Impact of Tembotrione on Weed Growth, Yield and Economics of Maize (Zea mays L.) under Mid Hill Conditions of Himachal Pradesh

To assess the impact of tembotrione on weed growth, yield and economics of maize (cv. KH 101), field trials were conducted during the kharif season of 2014 and 2015 on a silty clay loam soil at Palampur. Tembotrione 100, 125 and 150 g ha−1, each applied at 20 and 30 days after sowing (DAS) of maize, tembotrione 125 and 150 g ha−1 + surfactant applied on 20 DAS of maize, atrazine 1000 g ha−1 (pre) fb atrazine 750 g ha−1 (post) and atrazine 1000 g ha−1 + pendimethalin 1000 g ha−1 (pre) were compared to manual weeding (20, 40 and 60 DAS) and weedy check. Application of tembotrione at 125 and 150 g ha−1 with surfactant (20 DAS) and at 150 g ha−1 without surfactant (30 DAS) effectively reduced the dry weight of Echinochloa colona, Commelina benghalensis, Polygonum alatum, Ageratum conyzoides and the combined of all weeds. Tembotrione 125 and 150 g ha−1 + surfactant (20 DAS) produced significantly higher grain yield of maize followed by tembotrione 150 g ha−1 applied on 30 DAS, tembotrione 125 g ha−1 applied on 30 DAS and tembotrione 150 g ha−1 applied on 20 DAS. Grain yield of maize negatively correlated with dry weight of Echinochloa, Commelina, Polygonum, Ageratum and the combined of all weeds. With every 1 g m−2 increase in weed dry weight, the grain yield of maize reduced by 33.7 kg ha−1. The economic threshold levels with the herbicidal management practices varied between 5.1–9.3 g m−2 and that with manual weeding 46–50.8 g m−2. Tembotrione 150 g ha−1 + surfactant and tembotrione 125 g ha−1 + surfactant applied on 20 DAS and tembotrione 150 g ha−1 applied on 30 DAS gave higher weed control efficiency, crop resistance index and efficiency index and lowest weed index over other treatments. Herbicidal treatments had only 0.131–0.201 times of application cost than that under manual weeding thrice. Herbicidal treatments resulted in 9.7–13.3 times higher marginal benefit: cost ratio over hand weeding thrice. Uninterrupted growth of weeds reduced the grain yield of maize by 63.5%.