Abstract

                                Competition between crop plants and weeds is probably the most important single factor limiting the yield of crops. Groundnut, due to poor competing ability, faces severe weed competition at all stages of its develop- ment resulting in ultimate yield losses of more than 50% as reported by Chaugule and Khuspe (1962), Leiderman et al. (1963), Kulkarni et al. (1963), Boswell (1966) and Mani et al. (1968). The conventional weed control practices like repeated hand weedings and other intercultural operations with country-side implements are not only laborious and costly but also ineffective as timely operations are not guaranteed. The chemical control of weeds in groundnut is gaining much importance in United States of America whereas only a few reports are available in India' till now (Singh, and Moolani, 1967). The few results achieved also have little practical application. Research during 1966 at the Regional Research Station (I. A. R. I.), Hyderabad, has resulted in identifying a promising new selective herbicide, 2,4-dichlorophenyl 4-nitrophenyl ether, popularly known under the trademark Tok E-25, containing 25% active ingredient (Anon., 1966). A thorough knowledge of the proper dose, timing of its application, effect on crop and effectiveness over cultural practices in vogue was therefore felt necessary for its popularisation. With these objectives in view, a detailed investigation was undertaken during Kharif, 1967 to evaluate the effectiveness of Tok E-25 for groundnut.

Key words :