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Fusarium wilt on lettuce in the Netherlands


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: Mon 19 Oct 2015
Source: FreshPlaza [edited]
<http://www.freshplaza.com/article/147107/Fusarium-ruins-Dutch-lettuce-production>

Fusarium ruins Dutch lettuce production

Lately, a persistent soil fungus has gained ground in the Dutch

greenhouses: fusarium. This disease is found in many open-field crops and has already caused a lot of damage in Italy, Japan, and the United States. [A] grower acknowledges that the lettuce sector now has quite a problem. "Some growers had to throw away nearly their entire harvest. We are working hard on finding a solution."

According to Ruud van Amersfoort of Horti-Consult Int., the Netherlands is only really starting to feel the problems with fusarium

now: 8 [grower] companies have been seriously infected. At half of these companies, growing butterhead lettuce is economic suicide. The acreage involved is about 8.5 ha. He says a few of them have stopped growing butterhead lettuce in summer. "One grower, for instance, has swapped 3 ha with a radish grower, because the radish isn't affected by the disease. [For] the remaining companies, steaming [of soil] [is taking] place. [One] grower is having his entire 3 ha steamed, which means he will be out of action for 7 weeks."

For now, prevention seems to be the only method: "With 70 per cent of acreage affected, the grower has to switch to a different crop. The greenhouse becomes so heavily affected that steaming probably isn't a solution anymore. Work will have to be done very hygienically, spraying off tillage and planting machines [and] all materials in the greenhouse," Ruud says. "The lettuce sector needs to ask itself if they haven't overcropped their land in recent years. This, as well as monoculture, facilitates diseases."

[Byline: Arnaud-Jan de Braal]

--

Communicated by: Dr G Jackson, Moderator, PestNet <http://www.pestnet.org>

[Fusarium wilt of lettuce is caused by the fungus _Fusarium oxysporum_ f.sp. _lactucae_ (synonym _lactucum_). Symptoms include leaf yellowing, tip burn and necrosis, as well as browning of vascular tissues and rotting of the tap root. Plants of any age are susceptible. They 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 per cent 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 temperatures. Once introduced to an area, the 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.

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, as mentioned above) to avoid spread to new fields. For related fusarium pathogens, flooding of fields has been reported to reduce fungal survival in the soil.

In Europe, the disease was reported for the 1st time from northern Italy in 2001 (ProMED-mail post 20020821.5103).

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 pathovar is highly specialised attacking only a single crop species.

 

Maps

Netherlands:

<http://www.ezilon.com/maps/images/europe/physical-map-of-Netherlands.gif>,

<http://www.graphatlas.com/netherlands_political_map_with_counties.jpg>,

and

<http://healthmap.org/promed/p/104>

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>,

and

<http://ag.arizona.edu/plp/plant-images/plant11.jpg> (affected field) Symptoms on taproots:

<http://ucanr.org/blogs/SalinasValleyAgriculture/blogfiles/6898.jpg>

and

<http://thegordonlab.net/wp-content//uploads/2014/02/81.jpg>

Comparison of cultivars with different levels of susceptibility:

<http://ucce.ucdavis.edu/files/repository/calag/img6601p20.jpg>

 

Links

Information on fusarium wilt of lettuce:

<http://www.ipm.ucdavis.edu/PMG/r441100911.html>,

<http://www.eppo.int/QUARANTINE/Alert_List/deleted%20files/fungi/Fusarium_oxysporum_lactucae.docx>,

<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>,

<http://californiaagriculture.ucanr.org/landingpage.cfm?article=ca.v066n01p20&fulltext=yes>,

and

<http://ag.arizona.edu/crop/vegetables/advisories/more/disease46.html>

_F. oxysporum_ f.sp. _lactucae_ taxonomy:

<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=586936>

Horti-Consult:

<http://www.horti-consult.nl/en/home/>

- Mod.DHA]

 

[See Also:

Fusarium wilt, lettuce - USA: (AZ) 20150721.3525165

2003

----

Fusarium wilt, lettuce - USA (AZ): first report 20030922.2393

2002

----

Fusarium wilt, lettuce - Europe 20020821.5103 and additional items on fusarium diseases in the archives] 



More news from: ISID (International Society for Infectious Diseases)


Website: http://www.isid.org

Published: October 22, 2015

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