Weeds do enormous damage to the wheat crop. They directly deplete the soil nutrients and moisture and compete with crop plants for light and space thus, reduce the crop yields. Indirectly, they cause damage to the crops harbouring pests and disease agents. Because their management involves costs therefore, reduction in the net returns make harvesting and threshing of crop costly and laborious and lower the quality and reducing the value of produce. It has been estimated that by weeds losses cause ranging from 10 to 40 per cent in wheat crop depending upon their intensity.
The major weeds prevalent in wheat fields are dicot and monocot weeds grown in Rabi season viz. Bathua (Chenopodium album), Gazari (Fumaria parviflora), Katili (Cersium arvensis), Krishnneel (Anagallis arvensis), Akari (Vicia hirsuta), Sengi (Melilotus alva/Meliotus indica), Chatari matari (Lathyrus aphaca), Satyanashi (Argemone maxicana) etc. Like wise monocot weeds viz., Gehusa/Gullidanda / Gehun ka mama (Phalaris minor), wild oats (Avena fatua), Piazi (Asphodelus tenuifolius) etc. impose serious problem in wheat fields. In addition to these, doob (Cynodon dectylon) is a major perennial weed.
With the introduction of dwarf wheat, two most serious weeds namely Phalaris minor and wild oats which remained inconspicuous by their absence in the tall wheat have assumed serious proportions in major wheat growing areas of India. Since both wild oats and Phalaris minor belong to the grass family and have growth habit and development similar to wheat, it is very difficult to distinguish them from wheat plants in the vegetative phase. Moreover, since these weeds with profuse tillering grow taller than the dwarf wheat, they cause partial shading of wheat plants.