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Late blight on potato and tomato in Florida, USA and Ireland

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A ProMED-mail post
ProMED-mail is a program of the International Society for Infectious Diseases

A ProMED-mail post
<http://www.promedmail.org>
ProMED-mail is a program of the International Society for Infectious Diseases <http://www.isid.org>

[1] Potato and tomato - USA (Florida)
[2] Potato - Ireland: new strain

[1] Potato and tomato - USA (Florida)
Date: 5 Jan 2009
Source: Southeast AgNET [edited]
<http://southeastagnet.com/2009/01/05/late-blight-showing-up-in-sw-florida-crops/>

Over the weekend, reports indicate that late blight is showing up everywhere across southwest Florida on both tomato and potato. This disease can spread quickly and devastate a tomato or potato field within a few weeks if not properly controlled. Growers should scout their fields thoroughly each day, especially when cool and wet conditions conducive to disease development prevail.

Important cultural controls include destruction of cull piles, infected foliage and volunteer potato or tomato plants. Begin a spray program with fungicides if late blight is in your area or weather conditions are suitable for late blight development. Currently, fungicides are the most effective means of control until cultivars with resistance to this disease become available. Fungicides slow the rate at which the disease develops in the field. Even a short break in spray schedules can result in a dramatic increase in blight.

In Florida, it has been observed that seldom does a widespread late blight epidemic occur on tomatoes in the Manatee-Ruskin area unless the disease was present in the Immokalee area and/or Dade County.
Since late blight has been confirmed on tomato in Immokalee, growers in other areas are advised to adhere to a preventative spray program.

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

******
[2] Potato - Ireland: new strain
Date: 4 Jan 2009
Source: Sunday Times Online / Truth About Trade and Technology [edited]
<http://www.truthabouttrade.org/content/view/13083/54/>

The disease that wiped out the potato crop in the mid-19th century, causing more than one million deaths, is posing a renewed menace after a more aggressive strain has arrived, according to a leading scientist. This has prompted experts to intensify work, including using GM technology, to find a blight-resistant variety.

Dr Ewen Mullins, a research officer with Teagasc, the agriculture and food development authority, said the risk of blight has become more serious. He said: "We have humid summers, and the past 2 years have seen outbreaks of blight, probably the worst on record. A new strain has come in. It migrated westward across Europe, probably in the past 12 to 18 months. It was in the UK about 2 years ago and in the eastern counties of Ireland in 2008. It's a highly aggressive strain." The new strain can survive in the soil up to 4 years. Scientists fear that it could infect a crop before it even emerges above ground.

Currently, potato farmers have to spray their crops up to 12 times a year. But Mullins and his colleagues hope to create a variety that will only need to be sprayed 4 times a year. The decreased use of fungicides would, in turn, mean less damage to the environment.

Mullins said farmers relying on normal potato crops would also be affected by new EU regulations aimed at reducing use of pesticides and fungicides. "If we were to reduce chemicals by up to 40 percent on our potato crop, that would challenge potato growers," he said. "We [think] GM is worth investigating from that point of view."

Teagasc is investigating the environmental impact of a number of GM crops and whether they could provide an economic benefit to farmers via reduced chemical costs. Newer varieties are more disease resistant.

[Byline: Lynne Kelleher]

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

[Late blight of potato and tomato is caused by the fungus-like organism _Phytophthora infestans_ and can cause 100 percent crop loss. It is spread by contaminated plant and other material, wind and water. Solanaceous weeds and volunteer crop plants can serve as pathogen reservoirs. Fungi and bacteria often invade blight-infected
potato tubers resulting in total tuber breakdown. Under favorable conditions, epidemics in tomatoes may be even more rapid than in potatoes.

Disease management includes preventative fungicide treatment of planting material (potato seed tubers, tomato transplants) and additional fungicide applications to the crop. While commercial crop cultivars vary in susceptibility to late blight, development of resistant cultivars is being counteracted by the adaptability of the pathogen, with new strains evolving all the time. For more information on late blight, see ProMED-mail post no. 20080219.0664
and links below.

Maps
USA:
<http://www.mapsofworld.com/usa/usa-road-map-enlarge-view.html>  and
<http://healthmap.org/promed/en?g=5481136&v=34.5,-106.001,5>
US states:
<http://www.census.gov/geo/www/us_regdiv.pdf>
Ireland:
<http://www.fishing-ireland.de/karte.html>  and
<http://healthmap.org/promed?v=53.2,-8.2,5>

Pictures
Late blight on potato:
<http://www.sciencedaily.com/images/2007/01/070102132649.jpg>  and
<http://www-biol.paisley.ac.uk/bioref/Chromista/potato_blight.jpg>
Late blight on tomato:
<http://www.omafra.gov.on.ca/english/crops/hort/news/hortmatt/2006/23hrt06a3f1.jpg>
Tomato field destroyed by late blight:
<http://www.apsnet.org/online/feature/BioSecurity/Images/lateblightbolkan.jpg>

Links
Late blight fact sheets:
<http://ohioline.osu.edu/hyg-fact/3000/3102.html>  and
<http://vegetablemdonline.ppath.cornell.edu/factsheets/Potato_LateBlt.htm>
Disease history and background:
<http://www.apsnet.org/online/feature/lateblit/>  and
<http://www.olympusmicro.com/micd/galleries/brightfield/potatoblight.html>
Late blight information and resources via:
<http://www.potato.org.uk/department/knowledge_transfer/fight_against_blight/advice_blight.html>
_P. infestans_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=232148>
Global Initiative on Late Blight:
<http://gilb.cip.cgiar.org/>
Teagasc:
<http://www.teagasc.ie/>
- Mod.DHA]

[see also in the archive:
2008
----
Late blight, potato - India, Canada alert 20080815.2534
Late blight, potato - UK: (Scotland), alert 20080430.1482
Late blight, tomato, potato - USA: (FL) 20080219.0664
2007
----
Late blight, potato - UK: new strains 20071207.3939
Late blight, potato & vegetable fungal diseases - Europe 20070708.2174
Late blight, potato - India, UK 20070509.1491
2006
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Late blight, potato - USA (AK), Bangladesh 20060324.0911
Late blight, tomato - USA (FL) 20060208.0416
2005
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Potato late blight - USA (AK) 20050901.2580
Potato late blight - UK (England, Wales) 20050630.1846
2004
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Potato late blight, tomato - USA (multistate) 20040817.2279
Potato late blight - USA (Idaho) 20040729.2071
Potato late blight - Ireland: 1st report 2004 20040602.1499
2002
----
Potato late blight, potato - Canada (Newfoundland) 20020818.5091]
 

 

 

 

 

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