100% RDH, Pre-emergence, Post-emergence, Sequential herbicide, Soybean residue 

Effect of time, dosage of herbicide and crop residue were evaluated in Dharwad (Karnataka) on weed flora in wheat during winter (Rabi) season of 2020-21 and 2021-22.  The experiment used a factorial randomized block design with twelve treatments, including a randomized complete block design to compare controls with treatment combinations. Results revealed that pre-emergence of pendimethalin reduced the number of grasses (3.0/m2), sedges (1.7/m2), broad-leaved weeds (4.5/m2) and total number of weeds (9.2/m2) at 20 DAS. At 40 and 60 DAS, sequential application of pre-emergence followed by post-emergence reduced the grasses (2.9 and 5.9/m2), sedges (1.1 and 1.5/m2), broad-leaved weeds (3.1 and 3.5/m2), total number of weeds (6.8 and 10.6/m2) and dry weight of weeds (1.9 and 3.4 g/m2). Among the dosage, 100% recommended dose of herbicide (RDH) recorded lower grasses, sedges, broad-leaved weeds and dry weight of weeds compared to 75% RDH. Weed population did not differ significantly with application of soybean residue and no residue treatment. Pre-emergence followed by post-emergence at 100% RDH with soybean residue recorded higher grain yield (4.17 t/ha), weed control efficiency (79.7, 92.1 and 84.5%) and lower weed index (4.5%) compared to rest of the treatments. Lower grain yield (2.98 t/ha) and weed control efficiency (65.9, 56.6 and 42.7%) were with pre-emergence at 75% RDH without soybean residue. The results suggested that pre-emergence followed by post-emergence with 100% RDH with soybean residue was the best broad spectrum effective herbicide in order to minimize the diverse weed flora in wheat.