Preemergent herbicides were applied to vineyards in the southcentral Missouri Ozark region. These were applied at full label rate in the fall or in the spring, at half rate in the fall and again in the spring, and as tank-mixes in the spring. Days of acceptable annual weed control (30% or less cover) beyond the untreated control were determined for these application methods over three years. The fall applications were effective at controlling winter annual weeds and early summer annual weed growth the following season. By mid summer the fall applied preemergents lost residual activity. Splitting the label rate between fall and spring was no better than a full rate spring application at increasing the days of acceptable summer annual weed control. Single preemergent spring application performed as well as tank-mixes.
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