Symptoms are very similar to stripe rust in wheat. Bright yellow-orange spores form pustules which occur in stripes along the leaves, (Figure 2.25). In young leaves, the pustules tend to be scattered across the leaf. Spores rub off easily onto a finger. Barley grass stripe rust and barley stripe rust have the same symptoms. If barley stripe rust is suspected check a Victorian Cereal Disease Guide (AG 1160) for a resistance rating. Unusually severe reactions (ie. where a variety has a good resistance rating to barley grass stripe, but there are severe rust symptoms) could indicate the exotic barley stripe rust and must be reported via the Exotic Plant Pest Hotline (1800 084 881).
Figure 2.25 Barley grass stripe rust symptoms on barley
Barley grass stripe rust survives over summer on self-sown barley and barley grass. Little is known about the conditions that favour its infection.
The most effective way to control the three rusts of barley is to grow varieties with resistance. By growing resistant varieties:
- the amount of disease in a crop and neighbouring crops are reduced,
- the chance of the rusts mutating, enabling them to attack previously resistant varieties is reduced
- and the resistance varieties currently available are better protected.
It is important to note that new races of barley rust can develop that overcome varieties with resistance. To select varieties with effective resistance, it is essential to consult an updated Victorian Cereal Disease Guide (AG 1160)
It is important to remove the inoculum provided by self sown barley over summer where possible. These rusts survive predominantly on summer volunteers which provide significant inoculum loads if left unmanaged. Even small amounts of rust, present during autumn, can multiply to cause serious yield losses if spring weather conditions are favourable for rust development. Use grazing or herbicides to remove green growth, especially during wet summers.
There are no seed treatments registered for rust control in barley in Australia. However, seed treatments are necessary to control bunts and smuts, as well as other barley diseases. Some of the seed treatment or in-furrow fungicides may also prevent early leaf rust infection. Efficacy varies between active ingredients, so it is strongly recommend that a SARDI Cereal Seed Treatments Guide be consulted.
There is a range of foliar applied fungicides available that will give disease suppression of leaf rust in barley. Research by DEDJTR and Birchip Cropping Group has shown that the most effective suppression of leaf rust was achieved when foliar fungicides were applied early in an epidemic. Additional applications may also be required where rust pressure is sustained during a wet spring. Fertiliser applied fungicides can also provide suppression of barley leaf rust. However, the effectiveness of such treatment is restricted to the seedling stages of crop development and additional application/s of foliar fungicide are required if the epidemic persists during the spring months.
More detailed information can be obtained from:
DEDJTR AgNotes Series www.vic.gov.au/graindiseases
Victorian Cereal Diseases Guide (AG 1160) www.vic.gov.au/cerealdiseaseguide
Victorian Winter Crop Summary www.vic.gov.au/victorianwintercropsummary
Cereal Seed Treatment Guide (SARDI) www.pir.sa.gov.au
Wallwork H (2015) Cereal Seed Treatments (SARDI) www.pir.sa.gov.au, http://www.pir. sa.gov.au/ data/assets/pdf_file/0005/237920/ cerealseedtreat2015_web.pdf
For rust identification, send rusted plant samples in a paper envelope (do not use plastic wrapping) to: Australian Cereal Rust Survey.
Plant Breeding Institute. Private Bag 4011, Narellan NSW 2567
SCALD OF BARLEY