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ProMED-mail post
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International Society for Infectious Diseases
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International Society for Infectious Diseases <http://www.isid.org>
Date: August 3, 2007
Source: North American Plant Protection Organisation,
Phytosanitary Alert [edited] <http://www.pestalert.org/viewNewsAlert.cfm?naid=46>
Nematologists have discovered a new cyst nematode in soil
samples taken from a field in northwestern Tennessee in 2006.
The report was confirmed in July 2007. The samples taken from
soil around stunted corn plants revealed juveniles and
lemon-shaped cysts. The nematode has physical characteristics
that differentiate it from _Heterodera_ species, including the
corn cyst nematode, _Heterodera zeae_. Genetic analyses
confirmed the cysts differed from _H. zeae_, but resulted in a
match with cyst specimens collected in Tennessee in 1978 from
goosegrass (_Eleusine indica_). So far, the nematode is reported
to reproduce well on a variety of hybrid corn cultivars, but
reproduced poorly on other monocots that were tested. No dicot
hosts have been reported.
If this nematode spreads to other crop production systems or
areas, it could make differentiation from other cyst nematodes
difficult, particularly if sampling and monitoring programs are
in place.
References:
1. Bernard, E., P.A. Donald, Z.A. Handoo, R. Heinz, and T.
Powers. 2007: Characterization of a New Species of Cyst Nematode
Parasitizing Corn. Journal of Nematology. 39: 74.
2. Tylka, G. 2007: New cyst nematode species on corn. Integrated
Crop Management. Iowa State University Extension. <http://www.ipm.iastate.edu/ipm/icm/2007/7-30/nematode.html>
--
Communicated by:
J. Allan Dodds
Former ProMED-mail plant disease moderator
<dodds@ucr.edu>
[Spread of this new cyst nematode could seriously hinder field
soil sampling as well as research on the biology and management
of soybean and maize cyst nematodes. Eggs of all cyst nematodes
look similar and cannot be distinguished by appearance.
Determining, for example, soybean cyst nematode (SCN) egg
population densities for management or research purposes would
be impossible using current techniques if other cyst nematodes
were present. A method that is specific for SCN eggs currently
is not available, and developing such a method
could take years.
Cyst nematodes known to affect maize are _Heterodera zeae_, _H.
avenae_ (cereal cyst nematode), _H. schachtii_ (sugarbeet cyst
nematode) and _Punctodera chalcoensis_. _H. zeae_ can cause
yield losses of up to 40 percent. It was 1st reported from India
and is now known to be present also in Pakistan, parts of Egypt
and the US. Symptoms are stunting, yellowing, and narrowing of
leaves. Stunting frequently occurs in irregular patches, and
development of tassels may be noticeably delayed. Other hosts
include millet, oat, rice, sorghum, sugar cane, and wheat, as
well as several grasses.
Another member of the genus is the soybean cyst nematode, _H.
glycines_.
Disease management for cyst nematodes includes crop rotation and
the use of partly resistant cultivars to keep populations low.
Elimination of cyst nematodes from infected fields is usually
not possible.
It is estimated that a very large number of nematode species
remains yet to be discovered.
Map of US states:
<http://www.census.gov/geo/www/us_regdiv.pdf>
Pictures
Females and cysts of new nematode:
<http://www.ipm.iastate.edu/ipm/icm/node/2568>
Females and cysts of _H. glycines_:
<http://www.ipm.iastate.edu/ipm/icm/node/2569>
Soybean field with _H. glycines_:
<http://www.ent.iastate.edu/imagegal/plantpath/soybean/scystnem/julyscnyellowing.html>
_H. zeae_ adult:
<http://www.mdinvasivesp.org/species/invertebrates/graphics/Corn_Cyst_Nematode_1.jpg>
Links
Disease description and information on _H. zeae_:
<http://nematode.unl.edu/Heteroderazeae.html>
and
<http://nematode.unl.edu/hzeae.htm>
_H. zeae_ taxonomy:
<http://plpnemweb.ucdavis.edu/nemaplex/Taxadata/G060S57.HTM>
Genus _Heterodera_, other species taxonomy via:
<http://plpnemweb.ucdavis.edu/nemaplex/Taxamnus/G060mnu.htm>
Genus _Punctodera_ taxonomy:
<http://plpnemweb.ucdavis.edu/nemaplex/Taxadata/G109.HTM>
News item, 'Farm Update: New Cyst Nematode Species On Corn':
<http://www.cattlenetwork.com/content.asp?contentid=149072>
Information on plant nematodes:
<http://plpnemweb.ucdavis.edu/nemaplex/index.htm>
List of nematodes affecting maize:
<http://plpnemweb.ucdavis.edu/nemaplex/hostlists/CornHostList.htm>
Methods for nematode identification:
<http://www.fao.org/docrep/v9978e/v9978e06.htm>
List of maize diseases and pathogens:
<http://www.apsnet.org/online/common/names/corn.asp>.
- Mod.DHA]
[see also in the
archive:
2006
----
Cyst nematodes, potato, soybean - USA (NY, IL): new strains
20060413.1092
2005
----
Soybean cyst nematodes - USA (MI) 20050916.2734
2004
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Soybean cyst nematode - USA (ND) 20041101.2950
2003
----
Soybean cyst nematode - USA (Arkansas) 20030709.1678
2002
----
Heterodera glycines, soybean - Europe: alert 20020802.4914] |
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