Investigating Herbicide Resistance of Pigweed (Amaranthus sp.) to some Registered Herbicides in Sugar Beet Fields in Iran

In order to investigate the herbicide resistance of red root pigweed to some registered herbicides in sugar beet fields in four inmportant sugar beet plantation regions (Khorasan, Khosestan, Isfahan and West Azarbaijan), a fiels experiment was carrioud out in randomized complete block design using factorial experiment with three replications. Treatment consisted of three biotypes of pigweed including two susceptible to resistance and one suseptible to herbicide and three herbicide tratments including Pyramin, Bethanal A-M and not used herbicide as check. Due to peculiar genetics and morphological characteristics of each biotype in each region, experiment of each region was analyzed seperately. The results showed that there is no significant difference between suspected and susceptible biotypes in viewpoint of herbicides effect. Mean comparison indicated that the effect of Pyramin, Bethanal AM and control on mumber and biomass of both pigweed biotypes was the same. It was concluded that pigweed was not yet resistant to registered herbicides and inappropriate control of this weed could be probably refereed to some other factors such as quality of herbide used and incorrect decision for herbide dose, time and method of application.