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BACTERIAL WILT, POTATO - EGYPT
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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: 19 May 2005
From: ProMED-mail<promed@promedmail.org>
Source: Cairo Magazine, 12 May 2005 [edited]
<http://www.cairomagazine.com/?module=displaystory&story_id=910&format=html>
Tuber troubles, record number of potatoes, but who will eat them?
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Egyptian potato producers and exporters face a new ban on potato shipments
from the European Union [EU] following a sudden outbreak of brown rot (BR)
in mid-February 2005. Greek officials notified the Egyptian Ministry of
Agriculture that several cases of BR, a bacterial disease that attacks the
vascular bundles in potatoes and rots out the inside of the tuber, had been
found. Greece banned all potato imports from Egypt, with most members of
the EU following suit.
According to Safwat Al Jadad, director of the Brown Rot Eradication Project
in Cairo, a division of the Ministry, only a few cases (<1 percent) of
diseased potatoes were discovered in shipments entering Greece. He was
shocked to learn that the EU has already imposed a ban again on our exports.
The office of the European Commission (EC) in Egypt defended the EU ban on
the grounds that several countries, including the U.K., Italy, Greece and
the Netherlands, reported being sent infected shipments.
This is the 2nd time that Egyptian exports have faced a ban from European
countries. In April 1999, the EU introduced a similar ban on Egyptian
potatoes after the number of infested consignments rose. Egypt applied the
"pest-free area" system, in which soil is considered diseased unless proven
free of BR. By 2000, after months of negotiations, the EU agreed to again
import potatoes planted in those areas as long as the number of intercepted
cases is less than 5.
According to Hamdi Al Tahan, chairman of the General Committee for Potato
Exporters at the Federation of Chambers of Commerce, no changes have been
made in potato production. All the potatoes that are exported are free from
BR, but the EU began to worry after Egyptian potato exports increased
tremendously in 2004. According to the latest statistics from the
Agriculture Ministry, the number of potato exports has risen from 250 000
tons in 2004 to 350 000 tons in 2005. The EU had received between 200 000
to 250 000 tons as of the start of the ban.
Exports have been increasing dramatically over the past few years, jumping
from $5.5 million worth in 2002 to $20 million in 2004.
Al Tahan commented that the crop was to be the best year for Egyptian
exports in decades, but the ban turned everything upside down. Now, a ton
of potatoes is sold for LE 190-200 instead of LE 1200.
Last week, several members of parliament pressured the Agricultural
Ministry asking for immediate action by the government. Meanwhile, potato
producers have to determine how to distribute the EU's portion of the 2.5
million tons planted this year. According to Atta Muhammad, a potato
producer in Menoufiya, this huge amount cannot be consumed domestically.
[Byline: Summer Said]
--
ProMED-mail
<promed@promedmail.org>
[The bacterium causing bacterial wilt (BW) is _Ralstonia solanacearum_
(Rs). It is found in tropical to temperate regions worldwide, as 25-30 deg
C is the optimum temperature for the strains. Rs can survive for several
years in the soil and also remain alive on host plants belonging to the
Nightshade family (tomato, nightshade, capsicum, aubergine, tobacco, etc.)
as well as other plants. It is spread by irrigation water or by infected
seed potatoes.
There are 3 races of Rs on the basis of pathogenicity. Within the species
38 RFLP groups have been distinguished, and they form 2 genetically
distinct major divisions with origins in Australasia and the Americas. The
host range, which includes over 200 plant species, is one of the widest of
all the phytopathogenic bacteria. Species infected by Rs include the
_Solanaceae_, but more than 50 other plant families also contain
susceptible species. Worldwide, the most important are: tomatoes, Musa
spp., tobacco, and potatoes. Many weeds are also hosts of the pathogen and
therefore increase the potential of Rs to build up inoculum.
Different pathogenic races within the species may show very limited host
ranges. Race 1 affects tobacco, tomatoes, potatoes, aubergines, diploid
bananas, and many other (Solanaceous) crops and weeds, and has a high
growth temperature optimum (35-37 deg C). Race 2 affects triploid bananas
and _Heliconia_ spp., and has a high temperature optimum (35-37 deg C).
Race 3 biovar 2 has a lower temperature optimum (27 deg C) and affects
mainly potatoes and tomatoes. A considerable number of additional
symptomless weed hosts have been reported, which may enable race 3 biovar 2
to survive in latent form, or in their rhizosphere. Several weed species
commonly inhabit edges of waterways, thus providing an inoculum source.
There are also reports of natural occurrence of race 3 biovar 2 in
_Pelargonium hortorum_. Within the EPPO-region, race 3 biovar 2 (equivalent
to biovar 2), is present and has potential for spread.
Rs is a contentious topic in agricultural trade negotiations in the EU and
is subject to strict quarantine and eradication regulations in the United
States. No economically feasible controls exist. Avoid planting on land
with a previous history of BW. Instead, grasses, legumes, and cucurbits
should be planted to reduce inoculum of Rs. - Mod.DH
Links:
<http://www.defra.gov.uk/planth/brownrot.htm>
<http://www.plantdepommedeterre.org/eng/disease/bactp.htm>
<http://ibws.nexenservices.com/from_july_%2001.htm>]
[see also:
2004
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Clavibacter and Ralstonia, potato - United Kingdom 20040831.2425
2003
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Clavibacter sp., Ralstonia sp., potato - Germany 20030814.2020
Clavibacter & ralstonia species, potato - Estonia 20011124.2882
2002
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Clavibacter and Ralstonia spp., potato - Germany 20021016.5561
Bacterial wilt, ring rot, potato - Estonia 20020723.4841
Bacterial wilt, potato - Canada (PEI) 20021215.6074
2001
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Bacterial wilt, potato - Slovenia 20010925.2336
2000
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Clavibacter & Ralstonia in water: chemical control 20000521.0804
1999
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Bacterial wilt, potato - Egypt: EU import ban 19990722.1236]
..........................dh/pg/mpp
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