Bayer Crop Science Australia logo Crop Science Australia logo
Search
Search
Search

Leaf rust

Puccinia triticina – (Wheat leaf rust), Puccinia hordei – (Barley leaf rust), Puccinia coronata f.sp. avenae – (Oat leaf rust)

Leaf rust, also known as crown rust in oats, is a common disease infecting wheat, barley and oat crops throughout Australia. A specific fungal pathogen causes the disease in each crop, so spread from one crop to the other isn’t possible. In susceptible wheat and barley varieties, yield losses of up to 30 and 45 per cent respectively can occur, whilst reductions in forage and grain yields are common in oats.
Leaf rust

 
 
 

Description

Easily diagnosable, leaf rust is mostly found on the upper leaf and is characterised by small, round, oval or oblong-shaped, raised light brown to orange spore masses, known as pustules. As crops mature the pustules darken and small black teliospores form in the leaf. Yellowing of the leaf around pustules is common and leaves often wither and die back from the tip. In severe infections grain can become shrivelled, affecting yields and reducing quality.

Leaf rust requires green host plants, often referred to as a ‘green bridge’, to survive from one season to the next. Hosts include volunteer cereals and some weed species. Wet summers favour the growth of a green bridge and therefore the risk of early rust infections is increased, particularly when followed by wet, warm (10 – 22 °C) and humid spring conditions. Initially, leaf rust appears as a ‘hot spot’ of infection, from which wind-borne spores rapidly spread the disease throughout the crop. 

Control

There are a number of strategies available particularly to prevent leaf rust, which should be the focus rather than relying on curative measures. To prevent or reduce yield losses from leaf rust it is essential to plant resistant varieties. Growers should utilise the most up-to-date leaf rust ratings for the varieties of cereals grown in their regions.
 
The green bridge should be controlled or removed, either by grazing or spraying volunteer cereals and weeds out at least four weeks prior to sowing. This will help reduce the risk of an early infection.
 
Some fungicide seed dressings, including Jockey® Stayer® can be used in wheat. Jockey Stayer will control leaf rust for up to four weeks after planting (at the 4.5 L/tonne rate) then provide suppression thereafter. Even coverage of seed is essential.
 
Crops should be monitored for symptoms and where no seed treatment has been used, a protectant fungicide spray applied at first node is recommended, particularly in high risk crops.  Many current fungicides are effective as protectants only. In contrast, Prosaro® and Aviato® XPro® have both protectant and curative properties which both protect the crop from new infections and control recent infections.
 
Prosaro is registered for the control of leaf rust in barley (Puccinia hordei), oats (Puccinia coronata f.sp. avenae) and wheat (Puccinia recondita f.sp. tritici, Puccinia triticina). Aviator XPro is registered for the control of leaf rust in barley (Puccinia hordei).

Related Products

Aviator Xpro Fungicide
Prosaro


References

Department of Primary Industries and Regional Development (DPIRD) (2016), ‘Diagnosing leaf rust of barley’,https://www.agric.wa.gov.au/mycrop/diagnosing-barley-leaf-rust

Department of Primary Industries and Regional Development (DPIRD) (2016), ‘Diagnosing leaf rust of wheat’,  https://www.agric.wa.gov.au/mycrop/diagnosing-leaf-rust-wheat

Department of Primary Industries and Regional Development (DPIRD) (2017), ‘Oats: Leaf Diseases’, https://www.agric.wa.gov.au/oats/oats-leaf-diseases?page=0%2C2

Henry, F (2014), ‘Leaf Rust of Wheat’, Agriculture Victoria, http://agriculture.vic.gov.au/agriculture/pests-diseases-and-weeds/plant-diseases/grains-pulses-and-cereals/leaf-rust-of-wheat

GRDC (2016), ‘Tips and Tactics. Leaf rust in wheat. Northern, Southern and Western Regions’, GRDC Grow Notes, https://grdc.com.au/__data/assets/pdf_file/0021/142545/grdc_tips_and_tactics_leaf_rust_web.pdf.pdf

McClean, M and Holloway, G (2012), ‘Rusts of Barley’, Agriculture Victoria, http://agriculture.vic.gov.au/agriculture/pests-diseases-and-weeds/plant-diseases/grains-pulses-and-cereals/rusts-of-barley