Archives

Researchers winning battle with barley yellow dwarf virus

Western Canadian crop researchers are coming to grips with the barley yellow dwarf virus (BYDV), the number one viral threat to small-grain cereal crops in Canada and world-wide.

Advances in breeding and other research have led to the development of wheat and barley lines with improved tolerance and resistance to the disease, says Dr. Steve Haber, a cereal virologist at Agriculture and Agri-food Canada’s (AAFC) Cereal Research Centre in Winnipeg. AC Superb wheat is one of several new cereal varieties with greater BYDV tolerance already in producer’s hands, and a two-row barley in advanced breeding stages is set to emerge as the first highly resistant line.

“We’ve made significant progress over the past decade, and we can build on that to develop more varieties with better performance against the barley yellow dwarf virus,” says Haber.

There are no chemical controls for BYDV and researchers view developing improved cereal genetics as the most effective and sustainable long-term control. This research effort at AAFC and the University of Saskatchewan Crop Development Centre is supported in part by farmers through the Wheat and Barley Check-off Fund, administered by Western Grains Research Foundation.

The BYDV strikes infrequently on the Canadian prairies but epidemics can cause up to 80 percent yield loss, says Haber. Crops are infected with the virus by cereal aphids from the U.S. that are carried north by low level air currents. Oats are the hardest hit by the virus, followed by barley and wheat.

“The aphids do no overwinter in Western Canada and the virus is not transmitted by seed or soil, so the virus strikes more sporadically here than it does in other parts of the world,” says Haber. “But if it hits crops that are at an early growth stage, it can cause severe damage to yield and grain quality,”

All commercial barley varieties, as well as most wheat varieties, are susceptible to the virus, says Haber. But researchers are making progress by testing crop lines early in the breeding process and incorporating new sources of genetic tolerance and resistance.

Barley breeding programs have identified both tolerant and highly resistant germplasm, which are set to emerge in the form of new varieties over the next several years, he says. The most promising example is an advanced two-row malt barley line at AAFC’s Brandon Research Centre that has high BYDV resistance.

“The challenge has been to combine tolerance or resistance into a complete package with other desirable quality and agronomic attributes,” says Haber. “But this challenge is being overcome.”

Resistance has been hard to come by in wheat, but several varieties have already been developed with good tolerance to the disease, he says. One example is AC Superb, a high-yielding Canada Western Red Spring wheat variety developed at the Cereal Research Centre. Tolerant varieties can still become infected by the BYDV, but the potential for damage is far less than it is with susceptible varieties.

“We have found that many varieties and advanced lines of wheat have partial degrees of tolerance,” says Haber. “By making the right choices of parents and selecting under repeated generations and disease pressure, we’ve found it is possible to select lines that are better than either of the parents contributing partial tolerances.”

Basic research in the U.S. and Australia may also yield more knowledge about the disease and sources of resistance that could pay off for Canadian producers in the future, he says.

Until more barley and wheat varieties with better BYDV performance hit commercial channels, farmers should ensure they plant their crops at the right time, he says. Winter cereals planted early and spring cereals planted late have increased chances of falling victim to the virus.

“It’s also important to not misdiagnose the problem,” he says. “Often, damage caused from the virus is mistaken for nitrogen deficiency, and to place more nitrogen on in future years when that isn’t the problem is useless and costly. If you see a long, yellow strip in a field, it’s probably not BYDV. But if you see it in circular patches in a field, that’s a clue that it’s the virus.”

Western Grains Research Foundation’s Wheat and Barley Check-off Fund contributes over $3.6 million annually to wheat and barley breeding programs in Western Canada.

WGRF information at www.westerngrains.com

© 2002 Meristem Land and Science
Meristem® is a registered trademark of Meristem Information Resources Ltd. All rights reserved.
Legal Disclaimer