An Evaluation of the Efficacy of Four Wheat Selective Herbicides in the Control of Annual Dicotyledonous Weeds

The efficacy of 2,4-d, 2,4-d+mcpa, bromoxynil, tribenuron methyl in the control of 17 annual broad-leaf weed species was evaluated in five herbicide trials, each lasting two years during 2002 and 2003, in five iranian provinces: tehran, khuzestan, semnan, kermanshah and khorasan. the herbicides were applied when the target weeds were at the 2-4 leaf stage. results indicated that most target species were significantly controlled at least by one of these herbicides. however, rumex crispus, r. dentatus, fumaria officinalis and polygonum aviculare were relatively tolerant to all the herbicides. among the weed species, three of them including sinapis arvensis, rapistrum mgosum, betae maritima, were controlled completely by all herbicides. in controlling centaura depressa, chenopodium album, cephalaria syriaca, carthamus oxyacantha and sisymbrium officinalis, 2,4-d and 2,4-d+mcpa were significantly more effective than tribenuron methyl or bromoxynil. whereas, in the control of goldbachia laevigata, bromoxynil was more effective than the other herbicides. stellaria media was more sensitive to tribenuron methyl than to the other herbicides.