Pearce: Stripe rust in winter wheat is Ontario’s biggest threat

Normally, stripe rust in winter wheat isn’t a huge problem for growers in Eastern Canada, and particularly in Ontario — at least, not at this stage of the growing season — but the 2016 growing season isn’t shaping up to be “normal” either.

For now, the immediate challenge before growers is to get out and scout their wheat fields. According to Dale Cowan, senior agronomist with Agris Co-operative, the worst-hit region for stripe rust at week’s end is west of Thamesville in Chatham-Kent, south of Highway 401 and down along the Lake Erie shoreline into Essex County.

This is the region, Cowan said, where the rust spores were first blown in and deposited, and where the disease is most advanced.

But there have been additional sightings farther north, even into Grey and Bruce counties. And no matter where it’s found, growers need to act quickly to avoid significant losses in yield.

“It’s at the point where you want to keep the flag leaf clean because it produces 70 per cent of the yield, and it’s sporulating very quickly and moving very fast,” said Cowan.

“The next stage we’d consider a fungicide would be T3 (head stage), so what we’re advising is that you have to keep the flag leaf clean with a T2 (flag leaf) fungicide.”

The problem began farther south in the U.S. — and Cowan noted it was already 400 miles further north into Kentucky than it normally should have been.

Even for a grower with crops three days away from a head spray (at T3, growth stages 59 to 65), the disease is advancing so quickly that waiting those three days to save money could cost him or her 50 per cent of a field.

In the past three days, Twitter has seen a variety of photos depicting the extent of the spread of the disease. One individual photographed his lower legs and boot tops covered in yellow-orange spores, just from walking through a field. Another shows the soil between rows with the same yellow-orange colouration.

“Once the flag leaf is gone, you’re going to take a 50 to 60 per cent yield hit,” said Cowan. “If you don’t spray the flag leaf now and you’re going to wait for T3, there’ll be nothing worth protecting even three or four days from now. If you’re a week away from heading, you have to make two passes through the field or you just won’t have anything worth spraying at T3.”

The fungicides a grower would use for T1 (tiller) or T2 (flag leaf) cannot be used if the awns are showing or the heads emerging, Cowan warned. Those particular fungicides carry a strobilurin, which will increase levels of deoxynivalenol (DON) — and the risk of DON infection is extremely high, as well.

“We have this situation where we have rust, where we can lose half our yield, or DON, which will make the crop unsalable,” Cowan said, adding that neither is a great option.

“Those are your two choices, so you can’t just sit there and ignore this crop because you won’t have a wheat crop if you’re badly infected. And the first step is you have to get out and scout your fields!”

Ralph Pearce is a field editor for Country Guide at St. Marys, Ont. Follow him at @arpee_ag on Twitter.

(Photo courtesy OMAFRA)
U.S. researchers have come up with a new method of estimating crop yields from small farms in Africa using high-resolution images from the latest generation of satellites – a development which could help cut hunger in poor parts of the world. Improving agricultural productivity is one of the main ways to lift people out of poverty but without accurate data it’s difficult to identify the farmers who need help, scientists from Stanford University said. Images from new, inexpensive satellites could be used to estimate yields and test interventions in poor regions where data is scarce, they said in a paper published in the Proceedings of the National Academy of Sciences Feb. 13. “Improving agricultural productivity is going to be one of the main ways to reduce hunger and improve livelihoods in poor parts of the world,” said Marshall Burke, an assistant professor at Stanford’s School of Earth, Energy & Environmental Sciences. “But to improve agricultural productivity, we first have to measure it, and unfortunately this isn’t done on most farms around the world,” he said in a statement. While Earth-observing satellites have been around for more than three decades, most of their images haven’t been detailed enough to show the small agricultural fields common in developing countries. But with satellites becoming cheaper and offering improved image resolution, it is now possible to capture very small areas, the researchers said. David Lobell, an associate professor at the school, said in a video that satellites which were once the size of school buses were now the size of fridges or even shoeboxes. “You can get lots of them up there, all capturing very small parts of the land surface at very high resolution,” added Lobell, who co-authored the study. “Any one satellite doesn’t give you very much information, but the constellation of them actually means that you’re covering most of the world at very high resolution and at very low cost. “That’s something we never really had even a few years ago.” The researchers focused on Western Kenya, where smallholders farm maize or corn on small half-acre or one-acre plots, to test if images from the new satellites were detailed enough to provide reliable estimates of crop yields. “Just combining the imagery with computer-based crop models allows us to make surprisingly accurate predictions...” Burke said. The researchers plan to scale up their project across sub-Saharan Africa.

 

About the author

Glacier FarmMedia Feed

GFM Network News

Glacier FarmMedia, a division of Glacier Media, is Canada's largest publisher of agricultural news in print and online.

GFM Network News's recent articles

explore

Stories from our other publications