Weed Management with Pro-Herbicides Benzobicylon and Florpyrauxifen-Benzyl in Louisiana Rice Production

Field studies were conducted in 2020 and 2021 to evaluate benzobicyclon tolerance to 71 weedy rice accessions collected from Louisiana and southern Arkansas. Benzobicyclon was applied at 373 g ai ha-1 as a postflood application on 3- to 4-leaf rice. At 28 DAT, less than 15% control was observed on 70% of the accessions and 80% or better control was observed on 3% of accessions. Inconsistent weedy rice control can be attributed to the presence or absence of a functional HIS1 allele. The functional HIS1 allele was present in 96% of accessions when treated with benzobicyclon control was less than 15% and 84% of these accessions possessed the ALSS653N trait signifying resistance to imidazolinone herbicides. These data indicate that the functional trait marker discovered in this study is a strong indicator of benzobicyclon weedy rice sensitivity for weedy rice accessions. Field studies were conducted in 2020 and 2021 to evaluate the activity of florpyrauxifen-benzyl and halosulfuron plus prosulfuron on aquatic weeds. Florpyrauxifen-benzyl was applied at 0, 7.3, 14.6, and 29.2 g ai ha-1 alone and in combination with halosulfuron plus prosulfuron at 55 and 83 g ai ha-1 as a surface-coated urea or foliar liquid spray application. Applications were made across four, 30 by 30-cm plastic rings, each ring contained either ducksalad, floating primrose-willow, grassy arrowhead, or pickerelweed. Ducksalad treated with florpyrauxifen-benzyl, regardless of rate or application method, was controlled 98 to 99%. Floating primrose-willow treated with florpyrauxifen-benzyl was controlled less than 50% regardless of rate or application method. Grassy arrowhead and pickerelweed treated as a foliar liquid spray application, regardless of herbicide evaluated, were controlled 94 to 99% at 42 DAT. Field studies were conducted in 2020 and 2021 to evaluate the residual activity of florpyrauxifen-benzyl applied postflood into a weed-free environment as a surface-coated urea or postflood liquid spray application. Florpyrauxifen-benzyl was applied at 0, 7.3, 14.6, 21.9, and 29.2 g ai ha-1 as a surface-coated urea or postflood liquid spray application into 53-cm diameter plastic rings. Herbicide surface-coated urea applications reduced emergence, petiolate leaf development, and flowering of ducksalad compared with postflood liquid spray applications of florpyrauxifen-benzyl