Investment in science and industry development key to profitable agrifood sector 2

Funding and collaborators

GRDC; Landmark, Imtrade, Liebe Group and Northampton Agriservices

Image 1 Powerdery mildew in wheat

Image 2 Ciara Beard in a wheat crop infected with powdery mildew

Article 39: Managing leaf rust in barley

Putting up resistance to rust

Science team: Geoff Thomas (project leader), Dr Kithsiri Jayasena, Andrea Hills, Laurie Wahlsten, Jason Bradley

Leaf rust caused by Puccinia hordei is a significant disease of barley in WA. It is an aggressive and difficult foliar disease to control and can be a recurring problem in crops in the southern high rainfall zones.

Infection leads to the production of pustules that give the appearance of ‘rust’ on the leaves. The pustules are small and circular, producing a mass of orange-brown spores predominantly on the upper leaf surfaces. As the crop matures, the pustules turn dark and produce black spores embedded in the old plant tissues and stems.

Barley leaf rust can reduce grain yield by over 30% in severe infections. A GRDC-funded research project focuses on steps to prevent its spread.

The project encourages barley growers to use all the tools available for rust management including:

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  removing the green bridge (volunteer cereals)
  
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  growing varieties with adequate resistance to leaf rust
  
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  applying fungicides to seed for early season rust suppression
  
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  monitoring crops for rust and if needed, applying foliar fungicides for disease control.
  

Continued monitoring of all rust pathotypes will help identify and respond to changes in the virulence of rust. Aerial spore trapping of rust is being investigated for regional early warning and work continues on identifying the optimum times to apply fungicide to fight barley leaf rust.

HIGHLIGHTS

• 
  This project aims to manage leaf rust of barley, a recurring problem in southern high rainfall zones of Western Australia. Leaf rust can reduce grain yield by over 30% in severe infestations.
  
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  Spore traps are used extensively to monitor airborne cereal foliar pathogens such as rusts to warn the growers in the region.
  
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  Yield loss in barley varieties with combinations of resistance genes are tested against fungicides.
  
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  The timing of applications of in-crop foliar fungicide in relation to rust is being addressed.
  

Funding and collaborators

GRDC, Tel Aviv University (Institute for Cereal Crops Improvement ICCI), University of Sydney.

Image 1 Rust on a barley leaf

Image 2 DAFWA Research Officer Dr Kithsiri Jayasena with a spore trap to monitor airborne pathogens

Canola crops: keeping sclerotinia and blackleg at bay

Science team: Dr Ravjit Khangura (project leader), M. Aberra, Stuart Vincent, Andrea Hills, Ciara Beard, Anne Smith

Sclerotinia stem rot is a fungal disease that attacks canola as well as over 400 broadleaf species worldwide. The complexity of the stem rot pathogen and lack of genetic resistance pose significant agronomic challenges to growers and advisers, especially in tight rotations and in medium to high rainfall areas. Losses to sclerotinia in WA alone were estimated at $59 and $23 million in 2013 and 2014, respectively.

To provide growers with the best disease management package, DAFWA’s research over the past six years has focused on factors affecting disease development, product effectiveness, and the timing of fungicide applications.

Field trials have shown that effective control can be achieved by applying registered fungicide matched with the timing of sclerotinia spore release.

In 2015 the most effective and economical treatment was to apply fungicide at 25% or 50% bloom, ensuring maximum petals were covered. A well-timed single spray resulted in an increase in seed yield of 29% (compared with untreated plots), resulting in a $178/ha net return. Whereas, fungicide applied at late bloom stages were not economical (Fig. 1).

Blackleg caused by Leptosphaeria maculans is also an on-going issue. A major focus of research is to improve blackleg management strategies under tight canola rotations and determine the risk of breakdown of resistance.

Research indicates that blackleg is most economically controlled with seed dressing in conjunction with in-furrow fungicide application. Foliar applied fungicides have a role in in-crop disease management, particularly if targeted at early stages of crop development.

Data collected in the fungicide trials has been used to develop and validate the fungicide spray decision tool that can be accessed online at agric.wa.gov.au.

Ongoing research will focus on judging the optimum time for applying fungicide and developing integrated approaches to managing sclerotinia and blackleg profitably.

Researchers will use current and future epidemiological data to develop a decision support system that will provide early alerts of risk periods and help growers to make decisions about the use of fungicide sprays.