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: 20 January 2009
Source: Farmers Guardian [edited]
<http://www.farmersguardian.com/story.asp?sectioncode=19&storycode=23861>

High disease levels in winter barley

Winter barley growers are being advised to watch out for high disease levels appearing in crops. According to Syngenta Seeds cereal product development manager Simon Phillips, high levels of net blotch are present in early-drilled winter barley crops around the country, with some also succumbing to patches of mildew. "The problem has probably been exacerbated by wet weather in November and December [2008],"
says Mr Phillips.

Syngenta Crop Protection technical manager, Iain Hamilton says that growers should be prepared to spray with an early fungicide if necessary. "Keeping disease out before it escalates is especially important in barley because lower leaves can contribute even more to yield than they do in wheat, and because diseases such as net blotch and rhynchosporium can be difficult to eradicate once established."

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

[Net blotch of barley is caused by the fungus _Pyrenophora teres_ and affects only domestic and wild barleys (_Hordeum_ spp.). Losses of up to 20 percent to have been reported. The pathogen survives between seasons on barley residue, volunteer barley, some grasses, and seed.
For more information on net blotch see ProMED-mail post no. 20080707.2057.

Two types of mildew on barley are known, and it is not specified above which one has been observed. Powdery mildew is caused by _Blumeria_ (syn. _Erysiphe_) _graminis_ f.sp. _hordei_ and can affect all aerial parts of the plant. Losses of up to 40 percent have been recorded and are greatest when the plants are infected in the seedling stage. Downy mildew is caused by _Sclerophthora_ species and is considered a minor disease of the crop.

Scald caused by _Rhynchosporium secalis_ is one of the most destructive diseases of barley, particularly in wet seasons. It can decrease yield by up to 40 percent and reduces grain quality. The pathogen can cause symptomless seed infection, which leads to a high risk of spread.

Management strategies for these pathogens generally include cultural practices to reduce inoculum, fungicides, use of clean seed, and resistant cultivars. For more information on the diseases please see links below.

Maps of UK:
<http://www.lib.utexas.edu/maps/europe/united_kingdom.gif>  and
<http://healthmap.org/promed?v=54.5,-2,5>

Pictures
Net blotch:
<http://plantpathology.tamu.edu/Texlab/Grains/Barley/Images/barley1.jpeg>  and <http://www.inra.fr/hyp3/images/6034311.jpg>
Powdery mildew:
<http://farm1.static.flickr.com/135/329149435_c5eacc3831.jpg?v=0
http://www.ppws.vt.edu/stromberg/smallgrain/image/bpmildew.gif>
Scald:
<http://www.inra.fr/hyp3/images/6035961.jpg>  and <http://www.blackthornarable.co.uk/photography/cereals/disease/D_0969.jpg>

Links
Information on net blotch of barley:
<http://www.inra.fr/hyp3/pathogene/6pyrter.htm> and <http://www.ipm.ucdavis.edu/PMG/r730100311.html>
_P. teres_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=255071>
Powdery mildew information:
<http://www.sac.ac.uk/consultancy/services/c-e/cropclinic/clinic/diseases/barleymildew>,
<http://www.hannafords.com/disease.php?id=10>  and <http://www.ppws.vt.edu/stromberg/smallgrain/biology/bpmildew.html>
_B. graminis_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=309596>
Downy mildew information:
<http://www.ipm.uiuc.edu/diseases/series100/rpd122/index.html>
_Sclerophthora_ species list and taxonomy via:
<http://www.indexfungorum.org/Names/Names.asp>
_Rhynchosporium_ scald information:
<http://www.scri.ac.uk/research/pp/pestanddisease/rhynchosporiumonbarley>,
<http://www.inra.fr/hyp3/pathogene/6rhysec.htm>  and
<http://article.pubs.nrc-cnrc.gc.ca/RPAS/rpv?hm=HInit&journal=tcjpp&volume=23&afpf=k01-029.pdf>
_R. secalis_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=102367>
List of barley diseases:
<http://www.apsnet.org/online/common/names/barley.asp>
Syngenta UK:
<http://www.syngenta.co.uk/>.  - Mod.DHA]

[see also in the archive:
2008
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Downy mildews, maize, grapevine - India 20081110.3537 Cereal diseases - Australia, UK, USA 20080707.2057 Fungal diseases, cereals - UK, Ireland: update 20080428.1460 Fungal pathogens, wheat - UK (England) 20080319.1055
2004
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Barley net blotch, spot type - Uruguay: 1st report 20041130.3198]