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The integrity of corn stalks may have been compromised this year because of physiological stalk rot. Physiological stalk rot can be a function of high kernel count, well filled kernels, favorable growing conditions, and agronomic factors.
Physiological stalk lodging is usually the result of an interaction between weather, fertility, compaction, leaf disease, plant population, planting date, and kernel fill. Ultimately, anything that reduces photosynthesis and the production of carbohydrates (sugars) may negatively impact stalk integrity.
Grain fill takes priority over other plant functions and if necessary, the stalk can be cannibalized of nutrients and water to fill kernels. Physiological lodging can be just as severe as stalk lodging due to stalk rot pathogens; however, since pathogens may not be the cause, the interior plant pith may appear white in color. Alternatively, fungi may colonize predisposed tissues giving the appearance of stalk rot even though the primary cause is physiological.
High plant populations can affect standability if the growing season and other interactions are not supportive of the population. Planting date can also be a factor as favorable early-season weather helps in the determination of kernel row number, which occurs around the fifth leaf stage (V5). Poor weather during that time frame can decrease kernel number. Drought conditions or prolonged periods of cloudy weather during grain fill can force the plant into stalk cannibalization to support grain fill. Stalks can deteriorate if a nutrient imbalance or loss.
Actual lodging did not occur in most fields because weather for most of the harvest season was without high winds that could have potentially caused the stalks to break. Insect resistant corn products helped reduce additional stress from poor roots or corn borer damage. Additionally, corn products with resistance to diseases such as gray leaf spot or were timely treated with a fungicide were helped by not losing photosynthetic producing leaf tissue.
To help guard against physiological stalk lodging in the future, corn products with insect resistance, disease resistance, drought tolerance, and with very good standability characteristics should be selected.
Pathological stalk lodging can be caused by the presence of one or more stalk rot diseases. Common stalk rot diseases associated with lodging include anthracnose, diplodia, fusarium, gibberella, and charcoal stalk rots. Please refer to Identifying Stalk Rot and Managing Potential Lodging Issues for additional information.