Start scouting for leaf diseases

Reading Time: 2 minutes

Published: July 18, 2002

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

Read Also

 clubroot

Going beyond “Resistant” on crop seed labels

Variety resistance is getting more specific on crop disease pathogens, but that information must be conveyed in a way that actually helps producers make rotation decisions.

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.

About the author

Alberta Agriculture

News release

explore

Stories from our other publications