A ProMED-mail post <http://www.promedmail.org>
ProMED-mail is a program of the International Society for Infectious Diseases <http://www.isid.org>
Date: Thu 6 Aug 2015
Source: The Esperance Express [edited]
<http://www.esperanceexpress.com.au/story/3261716/farmers-hit-with-barley-leaf-rust/?cs=1520>
Esperance region hit with barley leaf rust
The Esperance region is experiencing its 1st widespread barley leaf rust infestation in close to a decade. Growers were now being warned to monitor their barley crops closely for evidence of the rust.
Farmanco's [agricultural service] Phillip Smyth discovered a barley rust infection in late June [2015]. "Since then I've seen it pretty consistently in the region. It's widespread in low levels, with trace levels in nearly all varieties," he said. The exact location where the spores were coming from was unknown, however they were believed to be a result of last year's [2014] untreated crop re-germinating.
"We haven't had a year where we've found it this widespread since 2006," Smyth said. "It's up to 45 per cent in yield loss with barley leaf rust, it can be quite aggressive," he said. Local farmers could see losses of around [AUD] 300 [about USD 219] per hectare if the disease is left uncontrolled.
Managing the disease can be difficult once it has settled in. Farmers are encouraged to use foliar fungicides with fertiliser (in-furrow) or seed dressing fungicides to prevent barley rust infection and spread.
[byline: Sarah Corridon]
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communicated by: ProMED-mail <promed@promedmail.org>
[Barley leaf rust (or brown rust) is caused by the fungus _Puccinia hordei_. Related pathogens affect wheat and rye.
The disease reduces the photosynthetic potential of the plant and can cause serious yield and quality losses. Symptoms include brick-red pustules on leaves, stems, and later on heads. Infection of the host can occur within hours and epidemic severity increases exponentially over time.
Spores are produced as the crop ripens and are spread by wind and mechanical means. The fungus needs living tissue to survive between seasons. Volunteer cereal plants (as suspected above) and certain wild grasses may generate a "green bridge" providing inoculum to infect new crops. Disease management relies mainly on timely fungicide applications, choice of crop cultivars and control of reservoir hosts.
Crop monitoring is important for early discovery of infection so action can be taken to limit pathogen spread as well as build-up of inoculum.
New even more virulent strains of cereal rusts are emerging worldwide.
In Western Australia (WA), a new pathotype of _P. hordei_ was detected in 2013 reducing leaf rust resistance in several varieties known to carry the Rph3 resistance gene. Monitoring and resistance breeding programmes have been established in WA and many other affected areas to counteract pathogen adaptation by continuously developing new barley varieties.
Maps
Australia (with states):
<http://www.webookaustralia.com/images/australiamap.jpg> and <http://healthmap.org/promed/p/47403>
Western Australia:
<http://www.ozhorizons.com.au/western_australian_map>
Pictures
Barley leaf rust:
<http://www.scienceinpublic.com.au/wp-content/uploads/Dr-Lee-Hickey-rust-on-barley.jpg>,
<http://www.bayercropscience.co.uk/media/86150/brown-rust_375x225.jpg>,
and
<https://www.agric.wa.gov.au/sites/gateway/files/styles/page_featured_image/public/Barley%20leaf%20rust%202%20cropped.jpg?itok=mFRc9Hdk&c=4129059b4526672de83a6c77a3cb330a>
Links
Information on barley leaf rust:
<http://oak.ppws.vt.edu/stromberg/b_leaf_rust.html>,
<http://www.agroatlas.ru/en/content/diseases/Hordei/Hordei_Puccinia_hordei/>,
<https://www.agric.wa.gov.au/barley/managing-barley-leaf-diseases-western-australia?page=0%2C2#smartpaging_toc_p2_s0_h2>,
<http://www.bayercropscience.co.uk/your-crop/crop-diseases,-weeds-and-pests/diseases/barley-diseases/brown-rust/>,
and
<http://www.ipm.ucdavis.edu/PMG/r730100611.html>
New _P. hordei_ pathotype in WA:
<http://www.grdc.com.au/Media-Centre/Hot-Topics/Barley-leaf-rust-in-Western-Australia>
_P. hordei_ taxonomy and synonyms:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=444035>
and
<http://www.speciesfungorum.org/GSD/GSDspecies.asp?RecordID=444035>
Farmanco crop consultants:
<http://www.farmanco.com.au/>
- Mod.DHA]
[See Also:
2010
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Leaf rust, barley - Argentina: (BA) new strain 20101028.3909 Fungal diseases, cereals - Germany: (SN) 20100428.1370
2009
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Cereal rusts - Australia: (WA) alert 20090820.2948
1999
---
Crop diseases - Canada (Manitoba) (02) 19990825.1484]
Topics
Species
