Barley leaf showing typical small brown rectangular lesions with yellow margins
Pathogen now established in Tasmania
Ramularia leaf spot of barley, a disease caused by the fungus Ramularia collo-cygni, was first detected in December 2016 at a barley trial site near Hagley in northern Tasmania. This was also the first detection of this pathogen in Australia. Despite early eradication attempts, Ramularia has since been detected at numerous sites in Tasmania, and in most Australian grain growing regions. National and state authorities have deemed it not technically feasible to eradicate meaning that it is now formally established and should be managed like other pests and diseases of cereals.
Symptoms
Ramularia hampers leaf development which can lead to loss of green leaf area in crops, and can result in yield loss.
Symptoms include small brown rectangular lesions with yellow margins within the leaf veins, visible from both sides of the leaf but most obvious on the exposed upper leaves after flowering.
Growers should be on the lookout for barley plants showing these symptoms—but note these can be easily confused with net blotch that is common on other grasses in Australia. A laboratory test is required for proper diagnosis.
Ramularia is primarily a pathogen of barley, but has also been known to cause disease on other cereals and grasses such as English couch grass, Kentucky blue grass, perennial ryegrass and prairie grass. It has also been detected on barley straw.
Management issues
Whilst it spreads via spores to nearby hosts, evidence suggests that long distance spread is limited to infected sown seed.
The disease is suited to Tasmania’s cooler climate and it is most common in northern Britain and other temperate regions including northern Europe, South America and New Zealand.
It is likely that the disease can be well managed with appropriate fungicides and, where possible, the use of Ramularia-free seed. Harvest machinery should be cleaned of seed between sites, and volunteers controlled where the disease has been confirmed.
What to do if you think you have found Ramularia leaf spot of barley
Barley leaf showing white mycelium on the surfaces of lesions
Plant Diagnostic Services in Biosecurity Tasmania (NRE Tas) will test barley samples suspected of being infected with Ramularia leaf spot.
Specimens or images can be submitted to a NRE Tas plant pathologist - call 1300 368 550 to be directed to a plant pathologist.
Samples of symptomatic barley leaves should be placed in sealed double plastic bags and sent to:
NRE Tas Plant Diagnostic Services
13 St Johns Avenue
New Town, TAS 7008