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Barley farmers face many
obstacles in the course of a growing sea-
son, but one threat is ever present:
leaf disease.
Kelly Turkington, PhD, and his col-
leagues at the Lacombe Research Centre,
know this all too well. The centre is one of
19 national agricultural research centres
operated by Agriculture and Agri-Food
Canada.
As a research scientist specializing in
plant pathology, Turkington has seen leaf
diseases ravage healthy crops.
“Leaf diseases are complex,” he said.
“They attack at different times and in
different ways, so we take a multi-faceted
approach to them.”
Unfortunately for the scientists, the
problems of leaf disease have only wors-
ened over time.
“We’ve seen a dramatic shift over
the last 25 years to a rotation based on
canola-cereal-canola. It’s a bad rotation
from a disease standpoint because it’s not
long enough to allow for decomposition of
pathogen-infested crop residues.”
Turkington said that two years is need-
ed between host crops.
“You must allow time for the residue
to dissipate. At one year, there’s sufficient
residue left in the field to cause disease.”
Breeding Success
“One line of defence involves co-operative
breeding programs,” said Turkington,
referencing Alberta Agriculture and Rural
Development in Lacombe, the University
of Saskatchewan and Agriculture and
Agri-Food Canada in Brandon, MB.
“We collaborate on the development
of breeding lines and varieties that are
resistant to disease.”
Farmers will appreciate that the added
input costs involved with this approach
are minimal.
“You’re just shifting to a variety with re-
sistance to disease,” Turkington said. “It’s
an easy technology and you don’t have to
worry about whether to spray.
Timing is Everything
In addition to broader disease strate-
gies, Turkington’s team is investigating
fungicide timing (flag leaf stage versus
flowering) and interactions with seed
treatments.
“It’s about timing,” said the researcher.
“Recently completed experiments assessed
the impact of fungicide timing on leaf
disease management in malting barley.”
There is interest in applying fungicide
at an early crop growth stage when herbi-
cides are applied.
“Farmers may assume that they’ve dealt
with the leaf disease problem when they
haven’t. Based on our findings around
how fungicides work and move in the
plant, and the key plant tissues that
contribute to grain filling in cereals, early
application is of little benefit. It’s best
to delay fungicide application to active-
ly protect the upper canopy of the leaf
tissue, which is important for grain filling
and yield.”
As for seed treatments, they’ve been
around for years, but there’s always room
for improvement.
“We’re looking at whether seed treat-
ments, apart from protecting the plant
when it’s emerging, can also protect into
the two-, three- or four-leaf stage,” said No-
ryne Rauhala, Turkington’s lead research
technician. “Can the treatments hold leaf
disease in check, especially if disease pres-
sure is high when they’re young?”
Strategies That Make Cents
“Yield loss from leaf disease ranges from
15 to 40 per cent,” said Turkington, “so
if you’re not mitigating your risk with
rotation, resistant varieties or fungicide, it
becomes costly.”
By Geoff Geddes
grain
science
news
managing leaf diseases
• If practical, use a rotation with
at least two years of a non-host
crop between barley crops.
• Use quality seed and a treat-
ment to ensure good stand
establishment.
• Grow a variety with resistance
to the diseases of concern.
• Regularly scout fields to identi-
fy leaf disease problems.
• When leaf disease risk is high,
apply a fungicide to protect
upper canopy leaves.
• As the crop starts to mature,
note what disease issues oc-
curred and use this information
to develop management strate-
gies for subsequent crops.
At the same time, he said that since re-
sistant varieties have minimal disease risk,
you may waste $7 to $15 dollars per acre on
fungicide and derive no benefit.
For optimal results, he said his team
balances lab and field work.
“Our disease resistance work is done
primarily in disease nurseries, but we also
collaborate across the Prairie region on
integrated disease management trials.”
Those trials reach from Beaverlodge to
Lethbridge in Alberta and east through
Saskatchewan (Scott, Indian Head and
Melfort), Manitoba (Brandon) and all the
way to Charlottetown on Prince Edward
Island.
There are a host of variables that the
barley farmer can’t control, from weath-
er to economics to changing consumer
demands. But leaf disease is one area
where—armed with the right tools and
strategies—the producer stands a fighting
chance.
HuntingCereal Killers
Lacombe’s research teambattles VIcious leaf diseases
Spring
2014
Grains
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