Twisted Whorl Syndrome or Herbicide Injury in Corn?

Last week, I observed some fields that were showing signs of Twisted Whorl Syndrome in corn. An article from Purdue does a nice job summarizing the symptoms and effects. Below are some quick points from the article:

• Often occurs when corn goes from slow development (cool temps) to rapid increase in growth (warmer temps) and/or back to cool temps. We have experienced these conditions in Central Illinois in the last two weeks.
• Symptoms = Tightly wrapped whorl, that bend over towards the ground.
• V6 = common stage where corn can develop these symptoms.
• Corn hybrids can respond differently.
• While the symptoms of Twisted Whorl Syndrome look lethal, be patient, corn leaves will unwrap themselves within 7-10 days and there is likely no yield effects.
• After corn leaves have unwrapped themselves, yellow leaves/tops may be observed. This is due to the wrapped leaves not being exposed to sunlight. The yellow leaves will disappear within a few days.

Symptoms look like Group 15 herbicides (acetochlor) and/or Group 4 (clopyralid). If products like Resicore have been sprayed on corn POST, we can’t completely rule out damage from these herbicides, however, this wrapped growth typically only occurs on smaller corn from these types of herbicides. Be sure to apply herbicides according to label and prior to cutoff restrictions, which for Resicore is 11 inches. In this case, there may be an interaction between the environment and POST Resicore application that is causing this type of growth. If anyone has seen similar symptoms on corn, please reach out to me.

Regardless, I have observed signs of recovery in corn showing this symptomology within a few days after this photo was taken.

Nielsen R (2019). Yellow Tops and Twisted Whorls in Corn. Purdue Corny News Network. https://www.agry.purdue.edu/ext/corn/news/timeless/TwistedWhorls.html Accessed June 5, 2021