Tracing the resistance to acetolactate synthase and synthetic auxins in little mallow (Malva parviflora L.) in wheat fields of Khuzestan province

Little mallow is a common weed in wheat fields of Khuzestan province, which is often controlled by tribenuron-methyl and 2,4-D+MCPA, from acetolactae synthase inhibitors and synthetic auxin herbicides. Recently, there have been some reports about poor control of this plant with these herbicides, especially in wheat fields of Southern Khuzestan. Therefore, due to the lack of research on the occurance of mallow resistance to the mentioned herbicides and to estimate the resistance level among the mallow populations, little mallow seeds were collected from wheat fields in southern Khuzestan and whole plant assays were carried out in the pot. Dose-response results revealed that the resistance factor (RF) based on fresh weight for resistant (R) populations to tribenuron-methyl, and 2,4-D+MCPA were 2.05-10.11 and 2.51-3.09 fold higher than susceptible (S) plant, respectively. Similarly, the resistance factor (RF) based on survival plants for resistant (R) populations to tribenuron-methyl, and 2, 4-D+MCPA were 2.14-34.93 and 1.99-2.91 fold higher than susceptible (S) plant, respectively. The E population, however, was not significantly different from S population in response to tribenuron-methyl.