HERBICIDE EFFICACY IN WEED MANAGEMENT OF TOBACCO SEED BEDS

Abstract

Weed infested nursery beds results in severe loss of transplants and may host vectors when transplanted result in stunted growth and loss of yield. In general, hand weeding is widely followed in tobacco seed beds which needs more human labour. As labour scarcity is a major concern use of herbicides along with hand weeding was studied to see their effect on tobacco seed germination, in controlling weeds and production of transplantable seedlings. In the first year experiment Pendimethalin, Alachlor, Metribuzin and Oxyfluorfen was tried as pre plant incorporation herbicides. As the germination was affected with doses tried in the first experiment, lower doses were tried in the second year experiment excluding Oxyfluorfen replacing with post emergence herbicide quizalofop-ethyl. The treatments were pre-plant incorporation of Metribuzin @263 g a.i./ ha, @ 394 g a.i./ha, @ 525 g a.i./ha, Alachlor @ 1000 g a.i./ha, 1500 g a.i./ha and 2000 g a.i./ha, Pendimethalin @500 g a.i./ha, 750 g a.i./ ha and 1000 g a.i./ha, post-emergence application of quizalofop-ethyl @ 60 g ai/ha and hand weeding. The pre-plant incorporation (PPI) of herbicides effectively controlled the weeds upto 25 days after sowing as higher dry weight of weeds were observed from hand weeded plots. Pendimethalin and oxyfluorfen had adverse effect on tobacco seed germination. It caused poor and delayed germination. Significantly higher germination count and transplantable seedlings were observed in hand weeding plots followed by post emergence application of quizalofop- ethyl. PPI of herbicides Alachlor @1000 and 1500, Metribuzin at 263 and 394 g ai /ha doses controlled the weeds effectively and gave optimum no.of seedlings compared to other doses at 5 days before sowing.