Alternative control of wild oat and canary grass in wheat fields by allelopathic plant water extracts

The increasing concern about the toxicity of synthetic herbicides has boosted the search for eco-friendly and sustainable weed management practices. Allelopathic control of weeds has received great attention in recent years as a possible alternative for weed management. Here, a two-year field study was conducted to explore the herbicidal potential of sorghum water extract alone and in combination with water extracts of other allelopathic plants: eucalyptus, sesame, sunflower, tobacco and brassica, against wild oat (Avena fatua) and canary grass (Phalaris minor), two noxious weeds of wheat fields. Water extracts were applied twice 30 and 40 days after sowing. Our results show that application of sorghum and sunflower extracts at 12 L ha^-1 each was more effective than other combinations. This treatment reduced wild oat dry matter by 42-62%, and canary grass by 36-55%. Application of sorghum and sunflower at 6 L ha^-1 each increased the wheat grain yield by 89% during the first year, and by 35% during the second year. Application of the synthetic herbicide isoproturon at 1000 g active ingredient ha^-1 was more effective for weed inhibition and yield increase than allelopathic water extracts. Nevertheless, application of sorghum and sunflower at 6 L ha ^-1 was economically more viable than the other treatments, with the highest marginal rate of return of 2824%.