Question:
How can I tell if my plant has been damaged by herbicide drift?Answer:
Symptoms of herbicide damage vary and depend on the type, formulation, concentration, mode of action, source, and amount of herbicide, as well as the plant species affected, application method, equipment used, and weather conditions during and after application.
Typical Herbicide Injury Symptoms
Symptoms of herbicide injury are varied but, in general, include:
- Distorted, twisted, or irregular stem growth (especially at growing points)
- Cupping or curling of leaves
- Deformed, twisted, and/or irregular leaf growth
- Epinasty (bending or twisting of plant parts, especially stems, downward and outward)
- Leaf veins develop a parallel orientation instead of a typical net venation pattern
- Petiole twisting
- Thickening or callusing of stems
- Blotches or spots in a droplet or spray pattern
- Yellowing of leaves and/or stems
- Die-back of leaves and/or stems
- Reduced vigor or growth rate
- Weak emergence and seedling establishment
- Delayed or uneven flowering and fruiting
- Plant death
Other Factors to Identify Herbicide Injury
Pattern of Symptoms
Herbicide injury typically affects all or most plants in an area, regardless of species. For example, distorted, weak growth with leaf yellowing is observed on tomatoes, beans, broccoli, and peppers in the same garden area. Or tomatoes, peppers, and beans at one end of the garden all show symptoms, and the same species at the other end (further from the herbicide application) do not.
Depending on the active ingredient, symptoms may only be on certain types of plants. For example, all the broadleaf plants in the area show symptoms, but none of the grassy plants have issues. While herbicide damage can cause similar symptoms across multiple species in the same area, insect or disease issues rarely affect unrelated plant species in the same way.
Sensitivity
Some plant species are more sensitive to certain types or formulations of herbicides than others. For example, plants like tomato, grape, pepper, apple, maple, peach, strawberry, elm, redbud, geranium, petunia, and coleus show much more sensitivity to off-target applications of 2,4-D or Dicamba than plants like hosta, daylily, zinnia, marigold, and vinca.
Sensitive species will show more extensive damage than non-sensitive species. More sensitive plant species are also more likely to show damage at greater distances from the herbicide application than less sensitive species.
Time for Symptoms to Appear
Herbicide injury symptoms may develop within a few hours, a few days, or more than a week after the application, depending on the product used.
Herbicide residue or carryover in mulch, manure, compost, and soil can cause injury symptoms in the days or weeks following the application of the soil or amendment.
Knowledge of Nearby Applications
If you know a herbicide application was made in the area prior to the appearance of symptoms, that can further confirm herbicide injury as the cause of the issues. Remember, just because a herbicide was applied nearby does not mean the symptoms observed are caused by herbicide drift or misapplication. But when symptoms or patterns indicate herbicide injury, and it's known that an application was made nearby, it can help further confirm the cause of the issue.
Follow-up Questions
What can I do if my plants have been damaged by herbicide drift?
Can I eat fruits and vegetables that have been damaged by herbicides?
Learn more in this article: Herbicide Injury to Garden Plants.