Vol. 9, Issue 3, Part B (2025)

Aim: To study the relative performance of sequential application of different pre and post emergence herbicides on weed flora & effect of herbicides on growth, yield and Economics of Bt cotton.

Design: The experiment was laid out in randomized block design with 8 treatment combination replicated thrice.

Site and duration of study: A field experiment was conducted at Cotton Research Unit, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola during the season kharif 2023-2024.

Results: All the pre-emergence and post emergence herbicides significantly influenced the weeds compared to weedy check. At 30 DAS 3 hoeing’s and 3 hand weedings recorded lowest weed count, weed dry matter and highest weed control efficiency. The treatments T₁, T₂ and T₃ where pre-emergence herbicide diuron 80 wp was sprayed @ 1.5 kg ha^-1 significantly reduced the weed population and dry weight at 30 DAS as compared to treatments T₃, T₄ and T₆ where pyrithiobac sodium 3.15 w/w + pendimethalin 34% ready mix herbicide was used as pre-emergence spray. The diuron sprayed treatments were found significantly at par with each other. At 60 DAS more or less same trend was observed in respect of weed population and weed dry weight with lowest weed population in farmers practice and highest weed population and weed dry weight in weedy check treatments. However at 90 DAS and at harvest, T₅ treatment i.e. Pyrithiobac Sodium 3.1% w/w + Pendimethalin 34.0% (Ready mix) w/w ZC 649.25 g ha^-1 (PE) fb pyrithiobac sodium 6% EC + quizalofop ethyl 4% EC w/w MEC 125 g ha^-1 (PoE, 25-30 DAS) fb hand weeding at 50-55 DAS recorded minimum weed population, weed index and weed dry weight followed by T₂ i.e. Diuron 1.5 kg ha^-1 (PE) fb pyrithiobac sodium 6% EC + quizalofop ethyl 4% EC w/w MEC 125 g ha^-1 (PoE, 25-30 DAS) fb hand weeding at 50-55 DAS which was found significantly at par with each other and significantly superior over other treatments except farmers practice where lowest population, weed dry weight, lowest weed index and highest weed control efficiency was recorded.