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: April 29, 2008
Source: The Scotsman [edited]
<http://business.scotsman.com/fooddrinkagriculture/Warning-over-virulent-strain-of.4028912.jp>
Warning over virulent strain of blight
Farmers have learned how to deal with potato blight in the 160
years since Ireland's great famine, and the advent of modern
agro-chemicals has done much to cut crop losses. However, the
disease, which is caused by the fungus _Phytophthora infestans_,
has mutated over the years and the current strain is especially
virulent.
Rob Clayton of the Potato Council, the organisation funded by
growers, said: "We're now dealing with a different type of
blight. We are expecting an early start to the season and
control measures may have to remain tight. Growers should be
deciding their control strategy around how this type behaves in
the field. This year [2008], more than ever, best practice
really does mean best practice."
Blight is the number-one potato disease, and while Scottish
crops tend to be less susceptible because of a generally cooler
and less humid climate than in England, losses can still be
considerable.
Growers throughout the UK are estimated to spend at least GBP 20
million (about USD 39.6 million) each year on blight control.
Clayton recommends constant vigilance of all potato crops from
emergence early next month [May 2008] and advises growers to
discuss spraying programmes with an agronomist. Growers might be
well advised to vary the mix of chemicals throughout the season.
The Potato Council runs a combined "Fight Against Blight" and
"Blightwatch"
service to provide early warnings of disease outbreaks. Clayton
said:
"It is vital that growers make good use of these services. This
is now an integral part of Britain's defence in the battle
against blight, and the 350 'blight scouts' play a crucial role
in supplying samples and identifying actual outbreaks."
[Byline: Dan Buglass]
--
Communicated by:
ProMED-mail
<promed@promedmail.org>
[Potato late blight (PLB) is caused by the fungus _Phytophthora
infestans_, which can also infect other solanaceous crops such
as tomato or eggplant. The fungus affects leaves as well as
tubers and can cause 100 percent crop loss. It is spread by
plant material (including seed tubers), wind and water, and
solanaceous weeds can serve as pathogen reservoirs. Other fungi
and bacteria often invade blight-infected tubers resulting in
total tuber breakdown. Disease management includes preventative
fungicide treatment of seed tubers and additional fungicide
applications to the crop. Some PLB resistant potato varieties
are available.
Worldwide, considerable variation in aggressiveness between
different isolates of _P. infestans_ has been observed. A severe
form of PLB was responsible for the Irish potato famine in the
late 1840s, but PLB is still the most devastating disease
threatening potato crops worldwide today. According to the Food
and Agriculture Organisation of the United Nations (FAO), at
present around 20 percent of the worldwide potato crop is
destroyed by PLB each year. The pathogen is considered an
increasing problem in many areas because new and even more
virulent strains continue to emerge. Some of these can destroy a
potato plant in a matter of hours and a complete crop within
days.
When both of the mating types, A1 and A2, are present,
reproduction occurs sexually as well as asexually, leading to
strains with higher fungicide resistance and increased yield
losses. A1 was the first to spread worldwide. A2 began to spread
later, and in Western Europe a dramatic increase in the
frequency of A2 is being recorded recently.
The report above refers to the threat posed by new more
aggressive blight strains that are currently emerging in the UK
(see ProMED-mail post no. 20071207.3939).
Maps of the UK:
<http://www.lib.utexas.edu/maps/europe/united_kingdom.gif>
and <http://healthmap.org/promed?v=54.5,-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>
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>
UK populations of late blight and map of A2 distribution:
<http://www.scri.ac.uk/research/pp/pestanddisease/blightepidemiologyandpopulationbiology>
British Potato Council:
<http://www.potato.org.uk>
Global Initiative on Late Blight:
<http://gilb.cip.cgiar.org/>.
- Mod.DHA]
[see also in
the
archive:
Late blight, tomato, potato - USA: (FL) 20080219.0664 Potato
diseases - India: (West Bengal) 20080206.0477 Late blight,
potato - Papua New Guinea: recovery 20080121.0256 Fungal
diseases, potato - Bangladesh 20080107.0091
2007
----
Late blight, potato - India (02): (Punjab, W Bengal)
20071221.4099 Late blight, potato - UK: new strains
20071207.3939 Late blight, potato - India: (Punjab), alert
20071116.3715 Fungal diseases, vegetable crops - Canada:
cucumber, potato 20070730.2442 Late blight, potato & vegetable
fungal diseases - Europe 20070708.2174 Late blight, potato -
India, UK 20070509.1491
2006
----
Late blight, potato - India (Kashmir) 20060424.1200 Late blight,
potato - USA (AK), Bangladesh 20060324.0911
2003
----
Late blight, potato - Papua New Guinea 20030306.0554
2002
----
Potato late blight, potato - Canada (Newfoundland) 20020818.5091
2001
----
Phytophthora infestans, potato late blight - Russia
20010620.1177 2000
----
Potato late blight, global research efforts 20001031.1903 Potato
late blight: global initiative 20000516.0765
1996
----
Potato late blight: global threat 19960617.1123]
