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Corn Illustrated: You should think about next summer’s disease potential now.

Dave Nanda

December 19, 2016

3 Min Read

Thinking about leaf diseases during winter is probably the last thing on your mind. You will be working on your planter this winter and not thinking about next summer. Hopefully, Mother Nature will be kinder this year and won’t favor disease organisms like she did last year.

However, lots of inocula of various disease organisms are on the ground, ready to attack if the conditions are conducive. Be prepared to protect your crops.

Here are six tips to help you start planning for 2017 disease control in corn.

1. Rotate crops. Avoid planting corn after corn in 2017, if possible.

2. Plan on using foliar fungicides, if needed. Last year, fungicides applied on time certainly paid off. Mark and Scott Henderson, Franklin, Ind., report that foliar fungicide applications made after pollination was complete yielded 15 to 20 bushels per acre more compared to where no fungicides were used. A large grower in Ohio says he’s going to get his sprayer ready so he can apply fungicides to all of his corn, as well as soybeans in the future, if needed.

3. Select the best resistance package. But realize that a hybrid resistant to everything is nearly impossible to develop. Plant breeders try to develop new hybrids with the highest yield potential and select for disease resistance at the same time. However, it’s almost impossible to achieve resistance to all prevalent diseases while developing new hybrids. Disease organisms are constantly changing. By the time breeders develop hybrids resistant to certain disease organisms, pathogens change.

4. Know how to use fungicides to protect corn. How do you decide if you need to spray, and what is the best time to do so? Start by looking at the organisms. Different diseases become more prevalent in certain growing conditions. Northern corn leaf blight likes cooler temperatures, and gray leaf spot likes high humidity and high temperatures. Conservation tillage has increased the incidence of many diseases.

Some popular corn hybrids on the market have very high yield potential but are very susceptible to certain pathogens. These susceptible but otherwise high-yielding hybrids help create more disease inocula for the following year since they’re grown on a large number of acres. 

5. Use planting date and relative maturity choices as tools. Planting date and relative maturity of hybrids can also affect the development of certain diseases. Earlier-maturity hybrids can sometimes escape disease. You need to protect the leaves above the ears because those leaves contribute most of the yield.

6. Plan a scouting program, and scout all season long. My scouting experience during the last few years has shown that you don’t have to apply fungicides to all hybrids, or even all fields planted on different dates, because some fields might escape disease. But it’s very important to keep scouting. The ideal time to apply fungicides is after pollen shed is complete and silks start to turn brown. You want to protect leaves during grain fill. Fungicides don’t increase yield, but they can protect the yield potential of the crop in the presence of fungal diseases.

Nanda is president of Agronomic Crops Consultants LLC. Email him at [email protected], or call him at 317-910-9876.

About the Author(s)

Dave Nanda

Dave Nanda is director of genetics for Seed Genetics Direct, Jeffersonville, Ohio. Email [email protected] or call 317-910-9876. Please leave a message.

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