It is a good time to remember that not all plant injuries are caused by pathogens like viruses, bacteria, or fungi. Some symptoms are caused by abiotic (non-living or environmental) factors, including herbicides.
Herbicide damage can be challenging to diagnose because many of the symptoms may look like those caused by biotic factors (pathogens). Symptoms are varied and depend on several factors, including the type and amount of herbicide, source (spray, soil, grass clipping, hay, compost), location of the symptoms on the plant, and more.
The Iowa State Plant and Insect Diagnostic Clinic does NOT test for herbicide residue in plants; we can, however, help you investigate if a pathogen is causing the symptoms.
For more information on identifying, preventing, and managing herbicide damage, check out this encyclopedia article: Understanding and preventing herbicide injury.
Other resources:
- Chemical Injury in Vegetables
- Preventing Herbicide Injury in the Landscape
- Biotic vs. Abiotic - Distinguishing Disease Problems
Lina Rodriguez Salamanca Extension Plant Pathologist and Diagnostician
Dr. Lina Rodriguez-Salamanca is a diagnostician and extension plant pathologist with the Iowa State University Plant and Insect Diagnostic Clinic (clinic.ipm.iastate.edu), a member of the National Plant Diagnostic Network (NPDN, ...
Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Horticulture and Home Pest News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on June 17, 2022. The information contained within may not be the most current and accurate depending on when it is accessed.