Heat treating grain could soften the blow of fusarium head blight on
the Prairies.
Agriculture Canada research scientists have been testing the effects of
heat treatments for two years. The research shows the treatments can
virtually eliminate all fusarium pathogens from infected seed.
That could prove valuable to the eastern Prairies, which are struggling
with fusarium head blight and could lose critical markets for grain
unless more ways are found to cope with the cereal crop disease.
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The research could also benefit Alberta cattle feeders, who
traditionally import a lot of feed grain from the eastern Prairies.
As well, it could help organic farmers, who aren’t allowed to use
chemical fungicides.
Among the pathogens killed by the heat treatment are those caused by
Fusarium graminearum, the species of fusarium most devastating to
cereal crops in Manitoba and eastern Saskatchewan during the past
decade.
“The heat treatment can be quite effective,” said Jeannie Gilbert, a
research scientist and plant pathologist at Agriculture Canada’s Cereal
Research Centre in Winnipeg.
“We have certainly seen some effect there. Levels of fungal survival
were reduced to less than one percent in some treatments.”
The research centre applied heat treatments to wheat seed during both
years of the trials. Barley was included this year. The research
encompassed both healthy and infected seed.
A range of temperatures was used on infected seed for different lengths
of time. A treatment at 70 C over the course of five, 10 or 12 days
proved to be most effective.
At 90 C, the seed was essentially killed.
“It seemed to be too hot a treatment,” Gilbert said. “We got very low
emergence from that seed.”
While the findings are encouraging, there is a challenge that cannot be
overlooked. Because fusarium has already damaged the infected seed,
reduced germination and yields can still be expected, even after heat
treatment.
The seed industry and farmers wanting to use their own bin-run seed
would need to balance that limitation against the benefits of being
able to eliminate fusarium pathogens, which would alleviate the risk of
introducing fusarium into uninfected fields. However, higher planting
densities likely would be needed to compensate for reduced germination
and yield.
Research has not yet been done on higher-density seeding.
The Winnipeg trials also found that heat treatments slightly reduced
plant height. Time to maturity increased by about one-third of a day.
Kernel weight was not affected.
The Cereal Research Centre did the heat treatments in a special
incubator. Gilbert said an ordinary oven won’t work, because it does
not create the air movement needed to prevent seed from baking.
Economics will influence how the findings are used. The treatments
might prove too costly for bulk volumes of grain needed by commercial
farmers for planting, but they could be a godsend for plant breeders
and seed companies needing uninfected seed for the development and
multiplication of new crop varieties.
Heat treatments might also help keep Alberta’s borders open to imports
of higher-value seed stocks from the eastern Prairies. They may also
ease Alberta’s concerns about feed imports from Manitoba and
Saskatchewan.
Jim Calpas, a pest risk manager with Alberta Agriculture, is keeping
the heat treatments in mind as he looks at how pelleting affects
fusarium-infected feed.
Calpas visited a pelleting plant where temperatures reached between 77
and 88 C while feed was preconditioned to make it warm and moist before
it was pressed into pellets. The ground-up feed was treated with steam
for up to two minutes.
Calpas said he wants to duplicate that process on a smaller more
controlled basis for study that will lead to specific recommendations.
Pelleted feed is now viewed as a potential carrier of fusarium into
Alberta, but that might change if heat applied during pelleting can
consistently kill the pathogens.
“We’re trying to reduce the amount of Fusarium graminearum that gets in
contact with our fields,” Calpas said.
“Intuitively, it makes sense that the heat treatment process has an
effect.”
Agriculture Canada’s research on heat treatments is funded by the
Alberta Agricultural Research Institute.
In addition to work at the Cereal Research Centre, the treatments are
also being studied at Agriculture Canada’s research centres in Lacombe,
Alta., and Swift Current, Sask.
At Lacombe, researcher Kelly Turkington said the 2001 trials on
uninfected barley and oats seed found no reduction in germination or
yield when temperatures reached 70 C. The results for this year’s
trials at Lacombe had not been reviewed as of Nov. 4.
At the Cereal Research Centre, emergence was reduced following heat
treatments of 70 C on uninfected seed. There was no reduction in
emergence when uninfected seed was treated at 30 or 50 C, Gilbert said.
The research builds on work started by the Canadian Grain Commission,
which had shown the treatments could eradicate fusarium pathogens from
seed without much effect on germination.
