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POTATO DISEASES - INDIA: (WEST BENGAL)
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A ProMED-mail post
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International Society for Infectious Diseases
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Date: Fri 1 Feb 2008
Source: The Statesman [edited]
<http://www.thestatesman.net/page.arcview.php?clid=23&id=215566&usrsess=1>
Drizzling and prolonged foggy weather caused extensive damage to
thousands of hectares of potato cultivation in Birbhum [district]
this year [2008]. The district expected 20 lakh [2 million] tonnes of
production but according to the district agricultural authority,
production would be reduced by a huge percentage due to the rough
weather right before harvesting. Adding to the problem, a bulk of the
produce has become victim to the late blight, leafroll virus, and
bacterial wilt.
Birbhum cultivated more than 20 000 hectares (49 421 acres) of potato
across 19 blocks, but this year [2008] the cultivation area has been
increased by 5000 hectares (12 355 acres). According to a senior
agricultural officer of Birbhum: "10 out of 19 blocks are worst hit
due to the calamity. Though the disease was curable to some extent,
the stored produce got badly damaged." He also said that [district]
officials have already visited several blocks recently to prepare a
final report on the damage. The potato farmers of the district
alleged that due to ignorance of such diseases they are incurring
huge loss every year. "Potato cultivations need proper treatment on
time to prevent damages from such diseases but due to lack of proper
guidance from the district agricultural department the farmers are
facing difficulties to deal with these diseases," alleged a farmer.
Mr Prasun Kanti Ghosh and Mr Joydev Fulmali research scholars of
Visva-Bharati's Agricultural department, who are doing research work
of potato in different fields said, "The farmers need to observe the
symptoms of the diseased plants regularly and then consult with the
agricultural officers for proper treatment of the diseases."
[Byline: Sabyasachi Roy]
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ProMED-mail
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[Late blight
------------
Potato late blight (PLB) is caused by the fungus _Phytophthora
infestans_, which can also infect other solanaceous crops such as
tomato or eggplant. It is one of the most important potato diseases
worldwide affecting both leaves and tubers. It is favoured by cool,
moist conditions. The fungus is spread by plant material (including
seed tubers), wind and water. Solanaceous weeds can serve as pathogen
reservoirs. Other fungi and bacteria often invade blight-infected
tubers resulting in total tuber breakdown. Late blight is a concern
in many countries because new and even more virulent strains are
emerging, some of which can destroy a potato plant within hours.
Disease management includes preventative fungicide treatments of seed
tubers as well as fungicide sprays of crops. In India, infected seed
potatoes are typically the main source of disease inoculum, and
losses of up to 75 percent have been reported previously in some
areas. Several PLB resistant varieties are being deployed around the
country and a forecasting model has been developed to determine the
timing of fungicide applications.
Leafroll
--------
_Potato leafroll virus_ (PLRV; genus _Polerovirus_) is a destructive
pathogen causing reduction in yields and poor quality tubers.
Symptoms include curling and chlorosis of leaves and stunting of
plants. In storage, infected tubers often develop "net necrosis"
(brown strands beneath the skin), depending on potato cultivar and
storage conditions. PLRV can also affect tomato and a number of
solanaceous and cruciferous weeds. The virus is transmitted by
aphids, with _Myzus persicae_ being the most efficient vector, as
well as seed tubers. Chronically infected plants growing from
infected tubers are a main source of PLRV in commercial potato
fields. Disease management includes clean planting material, removal
of pathogen and vector reservoirs (volunteer potatoes, weeds),
phytosanitary measures, and vector control. Potato cultivars with
different levels of susceptibility to PLRV, including some which do
not develop net necrosis, are available.
Bacterial wilt
--------------
This disease is also called brown rot and is caused by _Ralstonia
solanacearum_ race 3, which is widely distributed in warm temperate
areas. The effect on food- and seed-potato industries can be
substantial, and tomato crops are also susceptible. Symptoms include
wilting, stem discolouration, brown internal staining of tubers, and
plants may die. Symptom expression is favoured by temperatures above
15 deg C (59 deg F). The bacteria may also latently infect tubers
without causing symptoms and can survive in seed tubers during
storage. The pathogen is spread by mechanical means (including
insects), contaminated equipment, infected plant material (including
seed tubers), and water. Solanaceous and other weeds and volunteer
potatoes may serve as pathogen reservoirs. Yield losses are mostly
caused by tuber rotting and, in many warmer areas of the world, brown
rot is one of the main limiting factors in potato production.
