4 Ways to Keep Scab at Bay

4 Ways to Keep Scab at Bay

In 1999, wheat grower Lee Lubbers first learned a thing or two about scab. Located at the southern tip of South Dakota, Lubbers’ farm was the first verified case of widespread Fusarium head blight on winter wheat.

“We were walking our fields toward the end of the 1990s, and there was an unfamiliar disease on our wheat heads,” Lubbers explained. “I talked to our local county agent, and he had never seen anything like this in winter wheat before, so we went through some college text books.”

When Lubbers identified the disease as scab, he called South Dakota State University. The state researchers tested his wheat the next morning and confirmed six areas on his farm were contaminated with scab. 

Those six areas were a sore spot for Lubbers. Instead of yielding in the 90-100 bu/A range like his other wheat crop, the scab-infected grain averaged 30-35 bushels, not to mention getting hit with a significant discount at the elevator.

Sixteen years later, wheat growers from Pennsylvania to Illinois and Kentucky to Montana are wary of spotting a pale pink on their spring or winter wheat heads. When Ohio State University researchers cite 10-15 percent of a field contaminated by scab can lead to a crop loss of 50 percent or more, waiting and hoping on cool conditions aren’t much of an option. Now that a number of Midwest grain elevators have set discounts for vomitoxin levels between 6 – 10 ppm in the 40 cent-to-$2/bu range, to hope you’ll get lucky and not see scab this year isn’t the safest route.

Take Action & Prevent Scab:

  1. Variety Selection: If you’re a hard red spring wheat producer, each state has a number of varietal options that provide moderate to intermediate resistance to Fusarium head blight, all while simultaneously possessing competitive levels of key agronomic traits. This includes grain yield, test weight and straw strength, along with essential quality traits such as protein content.

  2. Heat & Humidity: This is the biggest factor that determines the significance of disease. The disease favors moderate temperatures of 56-86 degrees Fahrenheit and a high relative humidity exceeding 90 percent, so keep a close watch on the forecast. However, scab can still crop up in your wheat, even under ideal weather conditions.

  3. Online Assessment: When wheat is at the early flowering stage, check the national Fusarium prediction model that provides a local, daily risk assessment of scab. But this is not foolproof.  The model is correct only 75 percent of the time, so consider past field history and consult a local crop specialist to confirm.

  4. Apply a Fungicide: To fend off Fusarium with a fungicide such as Prosaro®, it is critical that applications are made during early flowering.  Depending on air temperature, this timeframe is usually one to two days before anthers become visible on the main stem heads until five or six days after anthers appear on the middle florets of the heads.

Even with the breakthrough of scab-resistant varieties, heat and humidity index insights and a localized Fusarium prediction model, Lubbers knows he’ll face scab almost every year, unless he treats with Prosaro fungicide.

“We use Prosaro at early flower and at bloom on the wheat for Fusarium head blight. If we did not use Prosaro, we would not be able to raise wheat anymore, we would just have a flop for a crop,” Lubbers explained.

After Lubbers found his fields infected with Fusarium in the late 1990s, he tried several other competitors before finding Prosaro. “We tested several other fungicide options in our winter wheat fields, but they only provided 50-60 percent control; with Prosaro, we get 90-100 percent. Prosaro is the premiere product, and cost wise, it’s very competitive.”

Over the past decade, hundreds of wheat growers across the states have gotten docked for not meeting national scab standards. Not so for Lubbers. He sells nearly 6,000 acres of seed wheat across three states and consistently has quality germinations and therefore, quality at market. “Since we first started using Prosaro, we have never been rejected on a load. We actually sell some milling grade – for everything from Malt-O-Meal to dog food – which they are very sensitive about, because both will be consumed by humans or animals,” Lubbers said. “We never get a discount, we actually get a premium for our wheat.”

Scab costs growers millions in profit each year. It is good to know there are researchers dedicated to eliminating the worst of all wheat fungi. One such facility, Brownstown Agronomy Research Center at the University of Illinois, has nearly 1,500 scab-resistant variety tests underway. Of those, only 300-400 make it to preliminary field tests each year. Several more steps follow that threshold, including multiplication, advanced performance tests and multi-state evaluations.

Though the research process is lengthy and complex, it is one that will be worth the wait. Over the past few years, researchers at Brownstown Agronomy Research Center have been getting close to combining genes that will be acceptable for producers – traits that balance strong scab resistance with high yields – and good test weights. 

Until then, Lubbers plans to keep profiting with Prosaro. “Ultimately, we would be lost without Prosaro. It has saved the day for us.”

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