Weed control in Bt (Bacillus thuringiensis) cotton with pre mix of pyrithiobac sodium plus quizalofop ethyl in north-west India
2019
Kaur, Tarundeep | Bhullar, Makhan S. | Kaur, Simerjeet
Cotton is the most important cash crop in North-west India. It is highly sensitive to weed competition during initial growth stages. Lack of selective post-emergence herbicides for broad spectrum weed control has been among major cotton production constraints in the region. Farmers had to rely on non-selective herbicides and or hand-weedings for post-emergence control of weeds. Efficacy of a new pre-mix of pyrithiobac sodium plus quizalofop ethyl for selective post-emergence weed control in cotton was evaluated in a field study conducted over two consecutive cropping seasons at Punjab Agricultural University (PAU), Ludhiana, India. Pyrithiobac sodium plus quizalofop ethyl at 100–125 g ha⁻¹ significantly reduced density and dry biomass of annual grasses and broadleaved weeds in both years; it gave effective control (>88%) of Trianthema portulacastrum L., Dactyloctenium aegyptium, Digitaria sanguinalis and Acrachne racemosa, fair to good control (<80%) of Digera arvensis and no control of Cyperus rotundus. Pyrithiobac sodium plus quizalofop ethyl at 125 g ha⁻¹ gave the highest seed cotton yield (2226–2367 kg ha⁻¹) which was 42–45% higher than unsprayed control and equivalent to pyrithiobac sodium plus quizalofop ethyl at 100 g ha⁻¹ and weed free check in both years. The study demonstrated that pre-mix of pyrithiobac sodium plus quizalofop ethyl at 100–125 g ha⁻¹ could be a suitable option for post-emergence selective control of grass and broadleaved weeds in Bt cotton.
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