Recent Discovery of Amaranthus palmeri S. Watson in Italy: Characterization of ALS-Resistant Populations and Sensitivity to Alternative Herbicides

Amaranthus palmeri S. Watson (Amaranthaceae Juss.) is a dioecious noxious weed, native to the Americas, which infests summer crops. It causes high crop losses, and rapidly evolves resistance herbicides. In Europe, A. was recorded mostly as casual alien, but in 2018 it reported infesting soybean field Italy, next year two more populations were found same area. Experiments conducted on these three evaluate ALS-inhibiting herbicides, determine main mechanisms involved assess efficacy of alternative herbicides with different sites action than ALS. The confirmed cross-resistant (thifensulfuron-methyl imazamox). Gene sequencing identified Trp Leu substitution at position 574 ALS gene resistant plants, proving that mechanism for target-site related. presence other cannot be excluded. Metobromuron, metribuzin glyphosate are still effective populations.