Weed infestation is one of the main constraints. On average 20% of crop yield is lost due to pest infestation, out of which 37% reduction is caused by weed infestation. Cluster bean is a poor competitor with weeds and suffer heavily in the early growth stage due to a favorable environment for weeds to thrive. The critical period of crop weed competition in cluster beans has been identified as 20-30 DAS and the presence of weeds beyond these results in yield reductions by 47 to 92%. Weed management practices decreased the weed population and dry weight and consequently increased the weed control efficiency over the weedy check.
Poor weed management is one of the important factors for the low yield of this crop. Slow growth at the initial stages of the crop favors recurrent flushes of weeds, which compete with the crop for essentials of growth and cause a heavy reduction in its seed yield. The critical period for crop-weed competition in cluster beans has been identified as 20 to 30 days after sowing and the presence of weeds showed yield reductions by 47 to 92%. Among different weed management practices, the use of herbicides is the only choice under adverse situations. However, herbicides are costly and their availability in desired quality has a residual effect. Therefore, an integrated approach (chemical and mechanical control) makes weed management more effective and economical. Effective control of weeds through cultural practices. In the long run, pre-mixture of pendimethalin+imazethapyr @ 800 g ha-1 pre-emergence was found more effective for controlling monocot weeds as well as dicot weeds. This might be due to the broad-spectrum control of weeds because of a combination of two herbicides with different modes of action and the decreasing residual effect of pendimethalin and the prolonged residual effect of imazethapyr). Higher weed control efficiency was noted in hand weeding at 20 and 40 days after sowing in cluster bean crops. Due to controlling weeds, higher growth and yield parameters of cluster beans were probable reasons for higher seed yield in intercultering+ hand weeding treatment. The weed management schedule having low weed biomass and higher weed control efficiency would provide a favorable situation for maximization of cluster bean yield potential. Among herbicide applications of pendimethalin+imazethapyr (pre-mixed) @ 800 g ha-1 pre-emergence followed by hand weeding at 30 days after sowing recorded higher net return and B: C ratio.