What is in this article?:
- Early season stresses affecting Louisiana corn
- Zinc deficiency
- Cold temperatures have been the biggest challenge for Louisiana corn producers this season.
- LSU AgCenter specialists say producers need to watch corn closely for symptoms of stress and damage.
- Nitrogen management is also crucial in cold, wet growing conditions, they say.
CORN WITH frost damage, however growth point is still active.
The first and probably highest probability is zinc deficiency. While zinc uptake is less than for the macronutrients N, P and K, it does not make it any less important. Zinc deficiencies are actually somewhat common to Louisiana. However these deficiencies have normally been located in the Red River alluvial soils. The increasing incidence of zinc deficiencies in the upland loess of the Macon Ridge and Mississippi alluvial soils are a growing concern.
The other nutrient deficiency that could cause symptoms is sulfur. While sulfur deficiencies do not typically present with striped sclerosis, many agronomists from around the United States have reported sulfur deficiencies as interveinal chlorosis (striped sclerosis).
While this early-season, striped chlorosis can be easily attributed to a soil nutrient deficiency, cool and wet conditions could potentially be causing the symptoms. These cold, saturated soils can inhibit early root development, as mentioned earlier, and limit the ability of corn plants to access available nutrients. Therefore, plants are experiencing nutrient stress when adequate supplies are available – the roots are just not able to access them.
To determine the cause of this early-season deficiency symptom, both plant and soil samples need to be collected. While tissue samples might tell you what’s causing the symptoms, correcting for the symptoms depends on whether the crop is not able to access the nutrient or if adequate nutrients are not present in the soil. When collecting a sample to determine nutrient deficiencies, samples need to be collected from areas of the field that appear to be growing well without symptoms and from problem areas of the field that are exhibiting the deficiency.
Nitrogen management decisions are critical in corn production. Additionally nitrogen has a high degree of losses throughout the growing season. Two of the most important loss mechanisms for Louisiana are denitrification and leaching. Both are associated with heavy precipitation events and periods of high soil moisture, similar to what we have experienced in recent weeks.
While these conditions themselves do indicate high nitrogen losses, it is something that needs to be monitored closely in the coming weeks. With increasing temperatures and drier conditions hopefully in the future, growers, agents and consultants need to keep an eye out for signs of nitrogen deficiencies that could indicate a high amount of early-season nitrogen losses.
In corn, chlorosis will begin at the tips of the older leaves and will continue to progress along the mid-vein. In severe cases, chlorosis will spread to the leaf margins and will begin to turn necrotic. Eventually these leaves will drop prematurely, and if the deficiency continues, will progress further up the plant.
However nitrogen is a nutrient which does respond very well to rescue fertilizer applications through mid-to-late vegetative stages.