Is fungicide in wheat worth it?

By Chris Suber, president of Ebberts Field Seeds, Inc.

Chris Suber, president,
Ebberts Field Seeds, Inc.

There’s no shortage of things to do during May for Ohio farmers. Whether it’s working ground, planting, or spraying, every hour counts when conditions are fit to be in the field. Yet an important application in wheat still needs to get done among the chaos of getting the corn and soybean crop planted and off to a good start — a fungicide pass when the wheat is at the heading stage to manage Fusarium Head Blight (FHB), commonly known as head scab.

For most Ohio farmers, this pass typically falls in the middle of May. Although this year Ohio’s wheat crop appears to be a full week to 10 days ahead of typical. One of the last things a farmer wants to do during this busy time is clean the sprayer out just to spray a few fields of wheat, especially when you’re trying to finish soybean burndown or spray corn. This cleanout isn’t just a rinse and move on either. There are likely a few residual products in the sprayer, including glyphosate that could wreak havoc on the wheat crop. For these reasons, most growers opt for aerial application to ensure a safe and timely fungicide application to the wheat crop.  

Many growers ask us each season, “Do we still need to be spraying for head scab?” I think this is a fair question to revisit each year on whether investing an additional $30 to $40 per acre on fungicide near the finish line of a low budget wheat crop is worth it. This is an especially important question considering many wheat genetics sold today carry the FHB1 gene that delivers partial genetic resistance to head scab. In my experience, the FHB1 gene won’t eliminate the presence of head scab, but it does a great job at minimizing it to much lower levels when scab infection could be severe. Like many things in farming, it boils down to risk, and how to economically manage that risk. So, the question should be asked, what’s the big risk with head scab?

Head scab is a Fusarium related fungus that affects wheat yield and overall grain quality. Scab infected kernels appear bleached, are lighter in weight, and can carry high levels of vomitoxin reducing the feed value and marketability of the grain. Much like corn, higher than acceptable levels of vomitoxin detected in ppm (parts per million) lead to substantial discounts, or rejection from grain buyers. Wheat heads can be infected when wet humid weather is present during the wheat flowering or heading stage.

Ohio State University Extension research states that 2 or 3 days of rainfall or extended periods of high humidity significantly favors scab infection. The fungi causing scab are all members of the genus Fusarium, which can overwinter and survive in several crop residues including cornstalks. Therefore, it’s safe to assume that Fusarium will continue to thrive in our growing environment for the foreseeable future. And head scab for that matter, could flare up if the disease triangle is met between pathogen, host, and environment.

Considering all the risks involved, most notably with risk to grain quality from vomitoxin, it is my opinion to make a fungicide pass at heading for wheat every season. Even though we have great wheat genetics with the FHB1 gene for genetic resistance, the combination of having the gene resistance plus applying fungicide nearly eliminates the threat of scab. I believe ensuring grain quality from a marketability standpoint is critical. We can do everything right from a management perspective, but if we can’t market the grain, or have substantial discounts at delivery, profitability is lost very quickly. According to OSU Extension research, fungicide applied at heading can provide up to 60% to 75% control against head scab. In terms of fungicide choices, we’ve seen good results from Miravis Ace. The SDHI molecule in the Miravis Ace product package is promoted to provide a wider window of application in addition to improved efficacy. Since the wheat flowering window happens rather quickly, having a little extra time to get applications made on the front, or back end of heading can make a huge difference.

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