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: Wed 5 Sep 2018
Source: Fruitnet [edited]
<http://www.fruitnet.com/fpj/article/176530/new-lettuce-fusarium-wilt-outbreak-confirmed>
New outbreaks of the devastating disease fusarium wilt in lettuce crops have been reported in Lancashire, Cambridge, and Ireland [see link below]. The AHDB [UK Agriculture and Horticulture Development Board] confirmed the new cases, warning that the disease was now spreading. All the cases found were in protected lettuce crops grown in greenhouses. They called on growers to help prevent spread by implementing good crop hygiene and seeking early diagnosis if they suspect it.
Kim Parker, AHDB, said, "The effective use of techniques to detect the strain of the disease identified in the UK -- lettuce fusarium wilt race 4 -- has provided the opportunity for prompt disease diagnosis."
The University of Warwick has used conventional and molecular techniques to detect presence of the disease. Trials are currently underway to test the impact of plant protection products on the disease. New work will start to find out more about the biology of lettuce fusarium wilt.
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Communicated by: ProMED-mail <promed@promedmail.org>
[Fusarium wilt of lettuce caused by the fungus _Fusarium oxysporum_ f.sp. _lactucae_ (FOL) can affect plants of any age. Symptoms include leaf yellowing, tip burn and necrosis, as well as browning of vascular tissues and rotting of the tap root. Plants may be stunted and fail to form heads; infected seedlings wilt and may die. Disease incidence can range from a few plants up to large areas within a field.
The pathogen occurs in soils worldwide and is commonly found on roots of healthy plants. Most strains cause no damage to their hosts, but severe strains can block the water-conducting xylem and lead to wilting. Three races are known to cause disease in lettuce, with up to
70 percent crop losses reported. Lettuce cultivars have been reported to differ significantly in susceptibility, with some leaf and romaine types highly resistant. Disease severity may also depend on fungal populations in the soil, inoculum levels, and temperature.
Spread occurs mainly on contaminated seed, with soil, infected crop debris, irrigation water, and human activities (for example on farm machinery and tools). Disease management requires an integrated approach including crop rotation and phytosanitary measures (including steam treatment of soil) to avoid spread to new fields. For related fusarium pathogens, flooding of fields has been reported to reduce fungal survival in the soil. Once introduced to an area, FOL fungi may survive indefinitely on the roots of asymptomatic reservoir hosts.
Thus, resistant lettuce varieties and rotation crops can contribute to an increase in soil inoculum. Race 4 is particularly aggressive; no chemical treatments or resistant lettuce varieties are known for it so far.
In Ireland, 2 sites seem to have been confirmed (County Dublin area) and 2 further sites suspected (see link below). In the UK, FOL was reported for the 1st time in late 2017 (ProMED-mail post
http://promedmail.org/post/20171030.5412370) in Lancashire.
Different strains of the fungus cause wilting diseases with serious losses in other crops, such as banana (Panama disease), guava, vanilla, date palm, and a range of cucurbits. Each of the pathovars is highly specialised, attacking only a single crop species.
Maps
Ireland:
<http://www.vidiani.com/maps/maps_of_europe/maps_of_ireland/general_map_of_ireland.jpg>
UK:
<http://www.lib.utexas.edu/maps/europe/united_kingdom.gif> (with
counties)
Europe, overview:
<http://www.edinphoto.org.uk/0_MAPS/0_map_europe_political_2001_enlarged.jpg>
Pictures
Fusarium wilt on lettuce plants:
<http://people.umass.edu/jmeagy/Lettuce-fusarium%20wilt.jpg>
<http://ucanr.edu/blogs/anrnews/blogfiles/5375.jpg>
<http://ag.arizona.edu/crop/vegetables/advisories/images/FusariumSymptoms.jpg>
<http://ag.arizona.edu/plp/plant-images/plant11.jpg> (affected field) Symptoms on taproots:
<http://ucanr.org/blogs/SalinasValleyAgriculture/blogfiles/6898.jpg>
<http://thegordonlab.net/wp-content//uploads/2014/02/81.jpg>
Links
First report of FOL in Ireland:
<https://horticulture.ahdb.org.uk/sites/default/files/CP1718-1006_Technical%20review%20on%20Lettuce%20Fusarium%20wilt%20PDF.pdf>
Additional news stories:
<http://www.thatsfarming.com/news/crop-disease-confirmed>
<https://www.agriland.co.uk/farming-news/new-cases-of-lettuce-fusarium-wilt-confirmed-in-uk/>
<http://www.hortidaily.com/article/45413/Lettuce-Fusarium-wilt-confirmed-at-new-sites-in-the-UK>
<https://horticulture.ahdb.org.uk/news-item/lettuce-fusarium-wilt-confirmed-new-sites-uk>
<https://www.farminguk.com/news/New-outbreaks-of-devastating-crop-disease-confirmed-in-UK_50182.html>
Information on fusarium wilt of lettuce:
<https://gd.eppo.int/taxon/FUSALC>
<https://horticulture.ahdb.org.uk/lettuce-fusarium-wilt-and-root-rot>
<https://www.teagasc.ie/media/website/crops/horticulture/vegetables/Lettuce_Fusarium_Wilt_TN.doc>
<http://www.ipm.ucdavis.edu/PMG/r441100911.html>
<http://www.cals.arizona.edu/crop/presentations/2003/matheron120303.pdf>
<http://onlinelibrary.wiley.com/doi/10.1111/ppa.12135/abstract>
<http://www.calgreens.org/control/uploads/Gordon_-_Fusarium_wilt_of_lettuce.pdf>
_F. oxysporum_ f.sp. _lactucae_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=586936>
- Mod.DHA]
[See Also:
Fusarium wilt, lettuce - UK: (England)
http://promedmail.org/post/20180618.5861084
2017
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Fusarium wilt, lettuce - UK: 1st rep
http://promedmail.org/post/20171030.5412370
2015
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Fusarium wilt, lettuce - Netherlands
http://promedmail.org/post/20151022.3734467
Fusarium wilt, lettuce - USA: (AZ)
http://promedmail.org/post/20150721.3525165
2003
----
Fusarium wilt, lettuce - USA (AZ): first report
http://promedmail.org/post/20030922.2393
2002
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Fusarium wilt, lettuce - Europe
http://promedmail.org/post/20020821.5103
and additional items on fusarium diseases in the archives]
Topics
Species
