California Grapes: Managing Weeds in Drought Conditions
Drought conditions in grapes create unique challenges to weed control. Without rain there is little competition from annual weeds, so you may see more deep-rooted perennial weeds that are harder to control, especially field bindweed (Convolvulus arvensis).
Preemergence herbicides require approximately 1/4 to 1/2 inch of water within 3 weeks after application. If you decide to use a preemergence herbicide, you’ll need to wait for when rain is predicted or sprinkler irrigate.
If weeds are a problem now you can apply a contact herbicide. Postemergence systemic herbicides are effective too, but some weeds are resistant or tolerant; if you choose to use one, first learn about herbicide resistance.
Areas treated only with a postemergence herbicide may need light cultivation to remove weeds usually controlled with a preemergence herbicide.
For more information on preemergence and postemergence herbicides, weed susceptibility, and weed management visit the Grape Pest Management Guidelines. View the grape year-round IPM program for more information on pest monitoring and management during winter.
U.S. Wheat Associates (USW) and the National Association of Wheat Growers (NAWG) recognize that President Trump’s executive order to withdraw the United States from the Trans-Pacific Partnership (TPP) was inevitable.