Small Town News

Wheat, barley at risk for critical diseases in 2010

---

Loose smut continued to infect wheat and barley fields in 2009 across North Dakota, although the most common disease in wheat remained tan spot, according to Marcia McMullen, NDSU plant pathologist.

"Loose smut is on the rise in wheat and barley." said McMullen, adding that in loose smut, diseased heads are blackened.

McMullen spoke to a large group of producers at NDSU's "Best of the Best" in wheat and barley workshop earlier this month. The workshop was sponsored by the N.D. Barley Council, N.D. Grain Growers Association and the N.D. Wheat Commission.

In 2009. surveyed fields had 15 percent loose smut with an average incidence of heads infected at 6 percent. By August, there was 19 percent loose smut in post-flowering fields.

"There's nothing to control loose smut beyond seed treatments,". McMullen said.

The fields surveyed were well above the threshold indicating a need for a seed treatment, she added.

According to Roger Ashley, yield losses with loose smut are directly proportional to the percentage of seeds infected, so using seed treatments is a good idea.

NDSU field scouts surveyed more than 1,000 wheat fields and about 280 barley fields across the state by August of 2009.

In 2009, leaf rust was "almost non-existent" and was found in a small number of winter wheat fields.

The cool growing season kept incidences of scab down.

The risk for tan spot in early June, was high all over the state, and was found in about 85 percent of surveyed fields.

It continues to be one of the most I prevalent fungal leaf diseases in the i west because of shorter rotations be-i tweeW wheat crdps, McMullen said.

"Potential yields can be destroyed by tan spot," she said. "It can affect tiller development in the three to five-leaf stage."

She said tan spot can be managed through crop rotations, using resistant varieties and fungicides.

So far, there has been no fungicide resistance found with any of the fungicide chemicals, although there has been some in Europe, she said.

All the early-use fungicide are effective including Tilt. Bumper, PropiMax, Stra-tego, Quadris, Headline, Quilt and the mancozebs.

"There are a lot of choices for early season fungicides and they are all good and have done well on leaf diseases," McMullen said.

Apply at half label full strength at four to five leaf stage in a favorable environment.

"Your best response comes after wheat planted onto wheat stubble with a rainy spring," she added.

Last year, in the west, a 1-bushel response to fungicides was needed for a breakeven price on applying fungicides. In 2009. a 4-5 bushel response was seen in the western region, indicating a good response to fungicides, she said.

In wet weather, fungal leaf spot can happen late at flowering, McMullen said. Pro-ducers should come back with fungicide again at flowering when all heads arc ait and 10 to 15 percent of heads are flowering.

McMullen said there is a concern for finding wheat streak mosaic virus (WSMV) this year. In 2009, 12 percent of fields surveyed showed WSMV.

"There may be plants underneath the snow this spring," she said. "If your spring wheat looks a little yellow, we can test it for, you."

There are no chemicals to control WSMV and the best way to manage it is to control volunteer wheat and grassy weeds in the fall two weeks prior to planting the next susceptible crop. NDSU recommends two weeks to make sure the mite has completed its life cycle, McMullen said. "Don't plant winter wheat too early and don't plant spring wheat too late," she cautioned.

McMullen said they checked on the two-week wait due to producer inquiry with the "experts" in Nebraska and were told two weeks is the right amount of time to wait to plant a new crop into those fields.

Winter wheat planted next to com is not a good idea because the mite can move from the corn to the winter wheat, she said.

For diseases in 2010, McMullen advised producers to watch out especially for fungal leaf spot in the western regions.

"Know your past history, use resistant varieties plus seed treatment," she said. "In addition, use the disease forecasting system. NDAWN forecasts the risk of tan spot and other small grain diseases at http://www.ag.ndsu.nodak.edu/crop disease. According to Ashley, when the risk for tan spot shows six days with "yes," apply a fungicide.

"There are a lot of choices for early season fungicides and they are all good and have done well on leaf diseases. Your best response comes after wheat planted onto wheat stubble with a rainy spring."

Marcia McCullen, NDSU plant pathologist



Copyright 2010 Turtle Mountain Star, Rolla, North Dakota. All Rights Reserved. This content, including derivations, may not be stored or distributed in any manner, disseminated, published, broadcast, rewritten or reproduced without express, written consent from SmallTownPapers, Inc.

© 2010 Turtle Mountain Star Rolla, North Dakota. All Rights Reserved. This content, including derivations, may not be stored or distributed in any manner, disseminated, published, broadcast, rewritten or reproduced without express, written consent from DAS.

More from Turtle Mountain Star