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Watch for Corn Stalk Lodging This Harvest

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Written Monday, September 25, 1995  

An Ohio State agronomist cautions farmers to watch for serious corn stalk lodging problems this fall due to the effect of weather and disease stresses during the growing season.

Peter Thomison says drought and hot weather during grain-fill combined with widespread late-season foliar disease damage have increased the likelihood of serious stalk rot problems in many Ohio corn fields just as they have in Indiana.

"Given these prospects, growers in some areas could incur significant grain losses if they delay field harvest to allow for natural drydown," Thomison says.

Stalks require carbohydrates produced by photosynthesis to keep pith cells and root cells alive during grain fill. However, drought and/or heat sharply reduced photosynthetic activity this summer and carbohydrate levels were often insufficient for developing ears. Stressed plants compensated by transferring carbohydrates to the ear, resulting in premature death of pith cells and root tissues. This predisposed plants to root infection and stalk rot fungi.

Environmental conditions also were favorable to foliar diseases that weakened stalks. The most important by far is gray leaf spot, while Stewart's bacterial blight was evident to a lesser degree, Thomison says. Second-generation European corn borers also injured stalks in some areas.

Other stresses that can increase the chance of stalk rot are hail damage, insect or chemical root injury, high levels of nitrogen in relation to potassium in the soil, compacted or saturated soils, and high plant populations.

In most hybrids, stalk rot symptoms do not show up until shortly before the black layer stage, coinciding with physiological maturity.

Assessing a potential lodging problem is fairly simple because the deterioration of inner stalk tissues is a symptom common to all stalk rot. These tissues will easily compress when squeezed between the thumb and finger. Use this "squeeze test" to determine the extent of stalk rot throughout a field. Give the most damaged fields priority at harvest.

"This is not the year to allow corn to dry in the field to moisture levels of the low 20's or high teens before harvest to save on drying costs!" Thomison says.


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