Relative density of weeds and weed indices as influenced by weed control options in cotton

Abstract

Field experiments were conducted at Professor Jayashankar Telangana State Agricultural University, Rajendranagar during Kharif 2017 for the evaluation of efficacy different doses of diuron in both red and black soils. The treatment consisted of test herbicides such as, diuron 80% WP at 0.5 kg/ha, 0.75 kg/ha and 1.0 kg/ha along with registered formulation of pendimethalin 38.7% CS at 677 g/ha, intercropping with green manure crop, mechanical weeding thrice at 20, 40, 60 DAS and unweeded control. The experiment was laid out in a randomised block design replicated thrice. The weed flora of the experimental field in red soil was dominated by Cynodon dactylon, Rottboellia exaltata, Parthenium hysterophorus, Trianthema portulacastrum and Commelina benghalensis. While in case of black soil, predominant flora was Cynodon dactylon, Cyperus rotundus, Parthenium hysterophorus, Euphorbia geniculata, Tridax procumbens, Cyanotis cristata, Digera arvensis and Celosia argentia. The treatments, mechanical weeding thrice at 20, 40 and 60 DAS, polymulch treatments reduced the weed growth in both red and black soils. Among the herbicides, diuron at 1.0 kg/ha fb pyrithiobac-sodium + quizalofop-ethyl in red soil and both diuron at 1.0 kg/ha and 0.75 kg/ha along with sequential application of herbicides reduced the density of weeds. Diuron could reduce the broad-leaved weeds and grasses except itch grass. Sedges are also could not be reduced by diuron. The lower values of weed persistence index was obtained with herbicidal treatments i.e., diuron at 1.0 and 0.75 kg/ha fb pyrithiobac-sodium + quizalofop-ethyl. The crop resistance index and treatment efficiency index were superior in case of polymulch and mechanical weeding thrice at 20, 40 and 60 DAS.