What Causes Sweet Corn Leaves to Turn Brown & Crack?

Irrigation

• Corn plants have shallow roots, which affects the amount of water they need to thrive. The closer roots are to the surface the less capable they are of absorbing deep ground water. Corn grown in water-retentive loamy soils should receive 1 inch of water per week. Corn grown in porous soil should be watered more frequently, while those planted in clay soils should be watered less. One way to test whether your corn needs irrigation is to stick your finger into the soil. If the soil is dry or does not stick to your finger then you need to water your crop. Avoid flooding by watering with 1 inch of water, allow it to drain and then water again until the soil is moist. Poorly irrigated corn will dry out. Foliage turns brown and cracked, and ears do not form.

Fungus

• Your corn rows may appear green and healthy but upon closer inspection you may notice brown spots on the leaves, which most likely are caused by a fungal infection. Once the infection has set in, the crop likely will be too damaged to save. At this time you may see brown leaves and damaged stalks. Diseased stalks should be burned. Do not compost the material as this will only lead to future diseased crops.

Prevention

• Fungal infections generally are spread through overhead watering systems. The fungus is water-borne and drips down across leaves, where it eventually settles and begins using your corn as a host. One way to avoid fungal damage is to water your corn using drip line irrigation rather than overhead irrigation.

  Do not plant your corn in an area that has been exposed previously to fungal problems. Before planting corn seeds, choose resistant varieties. If your corn already is in the ground, and is showing early signs of brown spots and leaf damage, then apply a fungicide in accordance with manufacturer's directions. You also may wish to take a leaf sample to your local university extension master gardener for analysis and recommendations.

Fertilization

• Fertilizing your soil with high nitrogen fertilizers gives your corn crop a chance for success. Corn is a heavy feeder and if you do not supply the crop with adequate nutrients then it is more prone to succumb to disease. Test your soil before planting, and amend the soil with nitrogen, phosphorous and potassium as indicated by your soil test recommendations. You should continue side-dressing with nitrogen throughout the growing season, especially when ears are developing.