Integrated weed management in maize (Zea mays)

A field experiment was conducted at Almora during 1994–96 to find out most effective control measure for weeds in rainy-season maize (Zea mays L.) under rainfed conditions. Pre-emergence atrazine (1.25 kg/ha), pendimethalin (1.50 kg/ha) and alachlor (2.00 kg/ha) alone and in combination with 3 post-emergence (30 days after sowing) control measures, viz. hand-weeding, paraquat (0.50 kg/ha) and earthing up the crop were compared with weed-free and weedy check treatments. None of the pre-emergence herbicides alone provided desired control of weeds. However, alachlor proved most effective [weed-control efficiency (WCE) 65.0%], followed by pendimethalin (WCE 63.1%) and atrazine (WCE 58.9%). Atrazine was more effective against Ageratum conyzoides L. and less effective against Echinochloa colonum (L.) Link and Brachiaria ramosa stapf than pendimethalin or alachlor. Inclusion of all post-emergence weed-control measures in any pre-emergence herbicide markedly improved WCE, yield attributes and grain yield. However, earthing up the crop proved most effective, followed by hand-weeding and paraquat. Highest grain yield (4,080 kg/ha), superior yield attributes, net return (Rs.4,585/ha) and benefit: cost ratio (1.30) were recorded under alachlor+earthing up the crop. This treatment being at par with weed-free also had higher WCE than all treatments.