By Kate Glastonbury, Grains Biosecurity Officer, New South Wales
Barley stripe rust (Puccinia striiformis f. sp hordei) poses a significant threat to wheat and barley production globally. Although not present in Australia, the grains industry is going to great lengths to keep this damaging disease from being introduced.
Barley stripe rust is a fungal disease that has impacted crop yield and grain quality across Europe, the UK, South America, Asia, Mexico, and the USA.
Damage to barley plants varies depending on the plant growth stage.
Crop losses due to the disease are typically around 10 per cent, but in susceptible varieties they may be up to 100 per cent.
The disease is known to reduce plant and root growth, increase water loss and cut photosynthate availability, resulting in fewer and lighter kernels.
The estimated potential cost to the Australian barley industry due to uncontrolled epidemics of leaf and stem rust is over $100 million. This figure provides a benchmark for the potential impact of barley stripe rust in Australia and highlights the critical importance of robust biosecurity measures.
Early identification of symptoms, understanding the potential impacts on your crops, and implementing effective measures to help reduce the likelihood of it entering and impacting your property is key.
Recognising the symptoms
Barley stripe rust primarily attacks the leaves, but a heavy infestation can also affect leaf sheaths and grain heads.
The most notable symptom of stripe rust is the presence of yellow-orange pustules arranged in stripes on the upper leaf surface. The disease is sometimes referred to as yellow rust.
In seedlings or highly susceptible varieties, the rust may cover the entire leaf and extend into the leaf sheaths and grain heads. The disease can build up rapidly if conditions are cool and wet, and infection is often first noticed as hot spots or patches of lighter coloured crops within the crop.
Stripe rust symptoms often appear earlier than other rusts due to lower temperature requirements for development. In Australia, conditions for development would be most suitable between April and December, with potential infestations becoming obvious in crops by September.
The optimum conditions for barley stripe rust spores are 3-8 hours in high humidity, and temperatures ranging between 13-18 °C. However, spores can germinate in temperatures between 5-20 °C.
Disease similarities
Barley stripe rust can display similar symptoms to barley grass stripe rust and wheat stripe rust, that are already established in Australia. It may also appear similar to other types of rust, such as wheat stem rust and barley leaf rust as shown in the images below, though these typically have spores that are browner in colour.
Protecting your farm and region
Barley stripe rust spores are small, light, and can spread over large distances via wind, surviving for several days. These spores can also attach to clothing, tools and machinery, facilitating their spread between farms, across regions and even internationally. It’s important to note that this disease is not seed borne.
Once introduced to a new region, there is high potential for spread, as evidenced by the movement of this disease from Colombia to Chile in a few years from wind dispersal.
Measures to reduce your risk:
If you spot anything unusual in your crop, call the Exotic Plant Pest Hotline on 1800 084 881. Make sure to document any relevant details including GPS location, parts of plant affected, variety and take good quality images showing close ups of symptoms, as well as a photo of the entire plant.
For more information, refer to the Grains Farm Biosecurity Program’s (GFBP) fact sheet on barley strip rust.
Visit the Grains Farm Biosecurity website for more practical resources that include fact sheets, videos, how to guides, online training and strategies to assist in the management of grains farm biosecurity risks.
