The Influence of pre-and Post-Emergence Herbicides on the Growth and Grain Yield of Wheat (Triticum Aestivum L.) at Kadawa , Nigeria

The study evaluated 15 pre-and post-emergence herbicides (alone and in combination) assessed alongside a hoe weeded control (weeded at 3 and 6 weeks after sowing (WAS)) and a weedy check during 2002/03 and 2003/04 dry seasons at Kadawa in Sudan Savannah of Nigeria. The trial was laid out in a randomized complete block design and replicated four times. The result showed that Oxadiazon at 1.0kga.i/ha, propanil plus bentazon at 2.0 + 1.0kg a.i/ha and metolachlor plus prometryne at 1.25 + 1.25kg a.i/ha gave the best result and could be adopted for wheat production in Nigeria. Propanil plus 2,4-D at 2.88 + 1,60kg a.i/ha, 2,4-D at 1.5 and 2.0kg a.i/ha, mixtures of metolachlor plus terbutryne at 1.0 + 1.0 and prometryne at 1.0 + 1.0kg a.i/ha selectively suppressed weeds compared to the weedy check. Sole rates of atrazine at 1.5 and 2.0kg a.i/ha and its mixtures with metolachlor at 1.0 + 0.5, 1.33 + 0.66 and 1.66 + 0.83 kg a.i/ha gave effective weed control up to 6WAS but significantly reduced wheat grain yield. Atrazine treatments particularly at 2.0kg a.i/ha proved phytotoxic to wheat with noticeable symptoms of growth and grain yield depression comparable to the weedy check. Uncontrolled weed growth throughout the crop’s life cycle resulted in 43.72 percent mean yield loss compared to the best treatment (metolachlor plus prometryne at 1.25 + 1.25kg a.i/ha) in the trial. Keywords: Herbicides, mixtures, weed, growth characters and yield