Barley and wheat leaf rust warning for 2017

Barley leaf rust

  • Tenterden
  • South Stirling

Orange leaf rust pustules on barley leaves

Barley leaf rust pustules. Photo courtesy of: Geoff Thomas (DAFWA).

Crop protection development officer Alice Butler (DAFWA) has been finding leaf rust on barley regrowth from Tenterden to South Stirling.

Plant pathologist Kithsiri Jayasena (DAFWA) has found barley leaf rust (BLR) on regrowth barley when recently visiting South Stirling. The barley varieties were mostly Bass and Oxford and plants were at the ear emergence stage.

This indicates that the 2017 season is going to be another bad leaf rust year. Particularly, if farmers do not effectively manage regrowth barley that harbours the leaf rust pathogen. Famers that are using barley regrowth for animal feed need to be aware that the ungrazed regrowth can still harbour BLR.

Wheat leaf rust

  • Scaddan
  • Salmon Gums

rust pustules on a wheat leaf

Wheat leaf rust pustules. Photo courtesy of: DAFWA.

Crop protection development officer Jolie Delroy (DAFWA) has reported finding wheat leaf rust (WLR) on volunteer wheat (variety unknown) on a road verge at Scaddan. Jolie also found WLR on volunteer Mace wheat in a grower’s paddock at Salmon Gums. In both cases the plants were at the grain fill growth stage.

In late 2016, WLR was found in Grass Patch, Salmon Gums and Gibson and testing showed that the pathotype at Grass Patch is of the newest strain to be detected in WA, for which Mace has a MS-S reaction to.

Cereal leaf rust management strategies

Selecting a cereal variety with some leaf rust resistance is essential.

Currently barley varieties do not possess total resistance for the current leaf rust pathotype. So farmers will have to rely on varieties which carry adult plant resistant (APR) genes. Information on APR varieties is available in DAFWA’s Barley Variety Sowing Guide for Western Australia 2017.

Wheat varieties range in resistance from S to MR and rely on a combination of APR and/or single gene resistance. The latest wheat variety ratings can be found at DAFWA’s Wheat disease ratings.

Applying fungicides at seeding

There are two registered fungicide products for BLR. Both Systiva® (as seed dressing) and Uniform® (as in-furrow) use will delay early infection.

Seed dressings containing fluquinconazole or triticonazole and in-furrow fungicide triadimefon are registered for the suppression of WLR .

For more information visit DAFWA’s Seed dressing and furrow fungicides for cereals in Western Australia.

Effective foliar fungicide application post emergence

For BLR select a fungicide mixture which contains azole (epoxiconazole, cyproconazole) and strobilurin (pyraclostrobin and azoxystrobin). These product mixtures give good control of BLR if used at the right chemical rates.

Also barley varieties with APR resistance are susceptible to leaf rust at early growth stages so if infected they will respond to application of foliar fungicides during elongation and booting.

Last year DAFWA conducted a trial at Mingenew to investigate how Mace wheat responded to different foliar fungicide application timings for managing WLR. To see the results visit DAFWA’s Foliar Fungicide application timing for managing leaf rust in wheat, Mingenew 2016 trial report.

More barley and wheat foliar fungicide information can be found at DAFWA’s Registered foliar fungicides for cereals in Western Australia.

Growers urged to participate in Australian cereal rust survey

It is important that samples of all rusts are sent for pathotype testing. Infected leaf samples should be mailed in paper envelopes (do not use plastic wrapping or plastic lined packages) along with your details and collection information (location, variety etcetera) directly to the Australian Cereal Rust Survey, Plant Breeding Institute, Private Bag 4011, Narellan NSW 2567. Free reply paid envelopes can be ordered from the University of Sydney. For more survey information click here.

For more information about BLR and WLR and how to manage them visit DAFWA’s Diagnosing barley leaf rust and Diagnosing leaf rust of wheat pages.

For more information contact Kithsiri Jayasena, Plant Pathologist, Albany on +61 (0)8 9892 8477, Geoff Thomas, Plant Pathologist, South Perth on +61 (0)8 9368 3262 or Andrea Hills, Plant Pathologist, Esperance on +61 (0)8 9083 1144.