Keep eye out for stripe rust, says pathologist

Stripe rust continues to lurk in Alberta winter wheat, and crop pathologists are urging scouting for the fungal disease now that spring cereals are emerging.

Rust has been reported in crops in most counties and municipal districts in eastern Alberta south of Edmonton.

It was first noticed in the province near the end of April. Last week brought the first reports that it is moving into upper leaves in some crops, said Alberta Agriculture plant pathologist Michael Harding.

“It’s important to be scouting when you’re out in the field and looking to see if it is moving up onto the new leaves.

“For the most part, the reports have still kind of been old infections on lower leaves.”

Lower leaf infections indicate stripe rust overwintered in fields rather than arriving on the wind from the Pacific Northwest.

Spraying is not a likely consideration unless the disease affects the flag leaf and upper canopy, and crops are some weeks away from that stage.

Stripe rust thrives in cool, wet weather of the type that affected Alberta last weekend. However, hotter weather in the forecast could reduce its ability to spread.

The disease does not colonize as quickly in hot, dry conditions and in addition, genes in resistant cereal varieties are activated at higher temperatures, protecting the plants.

The counties of Forty Mile, Parkland, Cardston, Lethbridge, Warner and Mountain View have all reported occurrences of stripe rust this year, as has the Municipal District of Taber.

barb.glen@producer.com

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