The question is “when” not “if ” Ug99, a potentially devastating wheat stem rust discovered in Uganda in 1999, will reach Canada, says Winnipeg-based Agriculture and Agri-Food Canada plant pathologist Tom Fetch.
Eighty-five per cent of Canadian spring wheat varieties are vulnerable to this new race of fungus disease, so the longer Ug99 stays away the more time researchers have to develop new resistant wheats, Fetch told the Manitoba Seed Growers’ Association’s 2009 Genetic Expo in Winnipeg Dec. 9.
“If it (Ug99) gets it (wheat) early enough, it takes everything,” Fetch said.
“We think it’s going to get here, when we don’t know, but we’re trying to prepare. We want to be ready before it gets here.”
AC Cadillac and Peace are two Canadian spring wheats resistant to Ug99, but neither is popular with western farmers.
Wheat breeders are making crosses with Cadillac and Peace and should have new Ug99-resistant varieties in a couple years, Fetch said. The bad news is that the resistance is based on just one gene.
“So we’re really not hanging on much here in Canada,” he said.
“We know that’s not enough. It’s a start – better than nothing. We know we need to do better.”
Meanwhile, Ug99 (race TTKS) is on the move. It was detected in Kenya in 2001 and Ethiopia in 2003. In 2006 a new race, TTKSK, was found in Sudan and Yemen.
Two other variants, TTTSK and TTKSK, have also been found in Kenya, considered a “hot spot” for stem rust because of an abundance of indigenous barberry bushes, an alternate host, allowing
the fungus to reproduce sexually resulting in new races.
Once the disease crosses the Red Sea wheat in Pakistan and India will become infected. That’s what happened 10 years ago with Stripe rust.
Some believe Ug99 is already in Pakistan. Fetch said he’s running tests to find out. Once in Pakistan, the next stop is China.
“If it gets into China that’s one step away from coming to us and I am afraid if it gets into China it’s going to cause some big problems there,” he said.
Ug99 will come to North America one of two ways – on the wind or on people, Fetch said. Winds will take spores into China and across the Pacific Ocean to us. Wind may also blow the disease into Morocco, and then hurricanes will bring it to South America or directly to Mexico and the United States.
The other possibility, which Fetch described as more unpredictable and dangerous, is for a traveller to bring the spores into Canada. That’s happened several times in Australia, he said.
Fungicides will control Ug99, but developing resistant varieties will save farmers money, Fetch said. That’s the preferred option for most farmers in the developing world, where few can afford chemical treatments.
Fetch estimates 90 per cent of the world’s wheat varieties are susceptible to Ug99. Not only are farmers’ livelihoods at risk, but also lives should world wheat supplies drop dramatically. That’s what prompted the late Norman Borlaug, father of the “Green Revolution” and Nobel laureate, to help launch the Global Rust Initiative in 2004.
The Bill and Melinda Gates Foundation has donated $26.8 million to fight Ug99. Agriculture Canada has invested $13 million to help Fetch find resistant genes wheat breeders need to protect new varieties.
According to a release from Cornell University, which is administering the Gates foundation money, Africa imports about nine million tons of wheat a year (more than 80 per cent of its needs) and the gap is expected to increase.
Meanwhile, wheat production in India, where the Green Revolution boosted production sixfold between 1965 and 2000, has been dropping.
“Using a very conservative estimate of 10 per cent loss in regions hit by Ug99, annual global losses by the year 2016 are predicted at 25 million tons (equivalent to about $8.3 billion at today’s prices),” Cornell University says. “Our largest target market is the 50 million farming families in the Indo-Gangetic plain who rely on wheat production, who stand to lose over seven million tons of annual production ($2.3 billion) for each 10 per cent drop in yield.”
More frightening, however, is the potential for even bigger losses.
“Between Rabat and Vladivostok, there are over 100 million hectares of wheat under cultivation, all genetically susceptible to Ug99.”
Canadian and American farmers were ravaged by stem rust during the early years of the last century. That prompted the Canadian government to create the Dominion Rust Laboratory at the University of Manitoba in 1926. Canada hasn’t experienced a major outbreak of stem rust since 1955.
Success led to complacency. In 2000, Agriculture Canada almost scrapped its stem rust research.
“From what I was told he (my predecessor Don Harder) really had to go to bat and say ‘you don’t want this program to get cut,’” Fetch said. “You need to watch this thing because there can be a problem.”
Stem rust is considered the most dangerous of rusts because it attacks the stem, which moves nutrients into the plants and because often infected plants break putting the crop on the ground.
“One acre of wheat with moderate rust can produce something like 10 trillion spores in a day,” Fetch said. “So if you get some rust going in a field it doesn’t take long and you’ve got a big, big, big problem.”
WHEAT AT RISK: Agriculture and Agri-Food Canada plant pathologist
Tom Fetch tested Canadian spring wheat in Njoro, Kenya to assess its susceptibility to stem rust Ug99. Most Canadian wheats are susceptible
such asAC Superb (l). Several varieties such as Peace, are resistant, however, Peace is not popular with Canadian farmers.