Hydrangea: Herbicide damage

Biology

Symptoms of herbicide damage may be confused with damage from insects, disease, or cultural problems. Specific injury symptoms vary depending on degree of exposure, product used, and plant species. Damage may not appear immediately, and plants may exhibit symptoms for more than one growing season. In addition to uptake by roots and leaves, herbicides may also cause damage when they contact thin or green bark, even if they are not applied directly to the plant. Some common symptoms of herbicide injury include upward or downward cupping of leaves, as well as elongation, stunting, twisting, narrowing or distortion of leaves and shoots. Leaves may turn yellow, either between the veins, along the veins, or along the leaf margins. Products containing glyphosate may cause chlorosis, stunting, distortion, and death beginning with the youngest tissues. Again, however, the symptoms vary greatly depending on the amount of exposure. Soil-applied herbicides such as dichlobenil (Casoron) or long-term residual products may cause symptoms of inhibited root growth such as yellowing of leaves or leaf veins, leaf tip necrosis, and marginal leaf necrosis. For more information on specific herbicides, see the Herbicide Damage section of this website. Tips on pesticide use and preventing plant damage can be found at the “More information on using pesticides” link below.

Management Options

Use Integrated Pest Management (IPM) for successful plant problem management.

Non-chemical Management

Select non-chemical management options as your first choice!

• Use care when applying herbicides near desirable plants. When practical, use separate spray equipment for herbicides and fungicides/insecticides to avoid accidental damage.
• Herbicides may cause damage when they contact thin or green bark, even if they are not applied directly to a plant or its leaves.
• Do not apply herbicides when drift onto nearby desirable plants is likely.
• Use caution when using soil-applied products to keep contaminated water away from root zones of susceptible ornamentals.
• Use special care when applying herbicides to turf areas near ornamental plantings.
• Maintaining plant health with proper watering and nutrition may help plants recover from minor damage.
• When diagnosing chemical injury, first eliminate possible insect, disease, and cultural problems which may cause similar symptoms.

Chemical Management

IMPORTANT: Visit Home and Garden Fact Sheets for more information on using pesticides.

• None recommended