resistance of wild mustard (sinapis arvensis) and turnipweed (rapistrum rugosum) to tribenuron-methyl herbicide in aq qala

over the past 20 years since tribenuron-methyl herbicide registration in iran, reports of erratic control of broadleaf weeds with it have increased in wheat fields of aq qala. in order to evaluate the incidence of resistance in wild mustard (sinapis arvensis) and turnipweed (rapistrum rugosum) to tribenuron-methyl herbicide, dose-response assays were conducted during the years 1390 and 1391 at gorgan university of agricultural science and natural resources. wild mustard and turnipweed biotypes with suspected resistance to tribenuron-methyl herbicide were collected from wheat fields by moving on two hypothetical diameter of aq qala map. for each weed species, one susceptible biotype also collected from areas which had never been applied by herbicides. in these experiments, responses of sensitive and suspected resistance biotypes of both weeds were assayed by spraying the seedlings with different doses of tribenuron-methyl herbicide. dose-response assays indicated resistance of wild mustard and turnipweed to tribenuron-methyl herbicide. resistance factors of sra2 biotype of wild mustard and srr1 and srr2 biotypes of turnipweed to tribenuron-methyl herbicide were 4.05, 26.90 and 24.42, respectively. this is first report of resistance in wild mustard and turnipweed to tribenuron-methyl herbicides in the country. distribution maps of infected fields to resistant wild mustard and turnipweed biotypes were processed using geographic information system. results of this study could be used for running programs to manage resistant weeds and to prevent the development of resistant biotypes to other parts of the region.