Stripe rust observed on annual wheat tour, recent rain too late for parts of Colorado

Candace Krebs
The Ag Journal
Stripe rust appears on a leaf sample seen in Smith County, Kansas, and posted on Twitter by K-State small grains specialist Romulo Lollato, one of 45 participants on this year’s Wheat Quality Council Hard Red Winter Wheat Tour. A period of wetter weather is increasing the incidence of foliar disease within the crop.

Much needed moisture is coming too late for drought-stricken wheat in parts of Colorado, but farmers who still have good crop prospects are on heightened alert for foliar diseases after a week-long stint of rainy weather.

Crop scouts attending the Wheat Quality Council Hard Red Winter Wheat Tour discussed those and other developments at the first stop of a three-day swing through Kansas and surrounding states Tuesday evening.

The tour concludes Thursday in Manhattan.

Sarah Ahrens, promotion coordinator for Nebraska Wheat, reported that stripe rust has migrated north into her state, even though overall subsoil moisture levels remain drier than normal.

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Many of the 45 scouts on the tour confirmed seeing aerial applicators busy applying fungicides as they trekked from east to west across the northern portion of the state.

Before the tour kicked off, Kansas State University wheat specialists shared a graph showing the top yield-robbing diseases for the 2020 season. Stripe rust and leaf rust, which led the pack, are likely to be factors again this year.

Agronomists say rust can knock back yields by 15-20%.

Other top diseases on last year’s list were fusarium head blight, tan spot, septoria complex, wheat streak mosaic and bunt or loose smut, followed by barley yellow dwarf virus.

Reporting at the stop in Colby, Jeanie Falk Jones, an area crop specialist with K-State, said stripe rust pressure had been limited so far, and many farmers were still debating whether fungicides and herbicides would be needed.

“As far as wheat streak mosaic, we’re seeing a little bit in spots, but it’s not widespread,” she said.

The wetter weather pattern could change the disease and weed equation going forward, she noted.

“Two weeks ago, we were starting to see drought stress showing up, but the moisture in the last two weeks has helped alleviate some of that,” she said.

She attributed a large number of uneven stands across the area to a lack of available moisture at drilling time and the impact of various farming practices on moisture levels.

“We saw more earlier planting this year because that’s when we had moisture,” added Lucas Haag, K-State’s northwest area agronomist. “Most of the wheat went in seven to 10 days earlier than normal, with good reason, because we did run out of moisture later.”

Both specialists told scouts they would see considerably tougher conditions heading south the following day.

Nowhere has the drought’s impact been more evident than in Colorado.

While Colorado officials were not at the reporting session Tuesday night, they did provide written remarks, part of which were read aloud by Aaron Harries, vice president of research and operations for Kansas Wheat.

Colorado officials reported recent rains were too late to do any good in many parts of the state, with abandonment rates ranging as high as 65% in Kiowa County.

They added that conditions gradually improve moving to the northeast, where yields could end up being around average.

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National Ag Statistics Service predicted the state’s crop would average 37.3 bushels to the acre, but independent crop scouts were a little more pessimistic, pegging the likely average at 34 bushels.

Generally speaking, disease pressure has been low, with no wheat stem sawfly observed so far. Some locations south of Interstate 70 did show Russian wheat aphid damage, although at most locations, infestation levels were below treatment levels.

Colorado producers will have a chance to learn more about the Colorado crop when the annual Colorado wheat field days return in-person this year, June 10-16, at 11 different variety trial sites across the Eastern Plains. Akron will not host a tour this year.

The full schedule is posted at the Colorado Wheat website, ColoradoWheat.org.