Grains Research and Development

Date: 04.03.2013

Plan to preserve rust resistance

Author: Professor Robert Park and Dr Will Cuddy
A photo of a leaf afflicted with rust

Variety selection is the first line of defence for growers keen to minimise the effects of cereal rust diseases in the 2013 growing season.

Growers are urged to eliminate varieties that are susceptible or very susceptible to rusts from their cropping programs to help preserve the disease resistance that protects many Australian crops. The risks of a large-scale rust outbreak and mutant rust isolates that can overcome resistance genes are of particular concern.

In 2011, an industry survey found that growers generally choose varieties based on yield potential, without considering the costs of disease management and yield losses. However, a variety’s resistance rating is an important consideration because a rust outbreak can reduce cropping returns by more than 50 per cent.

Rust facts

  • There are three rust diseases affecting wheat, stripe, stem and leaf, which all occur in Australia
  • Rusts are caused by fungi, and the wind can quickly spread rust spores over large areas
  • Rusts can mutate (alter or change) to overcome resistance genes, so it is important to check the resistance rating of cultivars using a current disease guide
  • Rust tends to become a problem in areas where susceptible varieties are grown. This is because inoculum levels build up on volunteer plants during summer and autumn, allowing rusts to re-establish early in the following cropping cycle
  • Rust epidemics are more common following wet summer and growing-season conditions

The Australian Cereal Rust Control Program Consultative Committee is also keen to see growers reduce their reliance on chemical inputs for managing rust incursions. In the past, many growers have relied on fungicide applications to control rust diseases. While this is effective for managing leaf and stripe rusts, stem rust is less responsive to fungicide treatment, particularly in dense crop canopies, because applications may not reach all stems.

The following five-part strategy is recommended to help growers manage rust diseases.

  1. Remove the green bridge by mid-March or four weeks prior to sowing.
  2. Plant varieties with adequate resistance to stem, stripe and leaf rusts.
  3. Apply fungicide to seed or fertilisers where needed for early season rust suppression.
  4. Monitor crops for rust and, if needed, apply foliar fungicide for disease control.
  5. Work with your neighbours, local community and the wider grains industry to monitor, report and manage rust diseases.

A planned approach to rust management at the beginning of the growing season, instead of when an outbreak occurs, aims to reduce the potential for major yield losses resulting from rust.

Growers uncertain about the susceptibility of varieties are encouraged to consult their local agronomist, plant pathologist, regional cereal disease guide or visit the Rust Bust website (www.rustbust.com.au).

Rust Bust Logo

The Rust Bust is an initiative of the Australian Cereal Rust Control Program Consultative Committee, supported by the GRDC.

Established in 1973, the Australian Cereal Rust Control Program is mostly funded by grain growers through the GRDC. It has a national mandate and nodes at the University of Sydney, CSIRO Plant Industry, the University of Adelaide, the New South Wales Department of Primary Industries and the International Wheat and Maize Improvement Center.

More information:

Professor Robert Park,
02 9351 8806,
robert.park@sydney.edu.au
;

Dr Will Cuddy,
02 9351 8821,
will.cuddy@sydney.edu.au
;

www.rustbust.com.au

www.grdc.com.au/GCTV

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