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: Sun 12 Sep 2010
Source: The Vancouver Sun, Edmonton Journal report [edited] <http://www.vancouversun.com/life/Fungus+wiping+tomato+plants+across+Alberta/
3514796/story.html>
Fungus wiping out tomato plants across Alberta
A fast-spreading fungus is wiping out tomato plants across Alberta.
The airborne disease called late blight of potato [and tomato] -- the same organism that led to the Irish Potato Famine -- is very rare in Alberta, said forensic plant pathologist Ieuan Evans. However, a "giant outbreak" of the disease is attacking tomato plants this [2010] season and causing hundreds of thousands of dollars in damage, he said.
"We've never had this strain in Alberta before -- it's a tomato strain and it's extremely virulent," he said. "On the prairies, the last time we had an outbreak of any consequence was 1993, but that was a potato strain."
Thunderstorms quickly spread the spores. The disease is also attacking tomatoes in Saskatchewan and Manitoba [see ProMED-mail post 20100712.2328].
Testing has shown some tomato seedlings sold in Edmonton were contaminated with the fungus. Those plants were likely imported from outdoor growing areas such as British Columbia. It's also possible the disease built up in potatoes before it spread to tomatoes. "It does not survive (winter) in Alberta on anything except stored potatoes. Any one showing any lesion or injury, cut the lesion out and eat the darn thing," said Evans.
[Byline: Andrea Sands]
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Communicated by:
ProMED-mail
<promed@promedmail.org>
[Late blight of tomato and potato is caused by the fungus-like organism _Phytophthora infestans_ and can cause 100 percent crop loss. The pathogen can affect leaves, stems, and fruit of tomato causing spots, lesions, and rotting, and in potato it affects leaves as well as tubers. The disease can spread rapidly within a crop and destroy it within a few days. It is spread by contaminated plant and other material, wind, and water. Under favourable conditions, epidemics in tomatoes may be even more rapid than in potatoes.
Disease management requires an integrated approach and may include phytosanitary measures, removal of pathogen reservoirs (solanaceous weeds, volunteer crop plants), limiting free moisture in the crop, preventative fungicide treatments of planting material (tomato transplants, potato seed tubers), fungicide sprays of crops, and crop rotation. 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 frequently.
It is not clear from the report above whether this is a new pathogen strain, or a previously know strain new to Alberta. Similar to what is suspected in Alberta, an outbreak of late blight on tomato in the USA in 2009 was also thought to have originated from infected tomato seedlings distributed widely (ProMED-mail post 20090519.1875).
Maps
Canada:
<http://www.lib.utexas.edu/maps/americas/canada_pol_1986.gif> and <http://healthmap.org/r/00bA>
Alberta:
<http://atlas.nrcan.gc.ca/site/english/maps/reference/provincesterritories/alberta/
referencemap_image_view>
Pictures
Late blight on tomato:
<http://www.omafra.gov.on.ca/english/crops/hort/news/hortmatt/2006/23hrt06a3f1.jpg>
and
<http://ipm.illinois.edu/ifvn/volume15/images/tomato_late_blight.jpg>
Late blight on potato:
<http://www.potatomuseum.com/images/exblightfieldwithinsert.jpg>,
<http://www.sciencedaily.com/images/2007/01/070102132649.jpg> (tuber), and <http://www.concordma.com/blog/Symptom_potato_late_blight.jpg> (leaf)
Links
Additional news stories:
<http://www.am770chqr.com/News/Local/Story.aspx?ID=1276900> and <http://www.freshplaza.com/news_detail.asp?id=68048>
Late blight fact sheets:
<http://ohioline.osu.edu/hyg-fact/3000/3102.html> and <http://vegetablemdonline.ppath.cornell.edu/factsheets/Potato_LateBlt.htm>
Late blight on tomato:
<http://www.omafra.gov.on.ca/IPM/english/tomatoes/diseases-and-disorders/late-blight.html>
Disease history and background:
<http://www.apsnet.org/edcenter/intropp/lessons/fungi/Oomycetes/Pages/
LateBlight.aspx>
Late blight information and resources via:
<http://www.potato.org.uk/department/knowledge_transfer/fight_against_blight/
advice_blight.html>,
<http://columbia.uwex.edu/ag/index.html>, and <http://www.euroblight.net/EuroBlight.asp>
_P. infestans_ taxonomy:
<http://www.indexfungorum.org/Names/NamesRecord.asp?RecordID=232148>
Global Initiative on Late Blight:
<http://gilb.cip.cgiar.org/>. - Mod.DHA]
[see also:
Late blight & mildew, vegetables - USA, Canada, update 20100712.2328 Late blight, tomato - USA: alert 20100519.1648
2009
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Late blight, tomato, potato - USA 20090629.2350 Late blight, potato & tomato: USA (FL), Ireland 20090109.0083
2008
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Late blight, potato - India, Canada alert 20080815.2534 Late blight type A2, tomato - Taiwan: 1st report 20080615.1891 Late blight, tomato, potato - USA: (FL) 20080219.0664
2007
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Fungal diseases, vegetable crops - Canada: cucumber, potato 20070730.2442 and additional items in the archives]
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