Response of weed population dynamics and communities on yield: A case study using Trigonella foenum-graecum L.

Field experiments were conducted for two successive years at Agronomy Research farm, CCS Haryana Agricultural University, Haryana during 2018-19 and 2019-20 to evaluate the efficacy of herbicide-based IWM strategies and to study the response of weed population dynamics and communities on fenugreek yield. Total weed density was lower in the first year as compared to second year i.e. 80 and 88 weeds m^-2, respectively. Dicotyledon/broad-leaved weeds (84.3 and 88.1% relative density) were more prevalent than monocotyledon grassy/sedgeweeds, with relative densities of 13.7 and 11.9%, respectively during both years. Lower dry weight of weeds was recorded with two hoeing employed at 30 and 60 DAS which was statistically at par with PRE application of pendimethalin + imazethapyr (RM) at 1500 g ha⁻¹ + one hoeing at 3–4 leaf stage. Among the IWM practices evaluated in fenugreek, pendimethalin + imazethapyr at 1500 g ha⁻¹ as pre-emergence andthen one spot hand weeding at 30–35 days after sowing was effective in controlling weeds which was 87.0 and 83.7% higher, respectively in first and second year than that in unweeded control. The use of imidazolinones in combination with pendimethalin (RM) improved its efficacy in controlling the predominant weeds. We concluded that a management programme based on the combination of herbicides applied at early stages with one hoeing at 3–4 leaf stage will be effective to control the future infestations in legume crops.As a result, coupling pendimethalin and imazethapyr may result in improved weed control as well as increased fenugreek productivity and profitability.