Healthy Corn Leaves Power Yield Potential

WILSON HENRY

GOODLAND, KANSAS

   The presence of foliar disease around the tasseling stage in corn development can lead to significant yield loss. Yield potential is impacted when the top eight to nine leaves above the ear become riddled with disease. These leaves contribute at least 75 percent of the energy needed to add carbohydrates and grain to the ear.1 Much of a corn plant’s energy from photosynthesis is produced by the foliage surrounding the primary ear, so it is important to protect the integrity of those leaves from damage.

   As corn matures from the vegetative stage to the early reproductive stage, symptoms of foliar diseases may start to appear in fields. 

   Diseases to look for are northern corn leaf blight, gray leaf spot,rust and anthracnose leaf blight. Also evaluate corn plants for bacterial diseases that are not controllable with fungicide applications such as Goss’s wilt, Stewart’s wilt and bacterial leaf streak.

   Fungicides don’t increase bushels but do protect yield potential from some foliar diseases. The decision to apply a fungicide should be based on field evaluations, environmental conditions, management practices, disease pressure, and potential economic advantage with cost of the fungicide application balanced by the potential yield increase. Several fungicides can help manage many of the foliar fungal diseases that attack corn.

   For the best economic return, in most situations, fungicide applications should be applied between tasseling and the early silk stage. Foliar fungicides are typically active for 14 to 21 days, and an optimal application can protect leaves from fungal diseases during grain fill.

   As many corn fields approach the reproductive growth stage in Kansas, farmers can consider these tips to enhance yield potential:

   • Getting out in the field and making spray decisions early will allow you to get the most benefit from your fungicide application.

   • Using a high-quality fungicide with multiple modes of action can help prevent yield loss to many of the fungal pathogens that put a corn crop at risk.

   • Work closely with your local Seedsman to determine the right fungicide program for your operation.

   Visit the Channel.com Agronomy Library for an article titled “Managing Early Onset Diseases in Corn” with photos and descriptions of corn diseases.

   1 Rees, J.M. 2008. Gray leaf spot of corn. G1902. University of Nebraska. ∆

   WILSON HENRY: Channel Agronomist