In areas that have received timely rains, it is time to scout for plant
disease.
“Barley growers should be on the lookout for net blotch, septoria and
scald,” said Jim Calpas, integrated pest management specialist with
Alberta Agriculture in Edmonton.
Net blotch is one of the most widespread barley leaf diseases. It is a
fungal disease named after the distinctive netted leaf symptoms that it
causes.
It also has a spot-blotch symptom that, as the name implies, is a dark
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brown oval spot on the leaf.
To complicate matters, there is another fungal disease called
spot-blotch that can be confused with the spot-blotch phase of net
blotch.
“Septoria is also a fungal disease that is a concern to barley
growers,” said Calpas. “Lesions usually occur first on the lower leaves
and appear as water soaked spots that develop greyish centres.
“Septoria can also infect the glumes later in the season. Scald is
another significant barley disease that is more common in the central
and northern parts of Alberta.”
Wheat growers also have to contend with septoria leaf and glume blotch.
Tan spot is another disease that is more of a problem in wheat.
Symptoms of tan spot begin as tiny brown flecks on the leaves that
develop into lens shaped blotches.
Many cereal leaf diseases can have multiple infection cycles following
periods of wet weather in the growing season. The incidence of and
associated losses to these diseases are typically more intense under
cereal-on-cereal rotations.
“Crop rotation serves as a preventative control strategy,” said Calpas.
“Seed treatment is always a good basic preventative measure for
seed-borne disease. Baytan 30 is a systemic seed treatment that
suppresses scald and net blotch on barley. Agrox N-M is another seed
treatment that includes net blotch control on the label.”
The fungicide Tilt is registered for control of these leaf diseases in
cereals with a single application at the beginning of stem elongation
to the emergence of the flag leaf generally suitable for control.
Tilt has three weeks of residual activity in the plant.
A second application before head emergence is often required for
control of septoria. There is a 45 day preharvest interval on Tilt.
Bravo 500 is registered for septoria leaf spot and glume blotch, as
well as tan spot control in wheat.
Use Dithane DG Rainshield NT for tan spot and septoria leaf blotch in
wheat.
Before using any chemical control, ensure the chemical is registered
for the disease of concern on the crop in question. Read and follow the
label directions.
