Agronomy Talk

Agronomy Update

Diseases Making an Appearance in Indiana

Published on Tuesday, July 7, 2015

After a very wet start to the growing season, diseases are beginning to show in corn fields throughout the state. Check out Christy's notes below on what you can expect to find in the coming weeks.


Gray Leaf Spot and Northern Corn Leaf Blight in Early Stages
Christy Kettler | Sales Intern | Central Indiana
June 29 - July 2, 2015

Gray leaf spot (GLS) will begin appearing as small rectangular blocks of a tan color surrounded by jagged edges of brown. You can see an example of this in the photo below. As the disease progresses, the spots will extend between veins to long lesions of gray, tan and brown. 

Gray leaf spot 

Northern corn leaf blight (NCLB) is often easily recognized due to its spots shaped like cigars which can grow between 1 and 6 inches in length. These lesions show up as a tan and olive green color on the leaves and will cross over veins, unlike GLS lesions. Both diseases are likely a result of the humid conditions and moderate temperatures. These lesions will appear in the lower leaves first and make their way up the plant after tasseling.

Management of GLS and NCLB will be determined on the growth stages and how far up the plant lesions have moved. Spraying a fungicide after pollination is the best option for controlling disease. You can avoid additional stress on the crops by waiting to spray until pollination is complete. The stress of spraying around tassel time can limit pollination and leave some kernels unfertilized. 

Northern corn leaf blight

Additional findings show that European corn borers are still feeding on non-GMO crops. The insects can damage plants and move on to the next ones down a row, leaving behind a damaged tassel wrapped in the whorl. Controlling the spread of these borers is a very timely task. Catching egg masses and spraying an insecticide before they have a chance to burrow down into the stalks is key to this control.


We have also found that nitrogen loss is causing devastation to many fields across the state, especially in the northern regions. Saturated soils are leaving roots struggling to find nutrients and oxygen. Some fine roots have resorted to reaching the soil surface to find oxygen. The yellow areas of fields with shorter and stunted plants are the result of excessive water for an extended period of time. These areas are likely to fall further behind in maturation and hurt final yields.  

The traps throughout north central Indiana have shown some European corn borer moth flight action. 


If you have any questions about these findings or would like more information, please reach out to myself or your seed advisor. 

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Denny Cobb

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