Mostly affects broadleaf plants; however, some grassy plants can also show injury.

Symptoms

These herbicides inhibit key enzymes in various amino acid synthesis pathways.

• Imidazolinones: imazaquin (Scepter, Image), imazapic (Plateau), imazapyr (Arsenal, Chopper), imazethapyr (Pursuit), imazamox (Raptor).
• Sulfonylureas: chlorimuron (Classic), primisulfuron (Beacon), thifensulfuron (Harmony GT), nicosulfuron (Accent), halosulfuron (Permit, Sedgehammer), and tribenuron (Express).
• Triazolopyrimidine sulfonanilides: flumetsulam (Python) and cloransulam (First Rate)

Characteristics of activity

• Translocation in both xylem and phloem.

Symptoms of injury

• Stunted plants.
• Leaf yellowing or chlorosis of leaf margins, purpling of new leaves first.
• Slow plant death.
• Early symptoms may appear similar to potassium deficiency.  

Management

• Read and follow all label directions.
• Use caution when applying herbicides around plants as desirable plants may be sensitive and injury may result.
• Do not spray during cool, wet weather as herbicide is metabolized slower at these times.
• 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 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 Resource.