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
----
Late blight, potato - USA (AK), Bangladesh 20060324.0911
Late blight, tomato - USA (FL) 20060208.0416
2005
----
Potato late blight - USA (AK) 20050901.2580
Potato late blight - UK (England, Wales) 20050630.1846
2004
----
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]