success was marred due to lack of suitable weed control methods in sugarcane – wheat intercropping system. Twelve weed control treatments including ten applications with post-emergent herbicides i.e. sulfosulfuron 25 g/ha and 37.5 g/ha, pinoxaden 50 g/ha and 75 g/ha, readymade blend of sulfosulfuron + metsulfuron 30 g/ha and 45 g/ha, readymade blend of mesosulfuron + iodosulfuron 14.4 g/ha and 21.6 g/ha, metsulfuron 5 g/ha , carfentrazone-ethyl 20 g/ha, a weed free treatment with two hoeings at 3 and 6 weeks after sowing wheat (WASW) and an unweeded control (no hoeing and no herbicide application) were evaluated for three years from 2008-09 to 2010-11 in randomized block design with three replications. The objective of the experiment was to identify the best possible method of weed control for maximizing the productivity of sugarcane wheat intercropping system. All the chemical and cultural weed control treatments including the application of herbicides and manual hoeings suppressed the weeds efficiently as compared to the unweeded control. Among the herbicidal spray, application of sulfosulfuron 25 g and 37.5 g/ha recorded the lowest pooled dry matter of weeds and thus exhibited the highest weed control efficiency (mean of three years) (61.2% and 63.5%, respectively). The highest pooled cane equivalent yield of 92.7 t/ha was recorded with sulfosulfuron + metsulfuron 30 g/ha. Application of any herbicide at a higher dose than normal, could not supplement additional millable canes and sugarcane yield. Application of readymade blends of sulfosulfuron + metsulfuron 30 g/ha and mesosulfuron + iodosulfuron 21.6 g/ha produced pooled intercropped wheat yield of 3.41 and 3.49 t/ha which surpassed the 3.35 t/ ha of wheat yield achieved with two manual hoeings at 3 and 6 WASW. The cane quality was not affected by application of any herbicide.