Disease monitoring | Wheat growers urged to select varieties that carry resistance to disease
A report of stripe rust near Olds, Alta., is likely disease that overwintered rather than a sign of a 2014 outbreak.
Agriculture Canada research scientist Denis Gaudet told a group assembled for a June 12 Farming Smarter crop walk that only one area of the province has reported stripe rust this year. No sign of the crop disease has shown up in field scouting elsewhere.
Stripe rust did enter Alberta last year but wasn’t the major problem experienced two or three years ago, said Gaudet.
That was when a different race of inoculum in the U.S. Pacific Northwest blew into Alberta. It overcame the resistant gene in Radiant, a popular winter wheat variety, and then spread into spring wheat.
Read Also
Ag In Motion 2025 site hub of activity
day before Ag in Motion preview.
“That is where we’re at right now,” said Gaudet.
“The good news is that newer varieties of winter wheat are resistant to stripe rust. Rob Graf, our winter wheat breeder, has been really on top of this problem, has made really good progress.
“Right now we still have a fair number of susceptible varieties around on the winter wheat side. On the spring wheat side, there’s good resistance in a lot of our varieties for stripe rust.”
Gaudet advised wheat growers to consider stripe rust resistance when making planting decisions because its potential for infecting crops in any given year is hard to predict.
He also advised against preventive fungicide spraying because the investment may not be worth it. Frequent scouting is the only way to gauge a stripe rust problem.
If spores do arrive, there is a 20-day lag time between the spore shower and infection, said Gaudet.
“If you don’t see any pustules in your field, it’s unlikely that you’re going to see a massive outbreak in that field.”
However, spraying may be warranted if stripe rust does appear, and it’s a susceptible variety, especially if it is early in the growing season.
Researchers have been studying the timing of fungicide applications on three varieties to determine what is optimum: Lillian, a resistant variety; CDC Imagine, which has an intermediate level of resistance; and Barrie, which is susceptible.
Gaudet said two years of study have found that there is no effect on yield and quality when spraying Lillian for stripe rust. However, there is a beneficial effect from spraying Barrie.
Growers who see the need to spray should do so just before flowering.
He also said it may not be worth spraying for leaf spot and tan spot should they be found in wheat fields.
“We’re really unsure what impact leaf spots have on yield. Most of our wheat varieties do not warrant control of leaf spot,” he said.
“If you’re going to consider spraying for something like leaf spots, we’re really unsure if you’re going to recover that investment on that spray.”
