Effect of weedicides on weeds and yield of Bt cotton (Gossypium hirsutum L.)

Abstract

A field trial was conducted at Cotton Research Station, Nanded (M.S., India) to evaluate effect of pre and post emergence weedicides in Bt cotton during 2012-13 to 2014-15 under rainfed condition for three years in kharif season. The experiment was conducted with eight treatments laid out randomized block design in three replications. Weedicides viz., PE (Pendimethalin), PoE (Quizalofop ethyl, Pyrithiobac sodium and Glyphosate) were evaluated alone or in combination along with weed free check and un weeded control. The research results revealed that the seed cotton yield was reduced by 60.07 per cent due to weeds when were not controlled. The non-selective weedicide Glyphosate 41 SL @ 1.0 kg a.i. ha-1 as directed spray at 45 DAS recorded lowest weed density and weed dry weight at 9 WAS and at harvest. Among the selective weedicides, tank mix application of Pyrithiobac sodium 10 EC @ 62.5 g a.i. ha-1 + Quizalofop ethyl 5 EC @ 50 g a.i. ha-1 fb one hoeing at 45 DAS treatment was found to lower weed density and dry weight of grassy as well as broadleaf weeds. The seed cotton yield from treatments Glyphosate (1572 Kg ha-1) and tank mix Pyrithiobac sodium + Quizalofop ethyl fb one hoeing (1570 Kg ha-1) were on par with weed free check (1698 Kg ha-1).