Abstract
During crop years 2023 and 2024 staff at Amalgamated Sugar, University of Idaho, and Oregon State University fielded several calls regarding Palmer amaranth and waterhemp in sugar beet, right-of-way, and several other crops. About 70% of the Palmer samples submitted during 2023 and 100% of the waterhemp samples submitted were confirmed glyphosate resistant. Group 15 herbicides such as acetochlor, dimethenamid-P, and S-metolachlor are very effective or Palmer amaranth and waterhemp control. However, these herbicides are only labeled to be applied when sugar beets reach the 2-leaf stage. Trials were initiated in three locations in Oregon and Idaho during 2024 to evaluate the safety of Warrant®, Dual Magnum®, and Outlook® applied preemergence on sugar beet for early season weed control. An additional factor, a seed treatment, fluxofenim, used as a safener on grain and forage sorghum seed against S-metolachlor injury, was also evaluated for efficacy on sugar beet seed.
