First report of Vaccaria sp. from Iran exhibiting cross-resistance to acetolactate synthase inhibitors in wheat fields

The spread of weed resistance to herbicides threatens both Iranian and global agriculture. In 2019, a study was conducted to ascertain the resistance of Vaccaria spp. to conventional herbicides used in wheat fields. The study employed a completely randomized design, which included five treatments and five replications. The 25 biotypes were collected from 16 cities across five provinces through a national call. To assess the resistance of these biotypes, herbicide treatments, including iodosulfuron + mesosulfuron (Atlantis), tribenuron-methyl (Granstar), 2,4-D + MCPA (U46 Combi-Fluid), bromoxynil + MCPA (Bromicide MA), and iodosulfuron + mesosulfuron + diflufenican (Othello), were applied at the recommended dose per hectare according to the Moss and Adkins evaluation method. Subsequently, a population distribution map was created using ArcGIS Pro software, categorizing biotypes into three groups: resistant, developed resistant, and sensitive to herbicides. The results indicated that seven biotypes (28%) were resistant to Granstar herbicide, two biotypes (8%) to Atlantis herbicide, and one biotype (4%) was resistant to Othello herbicide. Additionally, three biotypes (12%) were classified in the developed resistant group for Granstar herbicide, one biotype (4%) for Atlantis herbicide, and two biotypes (8%) for Othello herbicide. Notably, based on the evaluation criteria of Adkins and Moss, all collected biotypes were sensitive to the two herbicides, U46 Cambi Floyd and Bromicid MA.