Suppress Disease With a Fungicide Application at Feekes 10.5.1

Small grain crops for wheat fungicide application
Making a Prosaro® fungicide application at Feekes 10.5.1 can help suppress scab and DON levels in small grain crops.

With an unbeatable spectrum of disease control, Prosaro® fungicide improves grain quality and maximizes yield, as well as profit potential. This broad spectrum of disease control includes Fusarium head blight (FHB), or scab, glume blotch, Septoria leaf spot, powdery mildew, tan spot and rusts. Of the many wheat diseases Prosaro controls, one of the most economically damaging is scab.

Dr. Andrew Friskop, Extension cereal crop plant pathologist at North Dakota State University (NDSU), was able to answer some questions about the disease and the importance of an optimally timed fungicide application to suppress scab in wheat. At NDSU, Dr. Friskop is an applied researcher, studying and testing various field management solutions to help update and share recommendations to small grain and corn growers across North Dakota.

What is scab in wheat?

According to Dr. Friskop, scab is one of the most important small grain diseases to manage in the United States. Not only does scab rob yield, it also produces the mycotoxin, deoxynivalenol (DON), which reduces grain quality and can lead to more dockage at the point of sale.

Scab is caused by Fusarium graminearum, a residue pathogen that can survive on corn and small grain residue.  Dr. Friskop indicated that the pathogen is well-equipped to survive any environment. However, Friskop also noted that the one factor that really drives the disease is humidity, which is heavily monitored a couple of weeks before heading and during the flowering process.

“In North Dakota, we call it the Fourth of July disease because, I feel like every year at least some of the small grain crop is heading and flowering around the Fourth of July,” said Dr. Friskop. “And if we have a very humid and warm Fourth of July, we often start thinking scab.” 

What is the optimal time to apply a fungicide to control scab in wheat?

Dr. Friskop says the most optimal time to make a fungicide application for scab is at Feekes 10.5.1., or early flowering. This growth stage is described as when yellow anthers start to protrude from the center of the head.

“If you see that stage at 50 to 80 percent in the field, that’s going to align with the current recommendation as far as being the best time to make a fungicide application,” said Friskop. “And what we’ve found the last couple of years, whether it is durum or spring wheat or winter wheat, that recommendation has held pretty true to form.”

Multi-university research demonstrates that when applied at the recommended timing of Feekes 10.5.1, fungicides help provide good scab control, suppression of DON and protection of yield potential. In trials, the highest levels of efficacy were observed when a fungicide application was made at early flowering, compared to applications made at head emergence.1

What are the benefits of applying a fungicide at Feekes 10.5.1?

Research done in late 1990s and early 2000s has shown that the scab fungus can start infecting the plant any time from full head emergence up to the soft dough stage. However, Friskop noted that the greatest likelihood of infection is at early flowering. One of the main reasons for this is that spores use spent flower parts as a food source at this growth stage.

“When you think about the benefits of applying a fungicide to line up with that early flowering stage, the fungicide is helping create that barrier to prevent the infection that is going to otherwise occur at this timing,” said Friskop. “And, by allowing a good fungicide suppression, you are also going to protect some yield.”

What are the risks of applying a fungicide too early or too late, and not at Feekes 10.5.1?

When it comes to applying a fungicide at the right time, applying too early is riskier than applying too late, according to Dr. Friskop.

“Being too early, in some cases, you might not get good wheat spike coverage,” said Friskop. “And that kind of revolves around a fungicide is only as good as it covers. Fungicides don’t move a lot [in a plant], so that’s why protecting wheat spikes becomes very critical.”

On the other hand, applying a fungicide after Feekes 10.5.1 may not be as much of a risk. “A fungicide application made within seven days after early flowering should be okay,” said Friskop. “We are still getting good DON suppression and that’s showing up quite consistently in our eastern and western North Dakota trials.”

What active ingredients would you recommend growers use to manage scab?

When it comes to selecting a fungicide to apply at Feekes 10.5.1 for scab control in wheat, Friskop mentions that there are effective active ingredients in the triazole class. 

“What we’ve found in our research is that our two most effective active ingredients in the triazole class are prothioconazole and metconazole,” said Friskop. We also have tebuconazole, which also offers some suppression.” 

Prosaro fungicide includes both prothioconazole and tebuconazole as active ingredients. Learn more about Prosaro here.

Any other recommendations for managing scab in wheat?

In addition to making a fungicide application at Feekes 10.5.1, Friskop recommends selecting a variety that is resistant to Fusarium head blight.

“When you use a good level of resistance in your variety with a fungicide, you can increase your ability to reduce disease almost 70 to 80 percent in some cases,” Friskop said. “A good variety selection not only puts less pressure on the fungicide, but also allows the fungicide to keep the scab levels in check and keep the DON levels under what can be accepted at the point of sale as well.”

To learn about Bayer Cereal Solutions, contact your Bayer Cereal Expert.

Bayer Solution

Prosaro fungicide has two effective active ingredients that not only provide control of scab, but also other head diseases, such as glume blotch and foliar leaf diseases including rusts, tan spot, powdery mildew and Septoria leaf blotch.


ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Performance may vary, from location to location and from year to year, as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible and should consider the impacts of these conditions on the grower’s fields.

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Works Cited

  1. Paul, P.A., Bradley, C.A., Madden, L.V., Dalla Lana, F., Bergstrom, G.C., Dill-Macky, R., Esker, P.D., McMullen, M., Grybauskas, A., Kirk, W.W., Milus, E., and Ruden, R. Effects of Pre- and Postanthesis Applications of Demethylation Inhibitor Fungicides on Fusarium Head Blight and Deoxynivalenol in Spring and Winter Wheat. Plant Disease, 2018. https://apsjournals.apsnet.org/doi/10.1094/PDIS-03-18-0466-RE

Check out the following resources for more information about the broad spectrum of diseases controlled by Prosaro:


Be Ready for Any Scenario This Season with Prosaro® Fungicide


Wheat Rust Diseases


Powdery Mildew in Cereal Crops


Pest Profile: Wheat Scab

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