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Winter
2017
grainswest.com33
maP reaDing
FHB risk map have been used to help battle
F. graminearum
in
other regions where the fungus has long been an established
problem for farmers. They have been available in Manitoba and
parts of the United States for several years, and the maps were
added to Saskatchewan’s arsenal by the Saskatchewan Wheat
Development Commission (Sask Wheat) two years ago.
“Our board received a strong message from producers
that more resources were needed to help manage FHB,” said
Harvey Brooks, general manager of Sask Wheat.
Identifying areas of the province as high, medium or low
risk, the maps—posted on the Sask Wheat and provincial
government websites—indicate whether weather conditions
are favourable for the development of
F. graminearum
.
“Farmers located in zones with the requisite moisture and
high nighttime temperatures to warrant a ‘high risk’ or ‘medium
risk’ label should be checking their crops and weighing their
management options,” said Brooks. “Plants can’t get infected
until flowering, so if they’re at that stage and conditions are risky,
there is additional material online to guide producers through
critical spraying decisions: whether to spray, which fungicides
are approved for use with
F. graminearum
and the best times to
apply them.”
Although he also advocates use of the maps, Mitchell Japp,
provincial specialist for cereal crops with the Government of
Saskatchewan, agrees with Brooks that farmers should use
multiple resources to determine how they will limit
F. graminearum
infection. “The map is a good starting point to
indicate if there’s risk, but no tool is perfect,” he said.
Japp stressed that farmers still need to be in the field getting
a sense of what’s happening and factoring in local conditions.
“If you are at high risk when the crop head is emerging, which
is when the crop starts to become susceptible, it doesn’t
mean you should spray. Farmers must consider many factors,
including whether they or their neighbours have had FHB
before. They should look at what stage their crops are in, check
the weather, factor in the cost of applying fungicide, estimate
their crop yield and decide if applying fungicide will provide a
positive return on their investment.”
signs of things to come
If you’re worried that a child has chickenpox, you look for spots.
But how do you spot FHB in your crops?
“Symptoms in wheat initially appear as dead, prematurely
ripened portions of the cereal head affecting one or more
spikelets,” said Turkington. “With severe infections, the entire
head may prematurely ripen and there will be a brownish
discolouration of the stem directly below the head.”
Although the symptoms are similar for barley, Turkington said,
“head and kernel symptoms in barley are much less distinct and
can be easily confused with diseases such as spot blotch and
kernel smudge, or even hail damage.”
While knowing what to look for is crucial, knowing when to
look is also important.
“One of the best times to scout for head blight on cereal
crops is at the late milk to soft dough stages, because the
healthy tissues are still green and the infected tissues, which
appear bleached, are clearly seen,” said Michael Harding, a
plant pathology research scientist with Alberta Agriculture and
Forestry.
Bracing for imPact
Turkington warned that it is dangerous to treat Fusarium just
like any other run-of-the-mill cereal disease, given the negative
consequences it can have on producers’ bottom lines.
SPOTTING SYMPTOMS:
Fusarium head blight symptoms in
wheat include premature ripening and brownish discoloration of the
stem below the head, according to Agriculture and Agri-Food Canada
plant pathologist Kelly Turkington.