Although the weather patterns have obviously been very unfavourable
for the crop, there appear to be some problems that need to be
addressed urgently in the region. These seem to include the use of
infected seed tubers, lack of efficient phytosanitary measures, and
suboptimal control of pathogen reservoirs. The call for more training
and support for the local farmers also appears to be justified.
Maps
India:
<http://www.globalsecurity.org/military/world/india/images/IndiaMap_tourism.gif>
and
<http://healthmap.org/promed?v=22.9,79.6,5>
West Bengal districts:
<http://www.mapsofindia.com/maps/westbengal/westbengal-district.htm>
Assorted maps of Birbhum via:
<http://birbhum.gov.in/MAPS/Map_index.html>
Worldwide distribution of _R. solanacearum_ race 3 (September 2006):
<http://www.eppo.org/QUARANTINE/bacteria/Ralstonia_solanacearum_race3/PSDMS3_map.htm>
Pictures
PLB symptoms:
<http://www.sciencedaily.com/images/2007/01/070102132649.jpg> (tuber) and
<http://www-biol.paisley.ac.uk/bioref/Chromista/potato_blight.jpg> (leaf)
PLRV symptoms:
<http://www.gov.mb.ca/agriculture/crops/potatoes/images/bda04s07-p27.jpg>
(tuber) and
<http://www.gov.mb.ca/agriculture/crops/potatoes/images/bda04s07-p26.jpg>
(leaf)
Brown rot symptoms:
<http://www.eppo.org/QUARANTINE/bacteria/Ralstonia_solanacearum/PSDMSO_images.htm>
and
<http://www.redepapa.org/murcha.jpg>
Links
Late blight information, history and background:
<http://www.apsnet.org/online/feature/lateblit/>, and
<http://www.olympusmicro.com/micd/galleries/brightfield/potatoblight.html>
Management of potato diseases including early and late blights:
<http://archives.eppo.org/EPPOStandards/PP2_GPP/pp2-02-e.doc>
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>
Information on PLRV:
<http://www.wsu.edu/~potatoes/leafroll.htm> and
<http://www.uidaho.edu/ag/plantdisease/potnet1.htm>
PLRV taxonomy:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.039.0.02.001.htm>
Brown rot disease information:
<http://www.defra.gov.uk/planth/brownrot.htm>
Description and taxonomy of _R. solanacearum_:
<http://expasy.org/sprot/hamap/RALSO.html> and
<http://www.ebi.ac.uk/2can/genomes/bacteria/Ralstonia_solanacearum.html>
History and description of races:
<http://www.eppo.org/QUARANTINE/bacteria/Ralstonia_solanacearum/pm7-21(1)%20PSDMSO%20web.pdf>
List of potato diseases and pathogens:
<http://www.apsnet.org/online/common/names/potato.asp>. - Mod.DHA]
[see also:
Viruses, potato - UK: (Scotland) 20080130.0383
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
Brown rot, potato - Ireland: 1st report 20071022.3438
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
2005
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Bacterial wilt, potato - Egypt 20050519.1378
2004
----
Clavibacter and Ralstonia, potato - United Kingdom 20040831.2425
Ralstonia solanacearum, potato - Slovakia: 1st report 20040626.1702
Ralstonia solanacearum, survey - United Kingdom 20040110.0109
2003
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Clavibacter sp., Ralstonia sp., potato - Germany 20030814.2020
Late blight, potato - Papua New Guinea 20030306.0554
2002
----
Clavibacter and Ralstonia spp., potato - Germany 20021016.5561
Potato late blight, potato - Canada (Newfoundland) 20020818.5091
2001
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Phytophthora infestans, potato late blight - Russia 20010620.1177
Regulated plant pests, detection, Feb 2001: EPPO 20010615.1152
2000
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Potato late blight, global research efforts 20001031.1903
Ralstonia solanacearum, potatoes - Hungary 20001010.1733
Potato late blight: global initiative 20000516.0765
1999
----
Ralstonia solanacearum, potatoes - Syria? (02) 19991210.2143
Ralstonia potato wilt, prevention - France 19990820.1441
Ralstonia solanacearum, potatoes - Syria? 19990703.1117
Potato & tomato diseases - Europe 19990524.0863
1997
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Potato viruses - Saudi Arabia 19970414.0796
1996
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Potato late blight: global threat 19960617.1123]
...................................dha/mj/dk
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