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[1] Date: 6 Feb 2009
Source: Horticulture Week [edited]
<http://www.hortweek.com/news/bulletin/GrowerBulletin/article/878514/?DCMP=EMC-GrowerBulletin>
[registration required]
High levels of _Potato virus Y_ (PVY) found in farm-saved seed
potatoes destined for the 2009 crop have prompted the National
Institute of Agricultural Botany (NIAB) to urge potato growers
to get seed testing under
way if they have not already done so. NIAB head plant
pathologist Jane Thomas said while virus levels overall are
lower than in some years, a quarter of samples received by NIAB
had been infected with PVY, with one in 10 tubers infected at
levels high enough to cause serious damage in some varieties.
"The levels are probably a reflection of how well growers were
able to get on with their aphicide programmes last season
[2008]," she said.
Virologist Adrian Fox of Central Science Laboratory [UK
Department for Environment, Food & Rural Affairs], which also
offers a virus-testing service, said not all potato varieties
are susceptible to the same viruses but recommends testing for
PVY and _Potato leaf roll virus_ as a minimum. "It's important
growers know the susceptibility of varieties to different
viruses. The safest thing to do is to test for all of them," he
said.
Thomas advised growers to take soil samples for nematode testing
when soil conditions allowed. "The incidence in samples we've
seen has shown a noticeable presence of free-living nematodes,
which is a worry," she said. "They cause damage by direct
feeding on roots." Other crops, particularly carrots, may also
be affected.
--
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ProMED-mail <promed@promedmail.org>
[2] Date: 30 Jan 2009
Source: Horticulture Week [edited]
<http://www.hortweek.com/resources/PestsAndDiseases/876426/NIAB-warns-growers-test-farm-saved-potato-seed-virus/>
[registration required]
Growers should ensure farm-saved seed [tubers] is tested for
virus to avoid costly disease problems, warned the National
Institute for Agricultural Botany (NIAB).
While _Potato leaf roll virus_ was largely absent this year
[2008/2009], a quarter of farm-saved seed potatoes had been
infected at some level with _Potato virus Y_, one of the most
serious viruses affecting crop yields and tuber quality, said a
NIAB representative. To date, one in 10 tuber samples analysed
by NIAB showed infection levels of 20 per cent.
NIAB is also advising growers to take soil samples for
free-living nematode tests, as samples have revealed high
populations of _Pratylenchus_. This could damage root crops,
leading to reduced growth, yellowing and lesions.
--
communicated by:
ProMED-mail <promed@promedmail.org>
[_Potato Virus Y_ (PVY; type member of genus _Potyvirus_) is one
of the most damaging potato viruses. Different strains of PVY
can cause a range of symptoms, from a mild mosaic to severe
foliar necrosis. The most virulent
strain, PVY-NTN, causes interveinal mosaic on leaves and
distinctive ringed necrotic areas on tubers. PVY can also affect
tomato, capsicum and some other related species. It is
transmitted by aphid vectors and can also be
spread by mechanical means, plant-to-plant contact, or with
infected planting material such as seed tubers.
_Potato leafroll virus_ (PLRV; genus _Polerovirus_) is another
serious pathogen of the crop and can be transmitted by aphids as
well as seed tubers. PLRV can also affect tomato and a number of
weeds, and different potato cultivars may show different levels
of susceptibility.
Around 40 viruses have been reported to affect potato, and since
the crop is vegetatively propagated, many of them may be
disseminated in tubers. If virus-infected seed tubers are used,
virus populations and numbers of
co-infecting species will build up with every crop cycle. This
invariably leads to severely reduced plant vigour and a dramatic
drop in yield. The important role that tubers play in virus and
viroid spread is recognised by the strict requirements for
certified seed potato production in many countries worldwide.
Disease management of potato viruses relies largely on clean
planting material, but reduction of available virus reservoirs
and vector numbers may also be useful.
Around 10 species of _Pratylenchus_ (root lesion nematodes) are
known to affect potato and other root crops. Pathogenic effects
vary with species. Some reduce yield only when present at very
high levels in soil, while other more virulent species can
reduce yields already at low soil population numbers. Usually,
nematode numbers build up in soils over several years until they
reach levels that can affect crops. Management for soil nematode
diseases mainly relies on exclusion and crop rotation with
non-host species.
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:
PVY symptoms on potato:
<http://www.inra.fr/hyp3/images/6034404.jpg>
(leaves),
<http://www.umext.maine.edu/images/PVY.jpg>
(leaves),
<http://www.inra.fr/hyp3/images/6034401.jpg>
(plant) and
<http://www.ascenion.de/fileadmin/ascenion/Technology_Offers/Agro_Technology/Plant_Virus_Resistance.jpg>
(tubers)
PVY symptoms on tomato leaf:
<http://www.avrdc.org/photos/tomato_diseases/PVY_01.jpg>
Potato virus symptoms, photo gallery:
<http://vegetablemdonline.ppath.cornell.edu/PhotoPages/Potatoes/Viruses/PotVirusPhotoList.htm>
PVY particles, electron micrograph:
<http://www.ppi-bg.org/i/sn5.jpg>
_Pratylenchus_ root lesion nematodes:
<http://www.umanitoba.ca/afs/graphics/fiw_tenuta_fig1.jpg>
Links:
Information on _Potato virus Y_:
<http://www.agric.wa.gov.au/content/PW/PH/DIS/FS00203.PDF>,
<http://www.inra.fr/hyp3/pathogene/6potviy.htm>
and
<http://www.oregon.gov/ODA/CID/PLANT_HEALTH/profilepvy.shtml>
Information on PVY and PLRV:
<http://www.umext.maine.edu/onlinepubs/htmpubs/2492.htm>
Virus and viroid diseases of potato, factsheet:
<http://vegetablemdonline.ppath.cornell.edu/factsheets/Virus_Potato.htm>
PVY taxonomy and description:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.057.0.01.001.htm>
PLRV taxonomy and description:
<http://www.ncbi.nlm.nih.gov/ICTVdb/ICTVdB/00.039.0.02.001.htm>
Taxonomy of all other potato viruses via:
<http://www.ncbi.nlm.nih.gov/ICTVdb/Ictv/index.htm>
_Pratylenchus_ taxonomy, species list and information via:
<http://plpnemweb.ucdavis.edu/nemaplex/taxadata/g105.htm>
List of potato viruses and nematodes:
<http://www.apsnet.org/online/common/names/potato.asp>
NIAB:
<http://www.niab.com/>
Central Science Laboratory:
<http://www.csl.gov.uk/>
- Mod.DHA]
[see also
in the
archive:
2008
---
Unspecified virus, potato - Uganda (KB) 20080317.1038
Potato diseases - India: (West Bengal) 20080206.0477
Viruses, potato - UK: (Scotland) 20080130.0383
2007
---
Potato spindle tuber viroid, potato - Russia: novel strains
20070423.1323
2002
---
Potato virus Y, necrotic strain - USA (north west) 20021001.5434
1997
---
Potato viruses - Saudi Arabia 19970414.0796]
