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East-Central and Southeast Iowa Crop Information

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June 22, 2020

TWISTED CORN AND YELLOW "FLAG LEAVES"

 

Many of the recent calls and field visits have related to corn that is twisted up, and often "floppy" and/or many corn plants displaying a yellow upper leaf. There are three potential causes for this. Mark Licht discusses them at https://crops.extension.iastate.edu/blog/mark-licht/twisted-whorls-buggy-whipping-yellow-leaves. Mark's emphasis is on a phenomenon commonly called "rapid growth syndrome," although it is known by other names, which Mark mentions.

In the last sentence of the first paragraph, Mark states, "Growth regulator and acetamide herbicides can also be the culprit."

 

Growth regulator herbicides include:

Acetamide herbicides include

I have been in several fields with twisted corn where Resicore was applied. The active ingredients in Resicore are:

  So in those fields, is the twisting due to

The answer is, "Who knows?"

The good news is that the vast, vast, vast majority of the plants will "break out" of the twisting without consequences, regardless of the cause. The yellow top leaf is one that just "broke out" and has not yet had much chance to conduct photosynthesis. An inspection of lower leaves on the plants will reveal that they are wrinkled, especially along the leaf margins, from the prior twisting. If a stake is placed by such a plant and then the plant is re-visited in a few days, the leaves will all be green.

 

REMINDER

Remember that the on-line field day for the Southeast Research and Demonstration Farm begins Tuesday at 8:00 a.m. Although there is no fee, registration is required and you will then be sent the link to join. You may participate in part or all field day webinars. Certified Crop Advisor CEUs will be available for the last three sessions. To see more information, see the Calendar Items following.

 

CALENDAR ITEMS

 

Spring Field Day - Southeast Research and Demonstration Farm

8:00 - 8:30 a.m., Tuesday through Friday, June 23 - 26, 2020 (a different topic each day)

On-line

Details, including required registration, are at: https://www.extension.iastate.edu/Pages/eccrops/meetserc.html.

 

Spring Training for Certified Crop Advisors

8:00 a.m., Wednesday, July 1, 2020

On-line

Details, including required registration and $25.00 fee payment, are at: https://www.extension.iastate.edu/Pages/eccrops/meetserc.html.

 

 

If you have any questions, please feel free to contact the Iowa State University Extension Office.
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Last Update: June 22, 2020
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