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“When it gets going, it can really
cause a lot of damage,” Fetch said.
“The potential yield loss can be total, in
epidemic conditions.”
Sridhar Bhavani has seen the
devastating effect of Ug99 from ground
level. Based in Nairobi, Kenya, he is a
wheat pathologist and breeder who is
co-ordinating screening efforts for the
Consultative Group on International
Agricultural Research.
Bhavani said comprehensive tests
of the Ug99 strain in 2008 and 2009
showed that more than 90 per cent of
the world’s wheat varieties are vulnerable
to the stem rust, including those used in
Canada.
“It is a devastating disease to wheat
production, as susceptible varieties can
result in 100 per cent losses,” he said. “It
is considered a threat to global wheat
production.”
As it marched across an unprepared
Africa in epidemic levels, Bhavani said,
the losses were simply devastating.
Some of the more sophisticated farms
in East Africa had the resources to fight
back against the disease, but still suffered
major losses.
“Large-scale farmers were able to
avert losses by spraying fungicides,” he
said. “However, they still lost 10 to 40
per cent of the crop due to high disease
pressure.”
Bhavani said a much larger impact was
felt by small, traditional farmers, many of
whom were growing heritage varieties
and lacked the resources to spray.
“Small-scale farmers lost their entire
crop if it was unsprayed and they were
growing susceptible varieties,” he said.
After more than a decade of fighting
the disease, things are now starting to
look up, Bhavani said. Today, after years
of research and breeding, there are 45
varieties of Ug99-resistant wheat in the
world. Two of these cultivars—Robin and
Eagle 10—now occupy about 40 per
cent of the wheat area in Kenya.
Preparations for the arrival of Ug99 in
Canada are now well underway, Fetch
said. After five years and $13 million
worth of research, AAFC scientists
have discovered three genes that
provide resistance to Ug99 infection.
In November, the federal government
pledged an additional $1.26 million to
continue with phase two of this genetic
research.
The ultimate goal is to create a strain
of wheat that is resistant not just to
the Ug99 wheat rust, Fetch said, but
to possible future
mutations. This will
be done by including
multiple resistant
genes into one plant.
“We want to stack
the genes, so you
have more than one
gene in the cultivars
we’re developing,”
he said.
The need for multiple resistant genes is
illustrated by the experience of Ethiopia,
Fetch said, where farmers relied heavily on
wheat with a single rust-resistant gene.
“They relied on one single gene called
Sr31, and it was effective for several
decades,” he said. “But then, when
Ug99 came along, it attacked it, and
when that gene went down there was a
lot of susceptible wheat.
“They had all their eggs in one basket
… and we don’t want to do that.”
In the meantime, Fetch said farmers
should always watch their fields closely
and report any strange symptoms. In the
case of Ug99, symptoms include raised,
brownish-red, blister-
like lesions that are
elliptical in shape.
The worst-case
scenario for farmers is
that a large infection
breaks out in the
southern United
States in January,
Fetch said. This
would generate a
large mass of spores, which could then
be carried up to Canada by prevailing
winds as planting is underway in the
spring. Such conditions could lead to
widespread infections, and leave Ug99
the whole summer to wreak havoc in
Canadian fields.
Spring
2014
grainswest.com
43
“If it gets to South
America, then it’s
likely a matter of three
to five years before it
gets to Canada.”
–Tom Fetch
The coloured portion of the map illustrates where wheat is grown in
the Prairies. The red portion indicates areas that receive enough rain
and humidity to favour stemand leaf rust infection.