Tolerance of azuki bean to herbicides applied preplant for weed control in a strip‐tillage cropping system

Abstract

AbstractFive field experiments were conducted at Huron Research Station near Exeter, Ontario, Canada, during 2018 to 2020 to assess the tolerance of strip‐till‐grown azuki bean to various preplant (PP) herbicides. The herbicides selected have activity on glyphosate‐resistant (GR) Canada fleabane, an emerging weed biotype in strip‐till azuki bean production. Saflufenacil, metribuzin, 2,4‐D ester, saflufenacil + metribuzin, saflufenacil + 2,4‐D ester, metribuzin + 2,4‐D ester, and saflufenacil + metribuzin + 2,4‐D ester, applied PP 1 week before seeding, at the proposed label rate (1X) and twice that rate (2X) caused as much as 6%, 5%, 6%, 7%, 8%, 10%, and 13% visible azuki bean injury. The herbicide‐induced azuki bean injury was transient and had no effect on plant density, aboveground dry biomass, height, maturity, and yield except for the dry biomass which was reduced by 28% with metribuzin + 2,4‐D ester and 36% with saflufenacil + metribuzin + 2,4‐D ester at the 2X rate and azuki bean height which was reduced 9% at the 2X rate with saflufenacil + metribuzin + 2,4‐D ester. Based on these results, saflufenacil, metribuzin, 2,4‐D ester, saflufenacil + metribuzin, saflufenacil + 2,4‐D ester, and metribuzin + 2,4‐D ester applied PP have potential for GR Canada fleabane control in strip‐till azuki beans. However, there is not enough crop safety for using a three‐way tankmix of saflufenacil + metribuzin + 2,4‐D ester, applied PP, in azuki bean production.