37 Indian Journal of Weed Science 48(1): 37–39, 2016 Imidazolinone herbicides for weed control in greengram Simerjeet Kaur*, Tarundeep Kaur and Makhan S. Bhullar Department of Agronomy, Punjab Agricultural University, Ludhiana, Punjab 141 004 Received: 18 January 2016; Revised: 2 March 2016 ABSTRACT A field experiment to study the efficacy of imidazolinone herbicides in greengram was conducted during Kharif seasons of 2012 and 2013. Ten weed control treatments viz. imazethapyr at 50 and 70 g, premix of imazethapyr + imazamox at 60 and 70 g/ha, both applied as post-emergence at 20 days after sowing; pendimethalin 1000 g and premix of pendimethalin + imazethapyr at 800, 900, 1000 g/ha, both applied as pre-emergence, along with two hand weedings and weedy check were evaluated. Imazethapyr alone and its premixes with pendimethalin and imazamox recorded effective control of mixed weed flora and produced significantly higher greengram seed yield than weedy check. Pendimethalin alone did not control Commelina benghalensis and recorded lower seed yield. All the herbicides were safe to crop. Key words: Greengram, Herbicides, Imazethapyr, Seed yield, Weed control Greengram (Vigna radiata (L.) R. Wilczek) occupies a prominent place among major pulse crops of India and is inseparable ingredients of vegetarian diet, being one of the cheapest sources for protein. Weed infestation is one of the major constraints in greengram grown in Kharif (monsoon) season and full season competition with the weeds cause yield reduction to the extent of 25-100% (Punia et al. 2004, Malik et al. 2005). The crop needs a weed free period of first 30 days, as the crop is short stature and suffers badly if weeds are not controlled at early stages (Mirjha et al. 2013). The magnitude of loss as a result of crop-weed competition depends upon type of weed species, associated with crop, their densities and duration of competition with crops. Weed emergence in greengram begins almost with the crop emergence leading to crop-weed competition from initial stages. Trianthema portulacastrum germinates at the same time as greengram crop and completes its life-cycle within 30 days and grassy weeds like ; Dactyloctenium aegyptium and Echinochloa colona germinate with the onset of rains (Punia et al. 2013). The conventional methods of weed control (hoeing or hand weeding) are labour intensive and uneconomical and may cause damage to the crop. Chemical weed control is not common as the use of herbicides may be uneconomical due to low yield potential of greengram (Reddy 2004). The available pre- and post-emergence herbicides like pendimethalin, imazethapyr are able to check the emergence and growth of annual weeds (Chhodavadia et al. 2013). This study was done to find out the relative efficiency of imidazolinone herbicides when applied alone or as premix in greengram. MATERIALS AND METHODS The experiment was conducted at Research Farm, Department of Agronomy, Punjab Agricultural University, Ludhiana (Punjab) during Kharif 2012 and 2013. The soil of the experimental site was loamy sand with normal soil reaction (pH=7.4) and electrical conductivity (0.15 dS/m). The soil was low in organic carbon (0.30 %) and available nitrogen (261.7 kg/ha) and medium in available phosphorus (12.5 kg/ha) and potassium (169.1 kg/ha). The experiment was laid out in randomised complete block design with ten treatments including pendimethalin 1000 g/ha applied as pre-emergence, premix of imazethapyr + pendimethalin 800, 900 and 1000 g/ha applied as pre-emergence; imazethapyr 50, 70 g/ha applied at 20 days after sowing (DAS), premix of imazethapyr + imazamox 60, 70 g/ha applied at 20 DAS; two hand weedings at 20 and 40 DAS and weedy replicated thrice. The crop was sown with hand drill with seed rate of 20 kg/ha keeping 30 cm row to row spacing using cv. ‘SML 668’ during 2012 and cv. ‘PAU 911’ during 2013. The pre-emergence herbicides were applied within two days of sowing with knap sack sprayer fitted with flat fan nozzle that delivered 500 liter water/ha whereas post-emergence herbicides were sprayed using 375 l/ *Corresponding author: simer@pau.edu DOI: 10.5958/0974-8164.2016.00008.3