Efficacy of isoproturon with and without surfactant on weed suppression in wheat (Triticum aestivum)

A field experiment was conducted during the winter seasons of 1999-2000 and 2000-2001 to study the effi- cacy of lsoproturon with and without surfactant on weed suppression in wheat (Triticurn aestiburn L. emend. Fiori & Paol.) at Pusa, Bihar. Tank mixing of wet we1 2% to isoproturon @ 1.0 kgtha as post-emergence was as effec- tive as manual weeding, produced lower weed dry weight and higher number of effective tillerstm row length, grainstspike and 1,000- grain weight and hence significantly higher grain yield. Reduced dose of lsoproturon @ 0.75 kgtha with different surfactants used was also effective in reducing the weed population and their dry weight and in increasing the yield attributes and grain yield significantly over the control. lsoproturon without surfactant was least effective in controlling weeds and had minimum impact on enhancing seed yield compared to lsoproturon with surfactant. Maximum net returns were obtained from weed-free plot, while benefit: cost ratio was maximum with isoproturon @ 0.5 kgtha with T. pal 2%.