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 19 May 2024 14:00 BST
Source: Farming Life [summ. Mod.DHA, edited]
https://www.farminglife.com/business/the-threat-posed-by-barley-yellow-dwarf-virus-is-changing-4633138


The enhanced threat currently posed by barley yellow dwarf (BYD) could significantly reduce the size of the cereal harvest across the island of Ireland later this year [2024].

Recent developments in the Republic of Ireland have confirmed the changing nature of the threat posed by BYD to cereal crops which is running rampant through winter and spring cereal crops at the present time.

Adding to the concern is the fact that Teagasc (Irish Agriculture and Food Development Authority) scientists don't know how the vector aphids are getting on to crops in the first place. They had not predicted these developments, since suction traps had not caught significant numbers of flying aphids over recent months.

This leaves open the possibility of grain aphides physically walking through fields and/or overwintering on individual cereal plants. This type of aphid behaviour has not been recognised previously and will be a key focus of new research within Teagasc.

In the meantime, cereal growers are being strongly advised to spray their spring barley and wheat crops with an insecticide as a matter of priority.

--
Communicated by:
ProMED

[Barley yellow dwarf (BYD) disease occurs worldwide and affects a wide range of grass species (Gramineae) including cereal crops like barley, wheat, oats, rice, maize, triticale (wheat-rye hybrids) and rye. It is the most destructive of the virus diseases for wheat, but oats are particularly susceptible. Grain yields may be reduced severely. Symptoms include leaf discolouration from yellow to purple (depending on the host species), stunting, reduced tillering and empty seed heads. Yield reduction is most severe if infection occurs at the seedling stage. Plants infected in autumn may not survive the winter or show severe symptoms when growth resumes. Diseased plants often occur in circular patches within a field, which are associated with colonisation by the aphid vectors.

BYD viruses have now been split into several species in the family Luteoviridae (mostly in the genus _Luteovirus_). They are differentiated by their ability to be transmitted by various aphid species (family Aphididae) and their virulence on a selected variety of oats. Some of the viruses are transmitted equally well by several aphids, whereas others can be transmitted by only 1 or 2 species. The bird cherry(-oat) aphid (_Rhopalosiphum padi_) and (English) grain (wheat) aphid (_Sitobion avenae_) are vectors of the severe _Barley yellow dwarf virus-PAV_ (type member of genus _Luteovirus_). Coinfections of several BYD viruses may occur in one plant, which can result in either more severe (synergistic) or milder (due to cross protection) symptoms, depending on the virus partners.

The viruses cannot be transmitted by seed, pollen or mechanical means; they cannot survive in stubble or in the soil. Volunteer cereal plants or grassy weeds may serve as pathogen reservoirs ("green bridge"). Disease management includes use of crop cultivars with reduced sensitivity to the viruses and control of the aphid vectors.

Pictures
BYD symptoms on cereals
- barley:
https://image.slidesharecdn.com/r-180626054804/95/barley-yellow-dwarf-disease-15-638.jpg
- wheat:
https://www.ent.iastate.edu/imagegal/plantpath/wheat/ydwarf/0093.04ydwarfmv.html (compared with healthy),
https://img.yumpu.com/46899655/1/358x269/barley-yellow-dwarf-symptomspdf.jpg and
https://www.ent.iastate.edu/images/plantpath/wheat/ydwarf/0093.10ydwarfwheat.jpg (affected field)
- oats:
https://site.extension.uga.edu/brooksag/files/2015/02/20150203_124826.jpg,
https://site.extension.uga.edu/brooksag/files/2015/02/20150203_124840.jpg,
https://oatnews.org/sites/default/files/BarleyYellowDwarf04.jpg and
https://www.nexles.com/articles/wp-content/uploads/2018/05/oat-avena-sativa-Barley-yellow-dwarf-virus.jpg
Aphids:
https://d1o50x50snmhul.cloudfront.net/wp-content/uploads/2013/11/dn24513-1_800.jpg and
https://ohioline.osu.edu/sites/ohioline/files/imce/Plant_Pathology/PLPTH-CER-01_wheat-aphid-infestation.png

Links
BYD disease and virus information:
https://grdc.com.au/resources-and-publications/all-publications/factsheets/2013/09/barley-yellow-dwarf-virus,
https://doi.org/10.1079/cabicompendium.10539,
https://www.apsnet.org/edcenter/disandpath/viral/pdlessons/Pages/BarleyYelDwarf.aspx,
https://ohioline.osu.edu/factsheet/plpath-cer-01,
https://cropwatch.unl.edu/plantdisease/wheat/barley-yellow-dwarf,
https://site.extension.uga.edu/brooksag/2015/02/oats-barley-yellow-dwarf/ and
http://www.herbiguide.com.au/Descriptions/hg_Barley_Yellow_Dwarf_Virus_of_Oats.htm
BYD disease cycle:
https://image.slidesharecdn.com/r-180626054804/95/barley-yellow-dwarf-disease-21-638.jpg
Virus taxonomy via:
https://ictv.global/taxonomy
Information on aphid vectors via:
https://bugguide.net/node/view/63
- Mod.DHA]

See Also

2022
----
Barley yellow dwarf - Ireland 20220603.8703653
2020
----
Barley yellow dwarf, cereals - Australia: (VI) 20201020.7874764
Barley yellow dwarf, oat - USA: (SD) 20200616.7473516
2019
----
Barley yellow dwarf, cereals - UK: control 20190920.6684232
2018
----
Barley virus G - Australia: 1st rep (VI) 20181126.6166030
2017
----
Barley yellow dwarf, cereals - UK, Canada 20170818.5257933
Barley yellow dwarf - Ireland: (WX) 20170609.5094454
2016
----
Barley yellow dwarf, cereals - UK 20161011.4550142
2015
----
Barley yellow dwarf, wheat - Denmark 20150622.3455679
Barley yellow dwarf, cereals - USA: (ID) alert 20150404.3276394
2014
----
Barley yellow dwarf virus-PAS, wheat - Turkey 20140616.2543025
and older items in the archives

Website: http://www.isid.org

Published: June 11, 2024