Weed Control Introduction Weed infestation in groundnut is one of the main factors for loss in yields to the tune of 13.80 per cent. Erect and bunch types suffer more than spreading types. Similarly, kharif groundnut is affected more than rabi summer groundnut. The weed competition at early stage of groundnut is maximum because of initial slow growth but it is relatively low at the end of expansion of phenophases where complete ground cover is attained by groundnut canopy. The critical period of crop-weed competition was reported to be between 28 and 45 days after sowing. The major weeds generally found in groundnut fields are: Cynodon dactylon, Echinochloa colonum, Dactyloctenium degyptium, Digitaria sanguinalis, Sorghum halpense, Echinochloa crusgalli (among monocots) and Amaranthus viridis, Celosia argentea, Euphorbia hirta, Tridex procumbens, Abutilon indicum, Phylanthus niruri and Chenopodium album (among dicots). The secretions of roots of the weeds like Cirsium arvense, Abutilon indicum, Chenopodium album etc., could be a serious impediment in the early establishment of groundnut and thereby, could limit the absolute realisation of groundnut yields if not controlled timely. Cultural method of weed control is a common practice in groundnut. Generally, one hand weeding at 30 days after sowing (DAS) or two weedings at 15 DAS and 35 DAS control(s) weed. But it is time consuming, expensive and tedious. Herbicides found effective against weeds and tested in all parts of the country are given below: Name Doses Mode of application Remarks Alachlor 1.5 kg/ha Pre-emergence (shallow incorporation i.e., 5 cm if no rain within one week after application Controls mostly monocots Nitrofen 1.5 kg/ha Pre-emergence (apply just after sowing) Controls mostly monocots Fluchloralin 1.5 kg/ha Pre-plant incorporation (5 cm deep immediately after application) Controls both monocots and dicots Trifluralin 1.5 kg/ha Pre-plant incorporation (apply one day prior to sowing) Controls both monocots and dicots Pendimethalin 1.0 kg/ha Pre-emergence (apply within 24 hours) Mostly grassy weeds Dual 1.5 kg/ha Post-emergence (apply at 20-25 DAS Mostly grassy weeds Fluzy-flop-p Butyl 0.5 kg/ha Post emergence (apply at 20-25 DAS) Mostly grassy weeds Use of proper doses of these herbicides generally does not hamper nodulation in groundnut. But continuous use of herbicides might result in soil and ground water pollution in long run. The integrated weed management thus offers a suitable alternative. When the above herbicides are combined with one or two hand weedings at 30 and 45 DAS controlled weeds efficiently and recorded higher pod yield of groundnut.

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