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: Thu 12 May 2016
Source: FG Insight [edited]
<https://www.fginsight.com/news/highly-resistant-septoria-identified-in-wheat-seedling-tests-12129>
Latest septoria monitoring results confirm the presence in the UK of isolates with a high level of resistance to SDHIs [succinate dehydrogenase inhibitor fungicides]. The results from tests on susceptible seedlings in a glasshouse are in line with laboratory findings reported by AHDB [Agriculture and Horticulture Development Board] earlier.
A small number of septoria tritici isolates collected in the UK in 2015 have been confirmed as being highly resistant. The work also confirmed the presence of mutations in the three genes involved in the binding of SDHIs to their target site.
The frequency of these highly resistant isolates was extremely low in the UK population in 2015. Although good control of septoria from SDHIs is still anticipated in 2016, the ability of these new highly resistant mutated strains to survive and increase is a considerable cause for concern.
Dr Paul Gosling, AHDB, says: "The latest results are toward the worst end of our expectations. They confirm, more than ever, that it is critical to adopt best resistance management practices to slow the spread of these strains and maximise the effective lifespan of the SDHIs."
[Byline: Teresa Rush]
--
Communicated by:ProMED-mail <promed@promedmail.org>
[Septoria leaf blotch of cereals is caused by fungi in the septoria species complex which includes _Zymoseptoria tritici_ (previously _Septoria tritici_) , _Mycosphaerella graminicola_ and _Phaeosphaeria nodorum_ (previously _Stagonospora nodorum_). They affect mainly wheat, but also barley and oats and occasionally rye and some grass species. Symptoms on wheat and barley are very similar and may occur at any time during the growth of the plant and on any portion of the plant. They include blotches on both leaves and glumes which reduce the photosynthetic ability of the host. Up to 50 per cent yield losses have been reported on susceptible varieties.
Spores can be spread by infected plant material, wind, water (rain splash) and mechanical means. The pathogens can overwinter on crop debris and on autumn sown crops or volunteers. Disease management includes fungicide treatments aimed at preventing the disease becoming established on the upper 3 leaves of the crop canopy, removal of inoculum sources and use of resistant varieties. Septoria is considered the most important foliar disease of winter wheat in the UK and other parts of Europe where it has evolved high levels of resistance to many fungicides. After the cereal rusts, the disease is considered the most important challenge to plant breeders (see ProMED-mail post http://promedmail.org/post/20120831.1274190) and a threat to food security worldwide.
While SDHI fungicides are not new, their previous limited use meant that resistance under commercial conditions remained limited to a few pathogens and crops. A "2nd generation" of SDHIs is currently being used to combat fungal diseases that have developed resistance to other groups of fungicides.
In the UK, SDHI resistance was confirmed for the 1st time in 2014 in barley net blotch (_Pyrenophora teres_) and an alert was issued for the possible emergence of SDHI resistance of septoria pathogens (ProMED-mail post http://promedmail.org/post/20140507.2457504). SDHI resistant septoria strains were reported for the 1st time in Ireland in 2015 (ProMED-mail post http://promedmail.org/post/20151214.3860515). The strains in the UK are being reported to carry the same mutations as detected in Ireland (see link below) which raises the question of whether they may have spread to the UK from there.
Maps
UK:
<http://www.lib.utexas.edu/maps/europe/united_kingdom.gif> and <http://www.picturesofengland.com/images/mapofengland/england-counties.gif>
Europe, overview:
<http://www.youreuropemap.com/europe_map_political.gif>
Pictures
Wheat crop affected by septoria:
<https://www.agric.wa.gov.au/sites/gateway/files/styles/original/public/septoria_nodorum_withered_leaves.jpg?itok=-ZWZPjFM>
Septoria leaf symptoms:
<http://ipm.illinois.edu/bulletin/photos/septoria_wheat.jpg>,
<http://www.abgenternasyonel.com/images/icerik/septoria%20tritici.jpg>
and
<http://www.apsnet.org/edcenter/intropp/lessons/fungi/ascomycetes/Article%20Images/SeptoriaTriticiBlotch01.jpg>
Septoria symptoms on wheat ear:
<http://www.omafra.gov.on.ca/english/crops/pub811/images/6septf2.jpg>
Septoria on resistant and susceptible wheat varieties:
<http://www.fao.org/docrep/006/y4011e/y4011e1d.jpg>
Septoria diseases and pathogens, photo gallery:
<http://www.forestryimages.org/browse/subimages.cfm?sub=9457>
Links
Additional news stories:
<http://www.scotsman.com/business/companies/farming/wheat-growers-must-act-now-over-disease-threat-1-4127054>
<http://www.fwi.co.uk/arable/septoria-crosses-east-west-wheat-disease-divide.htm>
Information on septoria diseases:
<http://www.agroatlas.ru/en/content/diseases/Tritici/Tritici_Septoria_tritici/>,
<http://www.agroatlas.ru/en/content/diseases/Tritici/Tritici_Septoria_nodorum/>,
<http://www.apsnet.org/edcenter/intropp/lessons/fungi/ascomycetes/Pages/Septoria.aspx>
and
<http://cereals.ahdb.org.uk/cereal-disease-encyclopedia/diseases/septoria-leaf-blotch.aspx>
(incl. life cycle)
AHDB analysis of UK strains:
<http://cereals.ahdb.org.uk/press/2016/february/12/sdhi-fungicide-sensitivity-shift-detected-in-two-uk-septoria-isolates.aspx>
Taxonomy of fungal species via:
<http://www.indexfungorum.org/Names/Names.asp>
Information on SDHI fungicides:
<http://www.nzpps.org/journal/64/nzpp_641190.pdf>
- Mod.DHA
A HealthMap/ProMED-mail map can be accessed at:
<http://healthmap.org/promed/p/40>.]
[See Also:
Fungal diseases, wheat & oilseed rape - UK: alert
http://promedmail.org/post/20160128.3971413
2015
----
Septoria blotch, wheat - Europe (02): (Ireland) new strains, SDHI resistance http://promedmail.org/post/20151214.3860515
Septoria blotch, wheat - Ethiopia: survey of incidence
http://promedmail.org/post/20151018.3725790
Septoria blotch, wheat - Europe: fungicide resistance
http://promedmail.org/post/20150619.3450044
2014
----
Fungal diseases, cereal crops - UK: SDHI resistance, alert
http://promedmail.org/post/20140507.2457504
Septoria blotch, wheat - New Zealand: new strains, strobilurin resistance http://promedmail.org/post/20140417.2410219
Septoria, wheat - Australia: new strains, alert
http://promedmail.org/post/20140313.2329774
2011
----
Fungal diseases, cereal crops - Ireland: alert
http://promedmail.org/post/20110525.1590
2010
----
Fungal diseases, cereals - Australia: alert
http://promedmail.org/post/20100825.2989
Fusarium head blight & stagonospora, wheat - USA: (OH)
http://promedmail.org/post/20100708.2277
Septoria, wheat & barley - France: (BN)
http://promedmail.org/post/20100517.1608
Fungal diseases, cereals - Germany: (SN)
http://promedmail.org/post/20100428.1370
Net blotch, barley - Australia: (SA) new strains, alert http://promedmail.org/post/20100323.0921]
Topics
Species
