Response of Smooth Pigweed ( Amaranthus hybridus ) Accessions from Argentina to Herbicides from Multiple Sites of Action

SCURSONI, JULIO A.; MORELLO, JUAN P.; BULACIO, NICOLÁS MONTERO; VILA-AIUB, MARTIN M.; TUESCA, DANIEL; HERRERA, DANIELA MEDINA; CRESPO J, ROBERTO J.; BALASSONE, FEDERICO; LESCANO, MARÍA C.; DEPETRIS, MARA B.

WEED TECHNOLOGY

WEED SCI SOC AMER

Lugar: Laurence, KS; Año: 2022 p. 1 - 18

0890-037X

Smooth pigweed is one of the most troublesome weeds in Argentina. The objective of this study was to evaluate the sensitivity of fifty smooth pigweed accessions to fomesafen, topramezone, glyphosate, 2,4-D, and dicamba. Accessions were collected from soybean fields in different cropping areas in Argentina. The herbicide treatments were 2,4-D (1,140 g ae ha−1), dicamba (560 g ae ha−1), fomesafen (250 g ai ha−1), topramezone (34 g ai ha−1) and glyphosate (1,080 g ae ha−1). Thirty days after application, plant survival was evaluated for each treatment. Of the smooth pigweed accessions tested, 84% and 76% were susceptible (0% survival) to 2,4-D and dicamba, respectively. More than 90% of the accessions showed high (>60%) survival to glyphosate. While none of the accessions showed total sensitivity (0% survival) to the other herbicides evaluated, 43% and 72% of the accessions showed greater than 60% survival to fomesafen and topramezone, respectively. The differences in survival among accessions confirm the existence of genetic variability in Argentinian smooth pigweed and suggest that weed management practices should be prioritized to preserve the efficacy of these commonly used herbicides.