Stripe Rust Found. Be on the Lookout.

Sad to say but the UW Field Crops Pathology Team observed the first signs of stripe rust for the 2017 field season near Sharon, Wisconsin in a Winter Wheat variety trial plot.

The Team thinks that the pathogen that causes this blight overwintered on wheat leaves that remained green through the winter of 2016/17.

To the Team’s knowledge, this is “the first time that overwintering of the stripe rust fungus has been observed in Wisconsin winter wheat fields and is likely due to the mild winter season.”

Stripe rust is caused by the fungus Puccina striiformis. It’s identified  by “orange/yellow pustules that typically occur in a striped pattern on the surface of the wheat leaf.”

In cases of low severity of infection, you might see single or sparsely spaced pustules.

The recommended management plan is first to use resistant cultivars. If the stripe rust still remains, appropriate fungicides becomes the next step.

While the window for choosing cultivars is  closed, scout aggressively—especially in fields where you planted a susceptible cultivar. The possibility for a stripe rust epidemic calls for frequent and careful scouting.

If you spot stripe rust pustules, please consider sending samples to the University of Wisconsin Plant Disease Diagnostic Clinic for positive identification.

While it is typically too early to apply fungicide at this growth stage, you may need to this season if strip rust infects your wheat stand. That’s why frequent and careful field scouting—and positive confirmation of a stripe rust infection—are so important.

Should you need products to control stripe rust, turn to publication A3646—Pest Management in Wisconsin Field Crops. There are many fungicides labeled with superior efficacy on stripe rust. You should be able to find an excellent-rated product that also fits your budget.

And please remember to stick to the labeled rates.

But for now, our best advice is to get out in your fields and scout!

Stripe rust fungus under a microscope

Urediniospores of the stripe rust fungus. The red arrow shows a germinating, viable spore.

pustule of stripe rust

A single pustule of the stripe rust fungus on a wheat leaf.

stripe rust low incidence

Low incidence and severity of stripe rust on winter wheat. Scout carefully.