Evidence of the widening spread of fusarium head blight acrossSaskatchewan this year adds to a growing chorus emphasizing the importance of variety choice in keeping the disease at bay.
However, industry officials warn there is no perfect solution for growers.
“You’re going to deal with whatever is the biggest issue in your region,” said Pierre Hucl of the University of Saskatchewan’s Crop Development Centre, noting the best varieties for wheat midge and sawfly resistance aren’t the best to fight fusarium.
“This year, I suspect fusarium spread out across a much wider swath than we’ve seen before into areas where it wasn’t seen before.… The picture is going to change as to how people pick varieties, I suspect.”
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Warm and humid weather in July saw parts of central Saskatchewan look more like Manitoba, where producers have a longer history with the disease, said Grant McLean of Saskatchewan Agriculture.
Producers in the Saskatoon and Melfort areas may not have been expecting to make a fungicide application to protect their wheat from fusarium, which damages yields, kernel size and grading scores and produces mycotoxins such as DON.
“I’m expecting to have some unhappy stories come out because there are some varieties that are pretty susceptible and they might’ve gotten in trouble,” said Stephen Fox, a spring wheat breeder with Agriculture Canada.
“It’s an area where they’re not used to dealing with fusarium.”
The upcoming harvest survey from the Canadian Grain Commission will provide growers and officials with a better idea of the disease’s distribution and damage in 2012, he said.
The disease certainly isn’t new to the province: it’s been a concern in parts of the Prairies for almost 30 years. As well, researchers are aware of a new, more aggressive strain of the disease that has been moving west over the last decade.
It is a priority for breeders and new varieties are coming through the pipeline, but resistance remains a complicated trait to select for on the Prairies. Hucl said it’s the same in other wheat growing parts of the world, meaning improvements are slow to materialize.
A list of wheat varieties shows only a few with moderate resistance characteristics, such as Carberry or Cardale in the western red spring class.
Fox has developed the Cardale variety, which is not yet available.
“It’s better than the ones that I’ve released before,” he said.
“It has two known genes for fusarium head blight resistance and so that’s part of the reason why it’s doing a little bit better.”
It was bred with southern Manitoba in mind and yields similar to McKenzie but below the high-performance Unity.
However, the semi-dwarf strong-strawed wheat doesn’t have midge resistance.
“I think we’re going to have things that are better than what we have currently, but we’re never going to have a variety that’s immune to fusarium,” said Hucl.
A recently published report from Nora Foroud, a molecular biologist with Agriculture Canada in Lethbridge, studied the performance of several varieties and double haploid lines when exposed to the more aggressive strain of fusarium. In the greenhouse study, which was published in the journal Plant Disease, the more susceptible varieties saw the greatest accumulation of DON.
The findings demonstrate the importance of growing highly resistant wheat cultivars, Foroud said.
“We are continuing in using the double haploid production using the (fusarium graminearum trichothecene) selection to select for high levels of resistance,” she said.
“One of the things that this study that we recently published shows is that this method is successful in incorporating high levels of resistance and so we hope to take it to the next level and bring in good agronomic and end-use properties.”
Winter wheat is less susceptible to fusarium than spring varieties because of when it flowers. The crop is one strategy for producers looking to mitigate the disease, as are earlier seeding dates, but a multi-pronged approach, with crop rotations and fungicide applications, is recommended.
“Studies have shown that an integrated approach is much better than using one of those options alone, but that being said, resistance is the most important factor,” said Foroud.
“If you don’t have resistance, then the effects of crop rotation and fungicide under high disease pressure becomes almost irrelevant.”
