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: 18 September 2008
Source: FarmingUK [edited]
<http://www.farminguk.com/news/Ringspot-capture-signals-high-risk-looming8602.asp>

Ringspot capture signals high risk looming

Disease pressure is building on brassica crops, with significantly high levels of ringspot spores being picked up in monitoring traps across east Lincolnshire, reports Andy Richardson of the Allium and Brassica Centre.

The capture of high levels of spores in several traps, combined with weather conducive to infection indicates a high risk of infection in these areas. "Any crops that have not received a suitable fungicide in the past 14 days should be treated as soon as possible," advises Mr Richardson.

Furthermore, white blister remains at high risk, as a consequence of extended periods with wet leaves. Crops must be regularly inspected and treated at the 1st signs of disease, he adds.

--
Communicated by:
ProMED-mail
<promed@promedmail.org>

[Ringspot disease on _Brassica_ crops is caused by the fungus _Mycosphaerella brassicicola_. Symptoms are small dark spots on leaves, which become larger lesions with concentric rings of growth and a definite margin. Disease development is favoured by warm, humid conditions. The pathogen is spread by splashing water, mechanical means and insects and overwinters in plant debris and biennial seed crops. In the UK, fungal ringspot has become more damaging to brassica crops in recent years especially in Cornwall and Lincolnshire. The disease is managed mainly by timely fungicide applications.

Spore traps are used for determining identity and time of dispersal of fungi. Spores can be identified by morphology to genus and sometimes species. They can indicate the presence of a fungal pathogen before disease is discovered in the field because symptoms need time to develop and may initially be difficult to detect. Number of spores and environmental conditions are used for risk assessment of crop damage by a certain fungus.

White blister is caused by the fungus _Albugo candida_ and affects most plants of the brassica (or crucifer) family. Disease management includes phytosanitation, cultural practices, and fungicides. For more information on this disease please see previous ProMED-mail post no. 20080218.0661.

Maps
UK
<http://www.lib.utexas.edu/maps/europe/united_kingdom.gif> and <http://healthmap.org/promed?v=53.167,-0.25,5>
Lincolnshire:
<http://www.touristnetuk.com/em/lincolnshire/images/map.gif>  and <http://en.wikipedia.org/wiki/Image:EnglandLincolnshire.png>


Pictures
Fungal ringspot on cabbage leaves:
<http://www.bitkisagligi.net/Crucifer/cruciferresim/Mycosphaerella%20brassicicola-5.jpg>
and
<http://mtvernon.wsu.edu/path_team/Aug03Photos/Image26.jpg>
White blister on brassicas:
<http://www.shootgardening.co.uk/uploaded/images/plant_disease_20051204160354.jpg>
and
<http://www.hri.ac.uk/site2/research/path/blister.jpg>

Links
Information on fungal pathogens of brassicas, including ringspot:
<http://www.hri.ac.uk/site2/research/path/pathogen.htm>  and <http://mtvernon.wsu.edu/path_team/newsaug03.htm>
_M. brassicicola_ strains:
<http://www.springerlink.com/content/nl331844428u58t3/>
_M. brassicicola_ taxonomy:
<http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=100064>
Information on white blister of brassicas:
<http://www.growcom.com.au/_uploads/22331white_blister_handout.pdf>
White blister and other foliar fungal pathogens of brassicas:
<http://www.hri.ac.uk/site2/research/path/pathogen.htm>
_A. candida_ taxonomy:
<http://www.indexfungorum.org/Names/SynSpecies.asp?RecordID=122113>
Information on spore traps:
<http://www.weld.co.za/PDF/Flyer_VST.pdf> and <https://www.emlab.com/media/reports/STstandard.pdf>
Allium & Brassica Centre:
<http://www.abcentre.co.uk>.  - Mod.DHA