An investigation entitled “Chemical weed control in chilli + onion intercropping system” was carried out at the Vegetable Division in Kittur Rani Channamma College of Horticulture, Arabhavi, University of Horticultural Sciences, Bagalkot (Karnataka) during Kharif season of 2014 and 2015 on well drained red loamy soil to find out the suitable approach (herbicides+cultural practices) for weed management and for improving the productivity of chilli+onion intercropping system. Observations on weed control treatments showed marked difference among weed, growth and yield parameters in chilli and onion. Among the different chemical treatments, pre-emergent application of alachlor @ kg ai/ha + 2 HW at 45 and 60 DAT (T4) recorded the lowest pooled dry matter of weeds ( g), lowest population of monocot () and dicot weeds () and thus exhibited the highest weed control efficiency (). Unweeded check recorded highest weed population () and weed dry weight ( g). Significantly higher yield per ha of green chilli( q) and onion ( q), net returns () and B:C ratio () was recorded in T4 followed by pendimethalin @ kg ai/ha + 2 HW at 45 and 60 DAT.
