Corn standability depends on a combination of plant quality, stalk strength, and root strength. Stalk lodging is the breakage of the stalk below the ear. Root lodging results from the root system’s inability to anchor the plant and keep it vertical, which causes the stalks to lodge.  

Severe lodging is a widespread problem for corn growers throughout the U.S., leading to annual yield losses of 5% to 25%. Lodging can also reduce the quality of the harvested grain. 

“Predicting when stalk lodging has occurred can be difficult,” said Jeff Shaner, Regional Product Manager for AgVenture, Inc. “Lodging may be caused by the combined impact of several factors where one field may develop stalk rot and the field next to it won’t.” 

At harvest, some of the leading causes of corn standability issues include: 

• Stalk and root deterioration by cannibalization due to stress late in the season 

• Stalk deterioration due to stalk rot-causing pathogens 

• Insect feeding from pests like corn rootworms 

• Corn product with insufficient root or stalk strength 

While growers should scout fields regularly throughout the growing season, early to mid-September is critical for checking stalk integrity. During this time, growers should be able to assess stalk rot development, determine the extent of insect damage to stalks and roots, and finalize the field harvest order.  

Pinch and push tests can both be utilized to estimate the amount of stalk rot in a field. Weak stalks are detected by pinching the stalk at the first or second elongated internode above the ground. If the stalk collapses, advanced stages of stalk rot can be assumed. 

Growers can also check stalk integrity by pushing the plant sideways about 8 to 12 inches at ear level. Stalk rot is indicated if the stalk crimps near the base or fails to return to the vertical position. 

“The goals of these tests and surveying fields are to determine if any corn standability problems are only in one area or if they’re spread throughout the field,” says Shaner. “This helps determine which fields to harvest first and the speed at which they should be harvested.” 

In most situations, harvesting lodged fields or field areas before the well-standing fields is better. This strategy must be evaluated on a case-by-case basis, however. For instance, if better-standing corn is ready for harvest, it may be more efficient and cost-effective in some cases to harvest it first before lodging increases there.  

When harvesting, going slower can pick up and save more ears from lodged plants. Under severe stalk lodging conditions, harvesting against the direction of the lodging is usually an advantage. Some fields may lodge worse as time progresses, especially if a stalk rotting disease such as anthracnose is present. Watch these fields closely.