Chemical control of weeds in autumn planted sugarcane + wheat intercropping system.
The efficiency of weed control by pre-em. application (2-3 days after sowing (DAS)) of 0.75 or 1.0 kg/ha isoproturon and 0.75 kg/ha pendimethalin, post-em. application (30 DAS) of 1.0 kg/ha isoproturon and 1.31 kg/ha methabenzthiazuron, and hoeing twice at 30 and 60 DAS was studied in a wheat-sugarcane intercrop grown at Kheri, Sangrur (India), during 1986-87 and 1987-88. Two rows of wheat cv. HD2329 were sown between 2 rows of sugarcane on 11 November 1986 and 5 November 1987. The dominant weed species were Phalaris minor, Chenopodium album, Silene conoidea, Lepidium sativa [L. sativum], Melilotus indica, Medicago denticulata and Anagallis arvensis. Field studies revealed that post-em. application of 1.0 kg/ha isoproturon gave a wheat grain yield of 4.0 t/ha compared to 3.0-3.4 t/ha for hoeing twice and other herbicides. Post-em. application of 1.0 kg/ha isoproturon was the best herbicide treatment in terms of wheat grain yield and cane yield (56.3 t/ha), due to higher weed control efficiency (64.78%, compared to 54.15-57.72% with other herbicide treatments and 71.18% with hoeing). None of the herbicides was toxic to either of the crops.