Addition of a surfactant is not recommended. Addition of dry ammonium sulfate at 8.5 to 17 pounds per 100 gallons may increase performance of Roundup when tank-mixed with residual herbicides. Roundup should be applied prior to the end of grape bloom stage to avoid injury, or with shielded sprayers or wiper equipment, but not within 14 days of harvest. For postbloom applications, the supplemental label must be in the possession of the user at the time of application. Perennial grasses and other actively growing perennial weeds can be controlled with fall Roundup applications which can be made after 100 percent natural grape leaf fall after harvest.
Efficacy depends upon absorption into mature leaves.
Managing Weeds in New York Vineyards. Control of annual and perennial emerged weeds in bearing and nonbearing vineyards. Apply 1.5-2.5 pt of Poast per acre surface sprayed. Addition of crop oil concentrate is recommended. Consult the label for appropriate rates and materials.