Kansas wheat breaks dormancy and fields begin to green up, a Kansas State University plant disease expert is urging growers to keep a close eye on a familiar set of threats: wheat rusts.

Wheat pathologist Kelsey Andersen Onofre said spring marks a critical window for monitoring stripe rust, leaf rust and stem rust — three diseases that can significantly affect yield if conditions favor their development.

“This is the time of year when we start to think about wheat rusts,” Andersen Onofre said. “We’re coming out of dormancy, and this is when we really start watching not only what’s going on in Kansas, but what’s happening in the states to our south.”

Stripe rust has been the most common wheat rust in Kansas in recent years. The disease is easily identified by its bright orange spores that form distinct stripes along the veins of wheat leaves.

“That’s the rust that looks like orange Cheeto dust in stripes on our wheat leaves,” Andersen Onofre said. “If you run your finger along the leaf, it comes off on your fingers and turns them orange.”

Despite its prevalence in past seasons, Andersen Onofre said the outlook for stripe rust is lower this year, largely due to unfavorable conditions in Texas, where the disease often begins its northward movement.

Wheat rusts typically do not survive Kansas winters, instead migrating north each year from southern regions such as Texas or even Mexico. Monitoring disease pressure in those areas can provide an early indication of what Kansas producers might expect.

“We’ll see the pressure in Texas in February and in Oklahoma this time of year, and that gives us a pretty good indicator of what we’re going to expect here in Kansas,” she said.

So far, stripe rust activity in Texas has remained low. However, leaf rust — another common disease — has been more active there and could pose a greater risk if weather conditions shift.

Leaf rust tends to appear later in the growing season and prefers warmer temperatures. Unlike stripe rust, its orange to brown spores are scattered across the leaf rather than forming stripes.

“It seems like leaf rust will potentially be a higher risk for our crop than stripe rust this year,” Andersen Onofre said.

That risk could increase if Kansas experiences wetter weather in April, which would favor disease development and spread.

Adding to the concern is the presence of leaf rust in some Kansas fields last fall. While most of that infection likely did not survive the winter, Andersen Onofre said there is a small chance it persisted under snow cover or dense crop canopies.

“If you had leaf rust active in your field in the fall, those are important fields to start scouting again this spring,” she said.

Early detection is key. Andersen Onofre recommends that producers regularly scout fields and use wheat variety ratings to determine whether fungicide applications are warranted.

“If it starts to get going again, especially if we have some wetter weather, that would be the time to think about a fungicide application,” she said.

Leaf rust can cause substantial yield losses if left unmanaged. Andersen Onofre noted that when about 5% of a field shows infection, growers should consider treatment. In severe cases, losses can reach 20%.

Stem rust, the third major wheat rust, remains relatively rare in Kansas and typically appears late in the season. It primarily affects susceptible varieties and is identified by darker brown spores forming along the plant’s stem.

While stem rust is less common, Andersen Onofre said it still warrants attention as part of an overall disease management strategy.

Ultimately, she emphasized that staying informed and proactive is the best defense.

“Scouting and knowing your varieties are really your first line of defense,” Andersen Onofre said. “That’s what helps guide those management decisions throughout the season.”

More information on Kansas crop conditions is available from local K-State Extension offices in Kansas.

***