Managing diseases is an evolving science. New diseases appear, old diseases reappear, fungicides change and the weather remains consistent by always changing year by year. All of these present challenges to growers and plant pathologists alike.

Early steps can help manage diseases in corn, soybean and other crops.

“The first step, and probably the most important step,” according to LSU AgCenter plant pathologist Boyd Padgett, “is choosing disease-resistant varieties and hybrids.”

And it makes perfect sense from an economical and time-saving perspective.

“Disease-resistant varieties and hybrids are generally no more expensive, but they can save time and money by potentially avoiding a fungicide treatment,” Padgett said.

In some years, disease outbreaks are limited, but in other years, outbreaks can be severe. The driver for these outbreaks is typically environmental conditions, with moisture and temperature being the biggest contributors for certain disease epidemics.

Padgett says newer fungicides are showing better efficacies, so there are some new tools in the toolbox.

“I’ve seen yields 20 bushels higher in fields with late-planted beans that had a fungicide applied in a timely and effective manner,” he said.

Padgett also said many producers spray crops, particularly soybeans, as a precautionary measure. This is an added cost that producers could avoid, especially if environmental conditions are not conducive to disease development.

“For example, if there is an extended dry period during flowering, you probably don’t need to treat,” Padgett said.

Since a fungicide application can run as high as $20-25 an acre plus an application cost, a farmer could save a good deal of money and time by planting a resistant variety.

With depressed commodity prices, farmers are having to be creative when it comes to managing input costs. One way to reduce costs could be forgoing a seed treatment on soybeans. While research has shown they are effective, they typically do not pay for themselves and serve as more of an insurance policy during less-favorable growing conditions.

If diseases such as frogeye leaf spot, aerial blight or Cercospora leaf blight are severe enough to warrant a fungicide application, researchers have documented that products containing SDHI, or succinate dehydrogenase inhibitors, and/or newer triazole fungicides have been effective in helping control these diseases.

“These newer fungicides are tank-mix products that carry with them two or three modes of action,” said Trey Price, plant pathologist at the AgCenter Macon Ridge Research Station in Winnsboro. “This makes them more effective against diseases.”

Taproot decline is another problem that Price is examining. It is a problem for which coming up with an answer hasn’t been easy.

“There are a couple of in-furrow fungicides that are effective on taproot disease management,” he said. “However, most farmers do not want to use that type of application.”

Like Padgett, Price believes farmers need to find a resistant variety and rotate.

Price noted that taproot decline management is most successful when treatments are done at planting.

“It needs to be done at planting and through in-furrow applications,” Price said. “This is now somewhat unconventional, and growers have been reluctant to take this approach.”

Trying to grow agronomic crops in a state that has a subtropical climate presents many challenges, and plant pathologists are on the frontline looking for answers to the many questions regarding disease management.