Wheat hit with rust, scab

Stripe rust, a crop disease seldom found in Minnesota and North Dakota, has popped in wheat fields in northwestern Minnesota and elsewhere. But warm weather in late June and early July should prevent the disease from becoming a major problem, off...

Stripe rust, a crop disease seldom found in Minnesota and North Dakota, has popped in wheat fields in northwestern Minnesota and elsewhere.

But warm weather in late June and early July should prevent the disease from becoming a major problem, officials say.

Scab, a crop disease often found in the region, is present again this year, too. Fusarium head blight, or scab, reduces both quality and yields.

A little background:

Stripe rust, leaf rust and stem rust can all infect wheat and hurt yields and quality. Of the three, leaf rust in the most common in this area, stripe rust the least common.


Stripe rust and leaf rust look much alike.

Stripe rust, also known as yellow rust, consists of pale, orange spores in long stripes on the leaf.

Leaf rust is reddish-orange and found in masses of round spores.

Stripe rust needs cooler temperatures -- below 60 degrees at night -- and fares well in the Pacific Northwest. It also occurs in the Southern Plains' winter wheat crop.

Mid-summer temperatures normally are high enough to prevent stripe rust in North Dakota and Minnesota.

This year, however, wet, cool weather has allowed stripe rust to occur in areas where the disease typically isn't found, says Marcia McMullen, plant pathologist at North Dakota State University in Fargo.

The disease isn't widespread and most cases have been found on test plots in winter wheat and spring wheat varieties not commonly grown in the state, she says.

Warm weather, including temperatures in the high 80s and 90s during the long Fourth of July weekend, should stop the disease, she says.


Fungicides that are effective against scab also work well against stripe rust, she says.

Scab, a longstanding problem for area wheat farmers, is occurring again this year in North Dakota. In late June and early July, there was a "moderate to high risk of infection" across the state, according to NDSU.

But the risk was expected to fall dramatically because of the high temperatures and strong winds during the Fourth of July weekend, McMullen says.

Farmers should continue to check their crops for disease to see if spraying is warranted, she says.

'Almost a novelty'

Minnesota's wheat crop already has suffered from excess moisture, and crop disease, even if ends up being only minor, won't help, says Dave Torgerson, says executive director of the Minnesota Association of Wheat Growers in Red Lake Falls.

"It's been so wet that we've seen a little" stripe rust this year, he says.

Frequent winds have hampered spraying chemicals to fight crop disease, he says.


Stripe rust is "almost a novelty" in northwestern Minnesota because it occurs there so seldom, says Jochum Wiersma, University of Minnesota extension agronomist in Crookston.

This year in northwestern Minnesota, "the incidence has been low, but we can find it," he says.

Dry weather recently has limited the disease, he says.

Using fungicide against scab also has helped to hold down stripe rust, he says.

The risk of scab is greatest in the northern Red River Valley and in the eastern part of the state, according to information from the Minnesota Association of Wheat Growers.

SD, Montana outlook

South Dakota wheat farmers are concerned about scab, but the disease doesn't appear to be a major problem this year, says Randy Englund, executive director of the South Dakota Wheat Commission in Pierre.

"I've seen a few heads with scab, but it's rare," he says.


Warm weather recently has helped reduce the threat of scab, he says.

Traditionally, stripe rust is less unusual in South Dakota, particularly in winter wheat, than in North Dakota and Minnesota.

The disease is present again this year in South Dakota, but isn't a major worry, Englund says.

Stripe rust isn't uncommon in Montana because of the state's cool nights, says Mary Burrows, plant pathologist with Montana State University in Bozeman.

The disease has popped up again this year, but doesn't appear to be a serious concern, she says.

Scab also is present this year, though the extent and severity of the disease probably won't be known until mid-July, she says.

Weather conditions that promote good yields also tend to promote disease, she notes.

"Good for yield potential, good for disease," she says.


Online crop disease tools

Several websites have regularly updated information on crop disease conditions.

North Dakota State University's Small Grains Disease Forecasting Model helps area producers figure out if their crops are at risk of disease.

Automated computer models, which take into account past weather conditions, estimate how susceptible crops are to a particular disease in their current stage of development.

The site, , has information for locations across North Dakota, as well as in western Minnesota, northern South Dakota and eastern Montana.

Minnesota famers can get information at . Farmers in 22 states, including North Dakota, South Dakota and Minnesota, can get customized forecasts for scab at . Click on the underlined "tool" in the center of the page.

Information: .

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