Herbicide Injury

Cooler and wetter than normal conditions have brought attention to the possibilities of increased herbicide damage in corn. Much of the corn planted in mid-April has emerged and started the process of metabolizing herbicides. Cool temperatures cause plant metabolism to slow, as well as slow herbicide degradation by the crop. Plant injury can occur when the right conditions exist. Symptoms of injury are highlighted below.

Photosynthesis Inhibitors

• Photosystem II Inhibitors

• Atrazine and metribuzin

• Yellow leaves

• Necrotic spotting

• Older leaves most affected

Photo courtesy of Purdue Extension

Pigment Inhibitors

• HPPD Inhibitor

• Mesotrione (Callisto)

• Bleached white leaves

• Leaf yellowing

Photo courtesy of Mike Cowbrough,

(Ontario Ministry of Agriculture, Food and Rural Affairs)

Seedling Shoot Growth Inhibitor

• Long-Chain Fatty Acid Inhibitors

• S-metolachlor (Dual)

• Buggy whipped leaves

• Twisted leaves

• Poor seedling root & shoot growth

Photo courtesy of Missouri Extension

Crops will generally outgrow the injury as long as symptoms are not so extensive to kill the plant and yield is generally unaffected. Herbicide injury can mimic other deficiencies and symptoms. If you need help identifying a symptom, please feel free to contact us here at Frontline Genetics and we will be happy to help in any way that we can.