A new weapon to battle fusarium head blight (FHB) fights fire with fire.
The traditional tools have been agronomy, genetic resistance bred into new cultivars and fungicides — the latter sprayed on wheat and other cereal crops to protect them from the potentially devastating fungus disease that can cut yields and quality.
But a fungus called clonostachys rosea strain ACM941 can also provide FHB protection to cereals, Bill Brown, president and CEO of Adjuvants Plus Inc., told the 8th Canadian Workshop on Fusarium Head Blight Nov. 22.
That strain, and its impact on FHB, was discovered by Agriculture and Agri-Food Canada (AAFC) scientist Allen Xue. Adjuvants Plus Inc., a Canadian firm based in Kingsville, Ont., has the rights to commercialize the biopesticide and is calling it DONguard.
DON is short for deoxynivalenol, the mycotoxin sometimes produced by FHB. When DON levels are high the infected cereal can’t be consumed by people or livestock.
“We are going to register it with a joint (application in Canada and United States) and we hope to submit it in the next couple of weeks,” Brown said in an interview. “In theory it is going to take about 18 months before it is available.”
Although the extent and severity of FHB varies from year to year, it is Western Canada’s worst wheat disease.
FHB is widespread across the Prairies this year and hitting durum wheat especially hard, the Canadian Grain Commission says.
DONguard is an endophyte — a bacterium or, as in this case, a fungus — that lives within a plant for at least part of its life cycle without causing apparent disease. An endophyte fungus can live symbiotically in a plant and defend that plant from harmful fungus.
“All (five clonostachys rosea) prototypes (tested by AAFC) showed significant efficacy for the control of FHB and a reasonable shelf life at 4 C,” AAFC said on its website. “Among them prototype three was numerically superior to the others, reducing the area under the disease progress curve by 82.9 per cent, infected spikelet by 81.9 per cent and fusarium-damaged kernels by 72.7 per cent and increasing wheat yield by 55.7 per cent and 1,000 kernel weight by 26 per cent.”
DONguard controls FHB two ways, Brown said. One is through competitive exclusion.
“Me first, me win,” he said referring to clonostachys rosea getting into the plant before the FHB does, taking its place.
The other is mycopariticism.
“It (DONguard) is kind of like a bear,” Brown said. “You get inside the bear’s cage it looks at you for a while until it is hungry and then it eats you.”
Once in the plant, clonostachys rosea will consume invading FHB, he said.
“It is not a silver bullet, but it is something that really could change the ability to grow quality wheat, barley and oats.”
Research at the University of Manitoba earlier this year showed DONguard reduced the incidences of fusarium-infected wheat kernels as much as the fungicide Caramba, Brown said.
“The year before when it was dry and sunny the results with Caramba were better, but not by a whole lot.”
Brown said DONguard works best under the conditions that favour FHB — warm, with high humidity.
Fungicides work best to protect wheat from FHB when applied just after flowering. DONguard needs to be applied earlier so it has time to grow in the plant, Brown stressed. He recommended applying from the swollen boot stage to the first awns being visible.
Once DONguard is established the plant can be safely sprayed with most fungicides, allowing for extra protection over a longer application window, Brown said.
DONguard is also effective in reducing FHB in seed and is compatible with most seed treatments, he added.
FHB-infected crops can also be treated with DONguard to cut DON levels post-harvest.
“That is what we are working on next,” Brown said. “We can really clean up the crop. The goal will be to improve the grade. If we can remove one ppm to less than a half-part per million for barley, we are a hero. That is a religious issue for beer drinkers, right? It is important to have high-quality barley for beer.”
Brown suggests DONguard be used throughout the production cycle.
“Inoculate the seed before planting, inoculate the foliage, (and) reduce the perithecial state (the spore fruiting bodies in cereal residue, post-harvest, which cause future infection),” he said.
Preventing FHB from colonizing cereal residue and a source of future infection is one of DONguard’s strengths, one scientist attending the meeting said.
While DONguard has potential, the scientist, speaking on background, said the product has a long way to go before being used by farmers.
As Brown acknowledged, DONguard’s efficacy can be hurt by ultraviolet light. The company is working to mitigate that, he said.
DONguard is a living organism and must be kept cool.
“So when we ship it to the Prairies it will go in a warehouse,” Brown said. “So long as it is cool in advance it’s not a problem because it is going to be sprayed in June or early July.
“It will last months. The key is to get it on at the right time.
“When we pre-treat seed it survives in the seed for years.”