Stresses such as hail damage, nutrient deficiencies, diseases, insect feeding, excessively wet or dry conditions, and high winds, can lead to stalk lodging.
In general, stalk rots are favored by late-season stresses. A number of fungi and bacteria cause stalk rots in corn which can lead to stalk lodging. In addition, stresses such as nitrogen deficiency and blighted leaves from foliar diseases can inhibit the production of carbohydrates, causing plants to remobilize or move sugars from the stalk and leaves to fill the kernels. This process is referred to as stalk cannibalization and can make corn plants more susceptible to physiological stalk lodging.
Push or Pinch Test. Scout fields periodically after pollination to check for stalk rot and lodging issues. Walk a zigzag pattern through the field and test stalk firmness by squeezing or pinching each stalk at one of the lowest nodes above the brace roots. Healthy stalks are firm and cannot be compressed. If a stalk feels soft, it is likely prone to lodging. Check at least 100 plants per field.
A second method for determining potential stalk lodging is to push the plant top about 30° from upright. If plants fail to snap back to vertical, the stalk may have been compromised by stalk rot.1
If more than10% of the stalks in a field are rotted or prone to lodging, consider scheduling the field for early harvest.1 In severe instances, it may be more economical to harvest early and dry the grain post-harvest as opposed to accepting significant field losses.
1Jackson-Ziems, T.A., Rees, J.M., and Harveson, R.M. 2014. Common stalk rot diseases of corn. EC1898. University of Nebraska-Lincoln Extension. http://extensionpublications.unl.edu/. Web source confirmed 07/30/18. 180801072030