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Published Date: 2019-05-02 09:47:08
Subject: PRO/PL> Leaf rust, barley - UK: (Scotland)
Archive Number: 20190502.6452058
LEAF RUST, BARLEY - UK: (SCOTLAND)
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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: Sun 28 Apr 2019
Source: The Scottish Farmer [edited]
https://www.thescottishfarmer.co.uk/arable/17603054.spring-crop-spraying-brown-rust-cause-concern-in-scotland/


It's a bit of a rarity in Scotland, but this [2019] season unusually high brown rust pressures have been affecting winter barley. That should raise alarm bells and growers should factor this into fungicide plans, according to Syngenta's Iain Lindsay.

Brown rust can be found in several varieties, he said, with weather conditions and crop growth having fuelled the disease. "Winter barley crops are much further forward, and the thick canopies have created a microclimate that favours brown rust."

"The weather wasn't wet enough for high levels of the usual rhynchosporium and net blotch. Now that brown rust is in crops, it will be important to be on guard. Consider a fungicide not only against rhynchosporium and net blotch, as these may still come, but also for good brown rust control."

As well as in winter barley, there is also a risk to spring barley, depending on the weather. "Warmer conditions will help brown rust pressure during the summer."

[Byline: Ken Fletcher]

--
Communicated by:
ProMED-mail
<promed@promedmail.org>

[Barley leaf rust (or brown rust) is caused by the fungus _Puccinia hordei_ (previously _P. striiformis_ f.sp. _hordei_) which affects only barley. 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 crop plants 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. Monitoring and resistance breeding programmes have been established in many affected areas to counteract pathogen adaptation by continuously developing new barley varieties.

The other barley diseases mentioned above are scald (or leaf blotch) caused by _Rhynchosporium secalis_ and net blotch caused by _Pyrenophora teres_. For more information on these diseases see previous ProMED-mail posts in the archives.

Maps
UK:
http://www.lib.utexas.edu/maps/europe/united_kingdom.gif (with regions) and
http://healthmap.org/promed/p/280

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,
https://grdc.com.au/~/media/images/ground-cover/ground-cover-105/p29130501rprustcolumn03julyjpg.jpg,
http://media.padil.gov.au/Species/136639/7736-large.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
Additional news story:
https://www.syngenta.co.uk/news/product-update/heightened-brown-rust-levels-affecting-scottish-barley
Information on barley leaf rust:
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,
https://www.agric.wa.gov.au/mycrop/diagnosing-barley-leaf-rust,
https://www.syngenta.com.au/news/broadacre/growers-embrace-new-leaf-rust-treatment,
http://ipm.ucanr.edu/PMG/r730100611.html, and
https://www.annualreviews.org/doi/full/10.1146/annurev-phyto-080614-120324
_P. hordei_ taxonomy and synonyms:
http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=444035 and
http://www.speciesfungorum.org/GSD/GSDspecies.asp?RecordID=444035
Syngenta UK:
https://www.syngenta.co.uk/
- Mod.DHA]

See Also

2015
----
Leaf rust, barley - Australia: (WA) 20150811.3571139
2010
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Leaf rust, barley - Argentina: (BA) new strain 20101028.3909
Fungal diseases, cereals - Germany: (SN) 20100428.1370
2009
---
Cereal rusts - Australia: (WA) alert 20090820.2948
1999
---
Crop diseases - Canada (Manitoba) (02) 19990825.1484
.................................................sb/dha/mj/dk

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