University of Illinois Extension
University of Illinois Extension - Selecting Shrubs for Your Home
http://www.urbanext.uiuc.edu/shrubselector
Plant Growth Regulator (PGR) Herbicide Injury
Purple coneflower plant as affected by PGR herbicide drift.
Severity: Can vary out of 5
Frequency: out of 5
Symptoms:

The growth regulator compounds mimic different growth regulating compounds in the plant and may cause a variety of growth abnormalities in susceptible species. The injury symptoms generally are first seen in the newly developing tissue or leaves.

Benzoic Acids: dicamba (Banvel, Clarity, and a component of Marksman and Distinct)

Phenoxyacetic acids: 2,4-D, 2,4-DB, MCPP, and MCPA.

Pyridinecarboxylic acids: clopyralid (Stinger, Lontrel, and a component of Curtail), fluroxypyr (Starane, Spotlight, and Vista), picloram (Tordon) and triclopyr (Garlon and Turflon Ester).

Characteristics of activity:

  • Translocated in both xylem and phloem.

Symptoms of Injury:

  • Stunting and cupped-shaped crinkled leaves.
  • Twisting of stems and petioles.
  • Leaf strapping,puckering, parallel venation. (associated with pyridinecarboxylic acids).
Cycle:
Management:
  • Read and follow all label directions.
  • Use caution when applying PGR herbicides around broadleaf plants as desirable plants may be sensitive and injury may result.
  • Do not spray when air temperature and/or humidity is high or is expected to be high.
  • Do not spray when wind speed and direction are such that herbicide drift is likely to occur.
  • Affected plants may or may not survive herbicide drift; it depends on both the degree of exposure and the plant's tolerance to the herbicide.
  • Water and fertilize plants as needed to promote good plant health.
  • Illinois residents: If you suspect herbicide injury as a result of off-target movement from a nearby application and you are interested in filing a complaint with the Illinois Department of Agriculture, call the Illinois Department of Agriculture's Bureau of Environmental Programs at 1-800-641-3934. To learn more about spray drift and the formal complaint process, visit the Illinois Pesticide Safety Education Spray Drift Resources website.
  • Non-Illinois residents: If you are interested in filing a complaint, contact your state pesticide control official via the Association of American Pesticide Control Officials website.
Associated shrubs: