Some Ohio Corn Experiencing Stalk Lodging

October 5, 2010

COLUMBUS, Ohio – Some corn throughout Ohio, already stressed from lack of adequate moisture, is experiencing stalk lodging and stalk rot.

"Recent storms accompanied by strong winds have resulted in stalk lodging in localized areas across the state," said Peter Thomison, Ohio State University Extension state agronomist. "The rapid maturation and dry down of the corn this year may affect the crop. We've already received reports of kernels falling off ears, reduced shank strength, ears dropping, and exposed ears in some hybrids."

Thomison encourages growers to avoid harvest delays in order to minimize losses from stalk lodging or rot damage.

"Identify which fields are at greatest risk and harvest those fields first," said Thomison, who also holds an appointment with the Ohio Agricultural Research and Development Center. "Fields which experienced late-season drought stress or extensive northern corn leaf blight or gray leaf spot would be prime candidates for early harvest. Now is not the time to keep corn in the fields to save on drying costs."

According to the Ohio Agricultural Statistics Service, 36 percent of Ohio corn has been harvested, far ahead of this time last year and the five-year average. Abnormally dry conditions and hot weather late in the season rapidly matured the crop and drove growers into the fields to harvest up to three weeks ahead of schedule.

"The presence of stalk rots in corn may not always result in stalk lodging," said Thomison. "It's not uncommon to walk fields where nearly every plant is upright, yet nearly every plant is also showing stalk rot symptoms."

Thomison said that a symptom common to all stalk rots is the deterioration of the inner stalk tissues so that one or more of the inner nodes can easily be compressed when squeezing the stalk between thumb and finger.

"It is possible by using this "squeeze test" to assess potential lodging if harvesting is not done promptly," said Thomison.

The "push" test is another way to predict lodging.

"Push the stalks at the ear level, 6 to 8 inches from the vertical. If the stalk breaks between the ear and the lowest node, stalk rot is usually present," said Thomison.

For a corn plant to remain healthy and free of stalk rot the plant must produce enough carbohydrates by photosynthesis to keep root cells and pith cells in the stalk alive and to meet demands for grain fill. When corn is subjected to drought stress during grain fill, photosynthetic activity is reduced. As a result, the carbohydrate levels available for the developing ear are insufficient. The corn plant responds to this situation by removing carbohydrates from the leaves, stalk, and roots. While this "cannibalization" process ensures a supply of carbohydrates for the developing ear, the removal of carbohydrates results in premature death of pith cells in the stalk and root tissues, which predisposes plants to root and stalk infection by various fungal pathogens.

Author(s): 
Candace Pollock
Source(s): 
Peter Thomison