Weed control in maize (Zea mays L.) with pre and post-emergenceherbicides

Studies were undertaken to determine the effect of some pre and postemergence herbicides on weed control and maize yield at Agricultural ResearchInstitute, Tarnab during 2001 and 2002. In 2001, pre and post- emergenceherbicides were tested in one trial and in 2002, pre and post- emergenceherbicides were tested separately. In 2001, Sarhad white variety of maize wasused as test variety, and planted on July 14. Primextra 500 FW, Stomp 330-E,Jinong 38 SL, Merline extra as pre-emergence and Primextra 500 FIN 2.5 and1.0 were applied as post-emergence spray. In 2002, maize variety Azam wasplanted as test crop variety. In 2002, two trials, one pre and second as post-emergence were laid out. Pre-emergence treatments were Primextra gold 720Sc, Dual gold 960 EC, Aatrax 90 WG. Atrazine 38 SC and Stomp 330 E. Post-emergence herbicides were Primextra 500 FW, Primextra gold 720 SC, Aatrax 90WG, Atrazine 38 SC, Jinong 38 SL and 2,4-D. During both the years, pre andpost-emergence herbicides reduced weed densities significantly over untreatedcontrol. Untreated control had a weed density of 189 weeds compared to 43 inthe 2,4-D treated plot during 2001. In 2002, weed densities were 72 and 189 inthe untreated and hand weeded plots in comparison with 27 and 39 the weednumber in the Stomp 330-E and hand weeded plots respectively. 2,4D andJinong 38 SL did not control grasses and were therefore less effectivecompared to Primextra 500 FW, Primextra gold 720 SC, Dual gold 960 EC andstomp 33-E. Cyperus rotundus was the most tolerant to all herbicides. Dualgold 960 EC and Primextra gold 720SC were the most effective herbicidesreducing weed density and increasing maize yield. Primextra 500 FW, Primextragold 720 SC, Dual gold 960 EC and Aatrax 90 WG treated plots produced maizegrain yield of 3733, 3533, 4267 and 4000 kg ha-1, respectively compared to2333 kg ha-1 for untreated control plot. Cost/benefit ratio of most effectiveherbicides was 1 to 5, which clearly demonstrated that chemical control ofweeds in maize is a very acceptable intervention, and could be easily adoptedby the farmers.