Stripe rust alert for Alberta wheat producers

Read the blog posts from Prairie Crop Disease Monitoring Network:

• Stripe rust alert for southern Alberta – July 10th
• Stripe rust now in central Alberta and additional reports from Manitoba – July 12th

On July 9th, 2024, stripe rust was found in a winter wheat field planted with AAC Wildfire in Warner County. Stripe rust levels were low to moderate depending on the area of the field visited.

Only a few days later, on July 12th, stripe rust was reported from a field of CDC Pilar wheat in Lacombe county. Stripe rust has made an appearance in commercial fields in south-central Manitoba, south-central Saskatchewan and southern Alberta from late June to early July.

South to Central Alberta has seen an increased number of wind trajectories that could have carried stripe rust spores from the Pacific Northwest (mainly Washington, Oregon and Idaho). Growers in south to central Alberta are encouraged to actively scout wheat fields for stripe rust symptoms as timely fungicide applications may be needed.

Fungicide application for stripe rust is recommended when the % of plants infected or the area of leaf infection approaches 5%. Yield impacts are typically higher when stripe rust arrives before head emergence, although yield losses can still be problematic after head emergence, especially with more susceptible varieties.

The rust pathogen is host specific, meaning the “special forms” that infect wheat and barley are different. Puccinia striiformis f. sp. tritici causes stripe rust in wheat, while Puccinia striiformis f. sp. hordei causes stripe rust in barley. Currently, barley varieties’ resistance to stripe rust is available in Alberta Seed Guide. However, if risk is present, fungicide strategy for barley stripe rust is similar to wheat. 

Resources available to help you stay on top of stripe rust:

• PCDMN rust risk reports: rust risk maps & wind trajectories (Figure 1 below)
• PCDMN In-Season Updates: blog posts regarding disease observations & risks
• Alberta Bluebook: find the registered fungicide products effective in managing stripe rust
• Alberta Seed Guide: find out how susceptible your variety is to stripe rust
• Boots on the ground! Scout for stripe rust symptoms and apply a fungicide when close to 5% of the leaf area is infected.

Figure 1. Stripe rust symptoms on the east side of a winter wheat field, Warner County, July 9, 2024. Picture courtesy of Scott Knutt, SJK Agronomy, Lethbridge, AB.

Figure 2. Total number of reverse trajectories, indicating the risks of rust spores carried by wind. Picture source: Prairie Crop Disease Monitoring Network.