SCALING BACK SCALD
FOLIAR DISEASE NO MATCH FOR NEWLY INTEGRATED GENETICS
BY JEREMY SIMES
The fight against scald is underway for one of Canada’s premier feed varieties.
Aaron Beattie, a barley and oat breeder and the project lead to combat scald resistance at the University of Saskatchewan’s Crop Development Centre, is leading a research project that looks to map several scald-resistant barley genes within CDC Austenson to develop a variety of barley with improved scald resistance.
According to SeCan, CDC Austenson produces grain yields higher than the other two check varieties, Xena and AC Metcalfe.
“Austenson has high yield, plump seeds and good straw strength,” said Jim Downey, research and development manager at SeCan.
Despite Austenson’s strong leaf-disease resistance, it lacks adequate protection against scald, a major foliar disease that affects barley in the wetter areas of the Prairies, especially in Alberta’s southern parkland region.
“Scald is an important disease to look at,” Beattie said, adding that the disease has potential to considerably slash yields. In fact, scald has cut yields in some fields by more than 25 per cent. Currently, average yield losses in Alberta are at 2.4 per cent.
“It’s always been a big issue in parts of Alberta,” Beattie said. “Depending on the year, you might see it in southwest Saskatchewan. However, we saw a lot of it this year near Saskatoon.”
Scald is found on leaf sheathes and leaves. Large, water-soaked, grey-green spots appear on the leaves, which rapidly dry out and become bleached with brown spots. Those spots then engulf the entire leaf and kill it. Subsequently, a decrease in the photosynthetic area on the flag and second leaf reduces seed weight, resulting in yield loss.
If scald appears on the upper leaves and sheathes in mid-July, farmers should expect considerable yield loss. If scald doesn’t appear until early to mid-August, losses from scald will be considerably reduced, as grains are well filled by that time.
To combat the disease, and to ensure the possibility of higher yields for those who plan on growing the new breeding line derived from Austenson, Beattie is mapping three scald-resistant genes in the variety.
Beattie is collaborating with Kelly Turkington, a research scientist with Agriculture and Agri-Food Canada (AAFC) in Lacombe, on this project. Beattie is using one of Turkington’s nurseries to screen the Austenson trials.
Each trial, or test, is restricted to the crop’s lifespan, which is similar to the annual growing season. The data is recorded each July and breeding lines derived from Austenson are established and identified.
“We then characterize that data as to how resistant the barley is to scald,” Turkington said. He ranks the trials based on their scald resistance, and sends them back to Beattie.
“Nothing has surprised me so far,” Beattie said. “Everything is working out as we thought it would.”
Even though the implementation of scald-resistant genes in Austenson will help defend the crop against scald, Turkington said farmers should rotate crops and crop varieties every two to three years to reduce the opportunity for the scald pathogen population to adapt to the new breeding lines.
“If you don’t appropriately manage your field against the scald pathogen population, new scald-resistant varieties may no longer be useful for the farmer and no longer useful for the breeder,” said Turkington.
Downey echoed concerns with scald’s presence on the field.
“Scald pathogen populations change so they can attack certain varieties,” he explained. “We’ve seen some varieties go from resistant to poor because of that. It’s a complex issue.”
But as new disease-resistant lines hit the market, farmers can expect to use fewer fungicides, which would effectively reduce costs and produce an attractive crop to sell, said Barley Council of Canada Chair Brian Otto, who farms in Warner.
“Research like this supports growers’ pocketbooks,” he explained. “It’s good for our bottom line, and better for the environment. We can turn to chemicals, but I’d much rather invest in a seed breeding program. Obviously we need both, but the less fungicides we use, the better.”
The project is slated to finish in 2018.