Heads up for stalk rot

September 30, 2016 9:57 AM

Seems like I have written an article on stalk rot about every year for the last five or six seasons. Luckily, for the most part, the last few years it was a “heads up” about a relatively small amount of fields that were having lodging issues. However, this year it sure seems like stalk integrity issues are a lot more prevalent across the state than they have been in years.

stalk rot in corn fieldThe short version is this: Yes, we have to get these beans out while the getting is good, but when we get caught up and can get into the corn, prioritize the areas where the stalks are weak. This is one of those seasons when it might not be a question of if you’ll have stalk rot, but rather where and how much. While we like to take advantage of as much field drying as possible, I’ve been in quite a few fields and had calls on many others, where it would be pretty risky leaving the corn out there very long.

Iowa State University Extension and Outreach Plant Pathologist Alison Robertson recommends the following procedure to assess your fields before harvest:

  • If you are scouting for stalk rot, look for lower stalk discoloration and check stalk firmness by pinching the lower internodes.
  • Simply pinch the stalk between your thumb and fingers. Healthy stalks are firm and won’t compress easily; if a node can be "squished" or if it otherwise feels soft, that means stalk rot has set in and risk of lodging goes up.
  • Instead of this "pinch" test, some agronomists and farmers prefer using the "push" test, but either way works fine.
  • Check at least 100 plants per field; 20 plants in five spots.

Testing hybrids
Better yet, try to test each of your hybrids, and give special attention to any that have low stalk rot or standability scores. So far I have seen hybrids that varied from maybe 2-4% soft to some that were well over 50%. To complicate the issue, often individual hybrids are varying quite a bit across a field. This has me asking growers to try to sample the different “management areas” they have in a field such as various tillage systems, crop rotations, drainage issues, and fertility histories and asses them separately.

Prioritize scouting toward fields that showed stress first, especially if they’ve had foliar diseases this summer or in areas where there was excess water on and off throughout the season. If about 10% or more of the stalks have issues, do your best to get those hybrids harvested first to reduce the risk of significant lodging. Have a safe and successful harvest.
 

Related articles:
Scout Now for Ear Rots
Stalk Rots and Standability Issues

Blog Post
Category: 
Tags: 
Author: 

Clarke McGrath On-Farm Research and Extension Coordinator/ Agronomist in SW and WC Iowa

Clarke McGrath currently serves as the On-Farm Research and Extension Coordinator.

Prior to joining Iowa State University, McGrath spent nearly a decade as a retail agronomist and manager in the GROWMARK system, earnin...