Date: 25 March 2007
From: ProMED-mail <promed@promedmail.org>
From: Farmers Weekly Interactive [edited]
http://www.fwi.co.uk/Articles/2007/03/23/102540/mosaic-virus-alert-for-barley-growers.html>

Mosaic virus alert for British barley growers

Barley growers should inspect crops for signs of mosaic virus, as higher than normal levels have been seen in crops this season, according to Nickerson. "Symptoms in non-resistant varieties are the strongest we have seen for many years," said the firm's plant pathologist, Paul Fenwick. "The mild winter means there's a lot more leaf area to be affected, so the virus is much more visible."

Once the weather warmed up, many crops would grow away from the virus, but badly affected areas may suffer a 30-40 percent yield penalty, he said. "If you've got it, there's no chemical control, so the only option is to sow resistant varieties." The virus lives in the soil and persists for 15-20 years, he added. It is a particular problem in colder seasons and areas where barley features heavily in the rotation, such as the Cotswolds, he noted.

[Byline: Paul Spackman]

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[Although the report is on "barley mosaic virus," this virus has only been recorded in India; see Plant Viruses Online: <http://image.fs.uidaho.edu/vide/descr060.htm>.

The virus reported here is most likely barley mild mosaic virus (BaMMV); see Plant Viruses Online:
<http://image.fs.uidaho.edu/vide/descr059.htm>, which is spreading in Belgium, France, Germany, Italy, Japan, the Netherlands, and the UK. Symptoms vary seasonally (found in winter or early spring only), and in barley, they include yellow streaks, especially on younger leaves and sometimes on the leaf sheath, and also brown necrotic patches. Leaves may roll, making the plant look "spiky." Transmission by a fungal vector (_Polymyxa graminis_) accounts for its persistence in soil. It is also transmitted by mechanical inoculation but is not transmitted by contact between plants, by seed or by pollen.

Pictures: <http://www.rothamsted.ac.uk/ppi/staff/kostya/viral_pathogenesis.html>

- Mod.DHA]

[see also in the archive:

2005
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Barley yellow mosaic - Spain: 1st report: correction 20050112.0101 Barley yellow mosaic - Spain: 1st report 20050111.0094