Abstract
Parthenium hysterophorus L. (parthenium weed) is a destructive invasive weed in agroecosystems of >45 countries. Chemical control is highly effective and economical against parthenium among various weed control strategies. This two-year field study was carried out to evaluate the effectiveness of five herbicides applied 25 days after parthenium emergence viz., atrazine 80WDG at 360 g a.i. ha-1 , atrazine + S-metolachlor 720SC (320:400) at 720 g a.i. ha-1 , bromoxynil + MCPA + metribuzin 720EW (20:20:7) at 470 g a.i. ha-1 , atrazine + nicosulfuron 22SC (2.5:19.5) at 385 g a.i. ha-1 and dicamba 40.6AS at 304.5 g a.i. ha-1 . Application of bromoxynil + MCPA + metribuzin provided 100% control. Dicamba was the second most effective herbicide with the lowest parthenium dry weight (2.9 to 9.7 g m-2 ) and its uptake of N (1.5 to 4.5 kg ha-1 ), P (0.16 to 0.66 kg ha-1 ) and K (1.0 to 3.9 kg ha-1 ). Herbicide applications increased maize grain yield by 23 to 138%. Bromoxynil + MCPA + metribuzin at 470 g a.i. ha-1 showed superlative performance by achieving the highest grain yield (9.51 t ha-1 ). This herbicidal mixture was proved to be the most efficient and economical for parthenium control as it exhibited the highest marginal rate of return (706 to 750%). It is recommended that Bromoxynil + MCPA + metribuzin at 470 g a.i. ha-1 should be used for controlling parthenium in maize crop.
