ALS (HG 2) Inhibitor Herbicide Injury in Corn
Published: 09/08/2023
Acetolactate synthase (ALS) inhibitors, Group 2 herbicides, block the acetolactate synthase enzyme, preventing the formation of amino acids and protein creation within the plant.
ALS inhibitor herbicide injury can occur from application, physical drift, and carryover and is slow to develop with symptoms that may take up to two weeks to appear. Injury is more likely to occur in cool and wet weather conditions, soil with low organic matter, and shallow seeding depth. Injury also occurs when ALS-inhibiting herbicides are applied sequentially or in tank mixes with organophosphate or carbamate insecticides, including in-furrow or soil applied insecticides. Certain corn hybrids, especially popcorn and sweetcorn, can have increased sensitivity to ALS-inhibiting herbicides. ALS inhibitor herbicide symptoms include stunted growth and yellow or yellow-banded, deformed young leaves that turn a light yellow-green. Injury occurs in the newest growth of the corn plant. Stacked internodes are also a very common symptom of Group 2 injury. Affected plants may also have short lateral roots that appear similar to the bristles of a bottle brush. Symptoms occurring from applications after the V6 stage include ear deformation.
ALS herbicide injury to corn foliar tissue.
Kristine Schaefer.
ALS herbicide injury to corn ear.
Kristine Schaefer.
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.
Pyrithiobac injury to corn. By Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
Chlorsulfuron injury to corn. By Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
Penoxsulam injury to corn. By Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
Pyrithiobac injury to corn. By Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
Imazethapyr injury to corn. By Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
Metsulfuron injury to corn. By Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
Trifloxysulfuron injury to corn. By Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
Metsulfuron injury to corn. By Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
ALS herbicide injury to corn ear. By Kristine Schaefer.
ALS herbicide injury to corn leaves. By Kristine Schaefer.
Gallery images courtesy Kristine Schaefer, Iowa State University and Cal Shumway, Bob Scott, and John Boyd, www.uada.edu.
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