Southern Alberta farmers and their neighbours to the south were both hit with wheat stripe rust last year, and a Montana State University plant pathology specialist says it’s time to get prepared for it again this season.
Speaking to the recent Farming Smarter conference in Lethbridge, Dr. Mary Burrows delivered a message to which producers paid rapt attention.
“I know stripe rust is going to be an issue in Alberta next year,” she said. “So you need to scout your fields and if you see it and you have a susceptible variety, you need to consider a fungicide application. If you have a resistant variety, you do not.”
Burrows described “a perfect storm” of conditions ripe for the fungus to reappear.
“We had widespread fall infection last fall, we had a very extended fall so it was warm, we had a lot of early-planted winter wheat, we had favourable spring temperatures and not only moisture, but flooding that kept the humidity high throughout the state for the majority of the year,” Burrows said.
“In areas where I do not normally see stripe rust, it was very, very severe.”
The epidemic was also more severe because of new strains which have overcome varietal resistance. Burrows said the new strains can replicate at higher temperatures and overwinter better as well.
She stressed the best proactive measure is to plant resistant varieties, but fungicides were used successfully once disease was identified in the fields.
“Fungicides were used very extensively in (Montana) and were quite effective. Any time I sprayed a susceptible variety, I got about a 10-bushel yield increase, so if you have a susceptible variety and you have stripe rust, you need to spray. If you have a resistant variety I do not recommend spraying at all because anytime I sprayed I did not get any yield response,” Burrows said.
Timing of the fungicide application is critical. “We had quite a bit of late-applied fungicides, what we call ‘rescue spraying,’ and what I want you to take home is if it’s past flowering, you don’t want to spray because your economic return is going to be much less.”
In some instances, it took only four days for a field showing the first signs of disease to turn completely yellow, and Burrows advised producers to keep a watchful eye on the situation this season.
“This emphasizes the importance of getting into your fields as often as you can and looking at the wheat, getting out of the truck and picking up some plants and if you see something, ask some questions.”