Efficacy of herbicides on weed management and productivity of castor (Ricinus communis L.)

Weed competition is a major limiting factor in castor (Ricinus communis L.) cultivation, which is significantly reducing growth, yield and economic returns of the crops. A two-year field experiment (2022-23 and 2023-24) was conducted at the College of Agriculture, Anand Agricultural University, Vaso, Gujarat to evaluate the efficacy of various herbicidal and integrated weed management strategies on weed suppression, growth and seed yield of castor. The field study comprised ten treatments involving pre-emergence (PE) and post-emergence (PoE) herbicides, sequential applications and manual weeding operations arranged in a randomized block design with three replications. Results revealed that IC fb HW at 20, 40 and 60 DAS (T9) was the most effective treatment achieving the complete control of both monocot and dicot weeds at 25 DAS and maintaining the lowest weed density (2.45 and 2.47/m²) with corresponding weed dry weight of 2.45 and 2.47 g/m² at harvest with 100% weed control efficiency (WCE) at 25 DAS and 83.84% at harvest. This treatment also produced the tallest plants (163.07 and 160.67 cm), higher spikes per plant (8.38 and 7.97) and superior seed yields of 3154 and 2917 kg/ha across the two years, respectively. Among herbicide treatments, pendimethalin 30% EC 1000 g a.i./ha PE fb IC + HW at 40 DAS (T2) and oxyfluorfen 23.5% EC PE fb IC + HW at 40 DAS (T3) effectively suppressed weeds and produced seed yields at par with IC fb HW at 20, 40 and 60 DAS (T9). The highest weed density and dry weight along with the lowest seed yields (1945 and 1659 kg/ha) both years were recorded under the weedy check (T10).