Fungal infection threatens local wheat crops

A plant pathologist for the province says he's never seen a case of stripe rust like the one found in winter wheat at an Olds cereal nursery.

“This is the first report of the disease overwintering in the last decade or two. The first report I've ever heard of the disease overwintering in that area around Olds,” said Michael Harding, plant pathologist for Alberta Agriculture and Rural Development.

“So the situation that's occurring in Olds is very unique and maybe the first time.”

Stripe rust is a disease caused by a fungus that affects cereals like wheat, barley and certain grasses. Symptoms include the appearance of yellow stripes that run parallel to the veins of leaves.

The leaves' epidermis then breaks open, revealing the orange fungus spores.

Two Alberta Agriculture and Rural Development plant pathologists discovered the disease near Olds on June 2.

Stripe rust was also reported near Lacombe and Bentley.

According to Harding, there's a chance that the disease could cause significant crop losses, especially among those that do not have genetic resistance.

“In an unprotected susceptible crop, stripe rust could wipe it out. It has the capability to cause devastating economic loss to a cereal crop,” he said.

Harding is urging farmers to examine their fields and spray fungicide if they find the disease.

“Even if you have a resistant cultivar, you still need to scout your field to make sure the resistance is holding back the disease,” he said.

That's because genetic resistance can depend on specific environmental conditions. For example, some plants can only withstand the disease as adults and only in high temperatures, he explained.

Farmers unsure if they have GMO (genetically modified organism) crops resistant to stripe rust should check the Alberta Seed Guide online, he added.

This occurrence of stripe rust was found in winter wheat, which is seeded in the fall and grows in the spring. During the winter, the pathogen lies dormant before activating in the spring.

“So that's what's happened in Olds. On some winter wheat crops there was likely some stripe rust that overwintered in a latent form in the host and in the spring when the crop began to grow again, the full-blown disease became present again,” he said.

The fact that the disease is infectious adds to the problem, Harding continued.

“The concern with that is, early stripe rust infections, early in the season like this can move into the spring seeded cereal crops and the earlier that the disease comes in, the more problematic it can be and more damage can be caused,” he said.

Stripe rust is a yearly occurrence in southern Alberta each year. It arrives to the province because the disease is well adapted for aerial travel, mostly from the Pacific Northwest or southern U.S., Harding said.

However, he's not ready to declare this case an epidemic, saying that hot, dry weather can contain the disease.