Photosystem I Electron Diverter (HG 22) Herbicide Injury in Corn
Published: 09/08/2023
Photosystem I (PSI) electron diverter, or Group 22 herbicides, divert electrons away from Photosystem I and create singlet oxygen which rapidly degrades lipids and destroys cell membranes. PSI herbicides are considered contact herbicides as cell membrane and cell destruction occurs rapidly and destroys pathways for herbicide movement in the plant. Paraquat is the most widely used PSI herbicide in production agriculture; it can be used for burndown applications in many no-tillage crops.
Paraquat injury to corn.
Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
Paraquat injury to corn.
Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
PSI herbicides are broad spectrum and should not be applied postemergence in corn as severe injury and plant death will occur. Injury symptoms appear rapidly and can occur as quickly as 30 minutes after exposure on sunny days. Symptoms appear as water soaking initially and quickly turn to necrotic spotting at the sites of herbicide exposure. In cases of herbicide drift, the symptoms will appear as necrotic spotting where the off-target droplets landed on the corn plant. Necrotic spotting will be more severe closer to the site of application and become more sporadic as you move away from the intended site of application. Injury symptoms will only occur on the corn leaves that were unfurled from the whorl at the time of exposure. Depending on the rate of exposure and corn growth stage, corn plants generally recover from exposure events to PSI herbicides.
See the Herbicide Classification Chart from Take Action for herbicide selection information to help slow the development of resistant weeds.
Prepared and reviewed by Dr. Thomas (Tommy) Butts, University of Arkansas; Dr. Joe Ikley, North Dakota State University; the Integrated Pest Management Program at Iowa State University; Dr. Sarah Lancaster, Kansas State University; Dr. Travis Legleiter, University of Kentucky; and Dr. Rodrigo Werle, University of Wisconsin-Madison.
Paraquat injury to corn. By Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
Paraquat injury to corn. By Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
Paraquat injury to corn. By Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
Gallery images courtesy Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
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