Sequential Herbicide Application for Weed Control in Sugarbeets

Preplant and postemergence applied herbicides were compared for their effect on individual weed species and on sugarbeets. A combination of cycloate plus ethofume­ sate or diethatyl plus ethofumesate provided the best broadleaf weed control with crop selectivity similar to cycloate, ethofumesate, and diethatyl alone. A split appli­ cation of desmedipham plus phenmedipham was more effective than a single application in reducing broadleaf and grass weed density. Broadleaf weed density was reduced 70 to 77 percent with postemergence or preplant applied herbicide treatments, respectively, and by 93 per­ cent when preplant and postemergence herbicides were applied sequentially. Sugarbeet injury and stand reduc­ tion increased when preplant and postemergence applied herbicides were combined as compared to sugar beet selec­ tivity when preplant and postemergence applied herbi­ cides were used separately.