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: Fri 12 Oct 2018 11:36 UTC
Source: S&P Global [edited]
<https://www.spglobal.com/platts/en/market-insights/latest-news/agriculture/101218-black-leaf-spot-disease-will-hurt-sugar-beet-yields-in-france-warns-le-betteravier>
Black leaf spot, or cercospora, disease will hurt sugar beet yields in France, affecting sugar beet "particularly strongly this year [2018]."
[It] can result in significantly reduced yields and quality, and reduces storability of sugar beet roots in piles.
European sugar beet production is already forecast to be lower during the current 2018-19 campaign due to hot and dry weather, with France's agriculture ministry cutting its sugar beet production estimates down 13 per cent. [With] the impact of cercospora, yields could be revised down further.
ITB's [Institut Technique de la Betterave] Alexandre Quillet said that it is "everywhere, even in Normandy. Cool and humid conditions in the morning and then hot in the afternoon are ideal conditions to encourage cercospora." The current campaign [is described] as "decidedly difficult" for farmers.
[Byline: Thomas Wigglesworth]
--
Communicated by: ProMED-mail <promed@promedmail.org>
[Leaf spot caused by _Cercospora beticola_ is the most destructive foliar diseases of beet crops in warm and humid growing areas. It affects most species of _Beta_ (cultivated and wild) and also many weed species in the Amarantaceae and Chenopodiaceae families which can serve as pathogen reservoirs. Symptoms on sugar beet (_Beta vulgaris_) include circular leaf spots with characteristic black centres that coalesce and, in severe cases, can lead to complete leaf collapse.
During severe outbreaks, new leaf growth can be seen emerging from the centre of collapsed leaves. The disease reduces photosynthetic ability of the plant and, therefore, yield and quality of beet crops.
Disease management generally relies on fungicides, but resistant _C.
beticola_ strains are emerging. For example, a strobilurin resistant strain has recently been reported from the UK (ProMED-mail post http://promedmail.org/post/20170413.4967611]. Rotating or mixing chemical classes of fungicides is used to extend the useful life of individual compounds. Partial genetic resistance to the pathogen in some _Beta_ varieties is used in breeding programmes to develop new crop cultivars.
Leaf spot diseases on a range of crops (such as peanut, soybean, coffee, maize) can be caused by other fungi previously classified as _Cercospora_ species. While some of them have since been attributed to different genera, the diseases are often still referred to as cercospora leaf or eye spots.
Maps
France:
<https://image.shutterstock.com/z/stock-vector-france-political-map-with-capital-paris-national-borders-most-important-cities-and-rivers-218333659.jpg>
and
<http://healthmap.org/promed/p/100>
Pictures
Cercospora symptoms on beet leaves:
<https://c1.staticflickr.com/9/8606/15636366963_d0b6a16854_b.jpg>,
<http://goo.gl/m0vpSx>, and
<https://goo.gl/qgbgek>
Cercospora leaf spot, symptoms on whole beet plant:
<http://goo.gl/NeRFev> and
<http://goo.gl/U159QM>
Comparison of cercospora with other leaf spot diseases:
<http://extensionpublications.unl.edu/assets/html/g1753/build/graphics/g1753-2.jpg>
Cercospora affected beet fields:
<https://www.ag.ndsu.edu/cpr/images/09-15-16/ppth-1-2.png> and <http://goo.gl/e21MIe>
Links
Cercospora leaf spot information:
<http://www.bspp.org.uk/publications/molecular-plant-pathology/pathprofiles/pathprofile38.htm>,
<http://www.ipm.ucdavis.edu/PMG/r735100511.html> and <http://cropwatch.unl.edu/plantdisease/sugarbeet/cercospora-leaf-spot>
_C. beticola_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=162050>
Species and taxonomy of genus _Beta_:
<http://www.plantnames.unimelb.edu.au/Sorting/Beta.html>
ITB:
<http://www.itbfr.org/in-english/>
- Mod.DHA]
[See Also:
2017
----
Cercospora leaf spot, sugar beet - UK: strobilurin resistance
http://promedmail.org/post/20170413.4967611
2012
----
Cercospora leaf spot, sugarbeet - USA: (MI,ND) new strains
http://promedmail.org/post/20120216.1043062
2010
----
Cercospora leaf spot, sugarbeet - UK: alert
http://promedmail.org/post/20100709.2297
2007
----
Cercospora & powdery mildew, sugar beet - UK
http://promedmail.org/post/20070801.2478
and additional items on cercospora diseases in the archives]
Topics
Species
