Herbicide injury symptoms can sometimes be confused with injury resulting from viruses or deficiency of plant nutrients. Most herbicides affect affect the new growth of grapevines, causing deformation of both shoots and leaves. The symptoms tend to disappear later in the season as the malformed foliage is covered up by new growth. Serious crop damage can result if contamination occurs during the early portion of the growing season.
Common herbicides resulting in drift and damage to grapevines include:
2,4-D, dicamba, triclopry and other phenoxy herbicides; glyphosate
See the Field Guide for Integrated Pest Management in Pacific Northwest Vineyards (PNW644) for pictorial guides to determining damage caused by various herbicides.
Many agricultural analytical labs can also test for potential herbicide residue. To see a list of potential testing laboratories, visit: https://wine.wsu.edu/extension/pest-management/