Herbicides used near grapevines may drift or overspray onto the vines and damage them.
Identification
Herbicide damage symptoms vary in appearance partly due to the particular herbicide, plant parts exposed, and season of exposure. Necrotic spots mostly on leaves of similar age may indicate aerial drift onto foliage of a postemergence herbicide. Chlorosis or necrosis caused by a soil-applied preemergence herbicide usually is most prominent in older foliage, where time has allowed the herbicide to accumulate. Other symptoms include leaves and shoots that are cupped or otherwise distorted and aborted flowers. For more discussion and photos see Herbicide Phytotoxicity and the Herbicide Symptoms tool.
Various other causes can produce symptoms that resemble those of herbicide phytotoxicity. These include
- aeration deficit
- leaf spot pathogens
- nutritional disorders
- pH, excessive acidity or alkalinity
- other chemical phytotoxicity
- root-feeding nematodes
- salinity
- viral diseases
- water deficit
Damage
Grapevines exposed to herbicide can be killed or severely debilitated. Grapes are especially susceptible to injury from summer and fall herbicide applications.
Solutions
Avoid or minimize herbicide injury by thoroughly reading the pesticide’s product label and following the instructions carefully. See Pesticides: Safe and Effective Use in the Home and Landscape for helpful information. Keep herbicide drift and spray off of grape foliage and shoots to avoid injury. Provide injured vines a good growing environment and appropriate cultural care so they are more likely to recover from herbicide injury.
References
Adapted from Grape Pest Management Third Edition from the University of California Agriculture and Natural Resources.
