Grains Research and Development

RustLinks

The Australian Cereal Rust Control Program Consultative Committee (ACRCP CC), with support from the GRDC are proud supporters of the ‘Rust Bust’ campaign. In 2013 the Rust Bust messages are clear and simple:

  • Eliminate S and VS varieties from your rotation
  • Remove the green bridge (volunteer plants) at least four weeks prior to the intended sowing date within a district.
  • Grow varieties with adequate resistance to stem, stripe and leaf rusts.
  • If needed, apply fungicides to seed or fertilisers for early season rust suppression.
  • Monitor crops for rust and if needed, applying foliar fungicides for disease control.
  • Communicate with your neighbours to manage disease outbreaks.

These strategies will benefit you, your industry and your neighbour.

The Rustlinks site brings information on rust research, development and extension. Click on the following links below to find out more information:



Overview

Rust diseases are caused by fungi that are members of the order Uredinales and class basidiomycetes. The name “rust” is due to diseased plants showing rust-coloured orange patches on infected parts.

In addition to structural features that are typical of basidiomycetes, they have complex life cycles with up to five forms of spore being formed. In Australia one of these forms, the urediniospore, is rust coloured.

The spores are easily spread by the wind and are brought out of the air by rain. They can survive harsh winters but need relatively warm weather to germinate.

There are three rust diseases of wheat and triticale prevalent in Australia: stripe, stem and leaf; in addition leaf rust of barley and stem and crown rust of oats are also significant. All of these are highly infective diseases that can spread widely throughout a region.

All cereal rusts require a live host plant for survival. Without a source of live plants to form a green bridge between seasons, the supply of inoculum to start the next epidemic is cut.



Stripe rust Colin Wellings ACRCPStripe rust

Stripe rust is caused by the fungus Puccinia striiformis. It is a serious problem on wheat in regions where cooler temperatures prevail through the wheat growing season. Barley and some other grasses and cereals are also affected.

Symptoms of stripe rust are long stripes of small yellowish orange pustules on the leaves. These pustules consist of masses of urediniospores. It can sometimes be confused with leaf rust or stem rust.

The disease is first seen as small yellow pustules resembling stitching on the leaves running parallel to the long axis of the leaf that coalesce to form stripes. These break open some days later to reveal a mass of rust-coloured spores. The stripes can turn black as the disease progresses and a new type of spore, the teliospore, develops. Under high disease pressure, the flowering spike may become heavily infected. The infection stresses the plant causing it to dry out as it matures and restrict grain filling

(Image: Stripe rust Colin Wellings ACRCP)



Stem Rust Robert Park ACRCPStem rust 

Stem rust of wheat, triticale and barley is caused by the fungus Puccinia graminis f. sp. tritici. Stem rust on rye is caused by Puccinia gramins f. sp. secalis. Stem rust on barley may be caused by wheat stem rust, rye stem rust or a hybrid of the two – hence a rust sample is important to identify the pathogen present.

The disease is first seen as elongated elliptical blisters on the leaves and stems of the plant running parallel to the long axis of the leaf or stem. These break open some days later to reveal a mass of rust-coloured spores. In contrast to the other rusts, stem rust will infect the true stem and so drastically restrict grain filling and severely limit yield. Later in the season, a new spore type, the teliospore, forms and the lesions turn black.

(Image: Stem Rust Robert Park ACRCP)



Leaf rust Robert Park ACRCP

Leaf rust 

The most notable signs of leaf rust infection, caused by the pathogen Puccinia triticina (formerly recondita f. sp. tritici), are the reddish-orange spore masses of the fungus breaking through the leaf surface. The leaf rust spores are carried by wind currents. On older leaves the rust spores are usually only found on the upper leaf surface.

  (Image: Leaf rust Robert Park ACRCP)









Barley leaf rustBarley leaf rust

Barley leaf rust is caused by the fungus Puccinia hordei

Pustules of leaf rust are small and circular, producing a mass of orange-brown powdery spores predominantly on the upper leaf surfaces. Later in the season, pustules also develop on leaf sheaths. . In South Australia the weed Star of Bethlehem is an alternate host for the disease.

(Image: Hugh Wallwork, SARDI)