Glufosinate Rates, Timings, and Additives for Weed Control in Glufosinate-Resistant Sugarbeet

Abstract

Two experiments were conducted to evaluate weed control with glufosinate in glufosinate-resistant sugarbeet. The first experiment evaluated glufosinate rate, application timing, and combinations with ammonium sulfate (AMS). The second experiment examined glufosinate alone and in combination with postemergence (POST) or preplant incorporated (PPI) ethofumesate. In the first experiment in 1998, increasing glufosinate rate improved common lambsquarters ~ � control and redroot pigweed control was greater when I � glufosinate was initially applied mid-post (MP) compared to early-post (EP). In 1999, increasing glufosinate rate, beginning treatment at the EP application timing, and the addition ofAMS, increased redroot pigweed control. Barnyardgrass control also was improved with the higher glufosinate rate and with the addition of AMS. Sugarbeet yield in 1998 was not significantly affected by glufosinate treatments. In 1999, the addition of AMS to low glufosinate rates and the addition of AMS to treatments applied beginning MP increased sugarbeet yield. In the second experiment, three applications of glufosinate and two applications of glufosinate following PPI ethofumesate resulted in weed control equal to a standard herbicide program consisting ofPPI ethofumesate followed by a premix of ethofumesate, desmedipham, and phenmedipham (1: 1: 1