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K. NALINI* AND C. CHINNUSAMY
Instructional Livestock Farm Complex, Veterinary College and Research Institute, Tirunelveli, Tamil Nadu, India.
Weeds are considered as a major biotic constraint for high production. The weeds which germinate before or simultaneously with the crop are frequently capable of forming a leaf canopy over cotton. To manage the weeds effectively the present study was taken during winter seasons of 2008-09 and 2009-10 at Tamil Nadu Agricultural University, Coimbatore. Field trials were laid out in randomized block design with treatments replicated thrice. In the present study, various weed management practices viz., pre-emergence pendimethalin 38.7 per cent EC at 1.5, 2.0, 2.5 and 4.0 kg ha-1 + hand weeding, pendimethalin 30% EC at 1.0 kg ha-1 + hand weeding, Early post emergence trifloxysulfuron at 10g ha-1 + hand weeing, pre emercence pendimethalin 30% EC at 1.0 kg ha-1 + power weeder weeding, pendimethalin 30% EC at 1.0 kg ha-1 + crop residue mulching + hand weeding, power weeder weeding on 25 and 45 DAS, hand weeding twice, weed free and unweeded checks were included. The results showed that weed control efficiency (WCE) was maximum under pre-emergence application of pendimethalin (38.7%) at 4.0 kg ha-1 at 25 and 45 DAS. Pre-emergence application of pendimethalin registered higher WCE ranging between 93.45 and 65.8 per cent. The weed free check with maximum yield was taken as the base to work out the weed index that gives the magnitude of yield reduction due to weed competition in other treatments. The highest yield reduction of 51.7 and 103 per cent occurred under unweeded control during winter 2008-09 and winter 2009-10, respectively.
Cotton, Pendimethalin, Weed control efficiency, Weed Index, SDR