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Viruses - Barley

Contributors to this section: ICARDA, Syria (Siham Asaad, Abdulrahman Moukahal).

Contents:
Barley Stripe Mosaic Virus (BSMV)
Barley Mosaic Virus (BMV)
Wheat Streak Mosaic Virus (WSMV)

Barley Stripe Mosaic Virus (BSMV)

Other scientific names

Barley False Stripe Virus, Possibly Barley Yellow Stripe Virus, Barley Mild Stripe Virus, Oat Stripe Mosaic Virus.

Disease name

Barley Stripe Mosaic.

Importance

Seedborne.

Significance

Yield losses are proportional to the level of infection in the seed lot. Heavily infected crops have had yield reductions of up to 25%. The percentage of infected seedlings indicates the level of grain infection.

Symptoms

Yellow to white mosaic, spotting and necrotic stripes.

BSMV on the right (source: Bugwood.org)

Hosts

Natural hosts are members of the Gramineae, but species of Chenopodiaceae and Solanaceae can be experimentally infected.

Geographic distribution

ASIA: Israel, Japan, Jordan, Pakistan; AUSTRALASIA and OCEANIA: Australia (Victoria), EUROPE: Bosnia & Herzegovina, Britain (England), Croatia, Denmark, France, Germany, Kosovo, Macedonia (FYR), Montenegro, Norway, Romania, Russian Federation, Serbia, Slovenia; NORTH AMERICA: Canada, USA; SOUTH AMERICA: Argentina.

Biology and transmission

Transmitted by means not involving a vector. Virus transmitted by mechanical inoculation; transmitted by seed (up to 90-100%); transmitted by pollen to the pollinated plant.

The virus is seedborne and is transferred from plant to plant when the crop leaves rub against one another. Experimentally the virus can be transmitted by pollen, but since barley is self-pollinated this method of spread is generally of no consequence. Infected seeds produce infected plants. Seed from virus-infected plants is generally infected to a 60% level.

Detection/indexing method in place at ICARDA

Treatment

Procedure followed at the CGIAR Centres in case of positive testing at ICARDA

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Barley Mosaic Virus (BMV)

Significance

Not significant.

Symptoms

The Barley Mosaic Viruses are usually first noticed in the winter or early spring as yellow patches in the crop. They causes mosaic and stunting.

BMV typical symptoms on younger leaves (photo: rothamsted.ac.uk)

Hosts

Avena sativa, Hordeum vulgare, Triticum aestivum.

Geographic distribution

India and Japan.

Biology and transmission

Virus is transmitted by aphids: Rhopalosiphum maidis and by mechanical inoculation; transmitted by seeds.

Detection/indexing method in place at the CGIAR Centres

Treatment/control

References and further reading

http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.079.0.70.003.htm

http://www.apsnet.org/online/common/names/barley.asp

http://www.rothamsted.ac.uk/ppi/staff/mja.html

Seed Health General Publication published by the Centre or the CGIAR.

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Wheat Streak Mosaic Virus (WSMV)

Importance

Seedborne.

Significance

Early widespread infection of young wheat plants (approaching 100% infection) is generally associated with greatest yield losses from Wheat Streak Mosaic Virus (WSMV) and can cause complete crop failure, as such crops produce only small amounts of shrivelled grain. Patchy, early infection can also cause substantial yield losses within the affected crop area.

Symptoms

The symptoms of WSMV in wheat appear as pale green streaking on leaves, yellowing of the older leaves (especially towards their tips) and stunted, tufted plant growth. Affected plants become stunted compared to healthy plants when they are infected at an early growth stage (pre-tillering) but this stunting symptom is much less obvious with later infection. Heads on early infected, stunted plants are either sterile and contain no seed, or contain small shrivelled grain. Except for volunteer oats, no symptoms have been seen in Western Australia on WSMV-infected alternative hosts (grasses and barley).

Yellowing of the older leaves (photo: coopext.colostate.edu)

Hosts

Avena sativa, Hordeum vulgare, Poa compressa, Secale cereale, Triticum aestivum and Zea mays.

Geographic distribution

The virus occurs in the Canada, United States, Jordan, Eastern Europe and Russian Federation.

Biology and transmission

Infections first appear at the margins of a field because of the movement of the virus’s mite vector. Infections may occur in the winter, but symptoms often do not appear until the spring temperatures rise to above 10°C.

Transmitted by a vector; a mite; wheat curl mite (WCM) Aceria tulipae; Eriophyidae. The virus is not transmitted congenitally to the progeny of the vector; transmitted by mechanical inoculation; not transmitted by contact between plants; transmitted by seed (very low levels).

Detection/indexing method in place at the CGIAR Centers

Treatment

Procedure in case of positive test

Not applicable.

References and further reading

http://wheatdoctor.cimmyt.org/index.php?option=com_content&task=view&id=186&Itemid=43

http://www.agroatlas.ru/en/content/diseases/Tritici/Tritici_Wheat_streak_mosaic_rymovirus/

http://www.coopext.colostate.edu/TRA/Agronomy/HighPlains/hpd.figure2.jpg

http://www.dpi.nsw.gov.au/research/updates/issues/july-2006/wsmv-under-scrutiny

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The Genebanks

The 11 CGIAR genebanks currently conserve 730,000 of cereals and grain legumes, forage crops, tree species, root and tuber crops, bananas and crop wild relatives.

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