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A ProMED-mail post
ProMED-mail is a program of the
International Society for Infectious Diseases
[1]
Date: Wed 21 Sep 2011
Source: Farms.com, Penn State University report [edited]
A new disease of soybeans
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Across the state [of Pennsylvania] this year [2011] I have noticed
some symptoms that couldn't quite be explained by our known soybean
diseases. We believe that these are the symptoms of a relatively new
virus called Soybean Vein Necrosis Virus (SVNV).
This was discovered in 2008 in Tennessee and Arkansas and has since
been confirmed in New York and most recently in Delaware and
Maryland.
We do not yet know whether this is a yield impacting disease. The
level of leaf damage I have seen suggests that at least in 2011 we
will not see yield reduction from this virus. In some cases, plants
that are infected by multiple viruses may have a significantly reduced
yield. We have seen some outbreaks of bean pod mottle virus in 2011,
and if the 2 occur in the same plant, it may overwhelm the plant's
resources.
I will be sending samples to the University of Arkansas to confirm the
virus in Pennsylvania.
[Byline: Alyssa Collins]
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[2]
Date: Fri 16 Sep 2011
Source: University of Delaware, Weekly Crop Update [edited]
Soybean vein necrosis virus in Delaware, Maryland, and Virginia
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Soybean vein necrosis virus was confirmed this week [week of 12 Sep
2011] by Yannis Tzanetakis, University of Arkansas. So the symptoms
that we have been seeing and sharing with concerned growers are due to
this new virus disease. Much work is being done in the Midwest to
identify the vectors and possible other hosts of the virus that may
harbor it and allow feeding vectors to move it to soybeans.
The question is: will it reduce yield or affect seed quality? So far I
have not seen enough leaf loss to imply yield effects, but we have
some time to go before maturity, so the jury is still out on the yield
effects here in the Mid-Atlantic.
The researchers have noted that multiple infections with other viruses
may increase yield loss potential. We have occasional outbreaks of
bean pod mottle virus and have seen soybean mosaic virus and peanut
stunt virus in the region, so the potential is here for multiple
infections. We do not have much information about the extent of other
virus diseases in soybeans.
Genetic resistance incorporated into good varieties will be the best
control strategy. That work is ongoing as well. It is too early for
recommendations but growers need to be aware of this disease and know
that work is being conducted to answer some of the pressing
questions.
[Byline: Bob Mulrooney]
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Communicated by:
ProMED-mail
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[3]
Date: Sat 10 Sep 2011
Source: Carroll County Times, Ag Today report [edited]
May be new virus on soybeans
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There might be a new virus on soybeans showing up in our region [of
Maryland]. It has not yet been confirmed, however, the symptoms are
consistent with pictures from around Maryland. So far the presumptive
diagnosis based on symptoms alone is of soybean vein necrosis virus.
This is a relatively new problem and has been detected and confirmed
in Arkansas, Illinois, Kansas, Kentucky, Missouri, and Tennessee. New
York has also indicated that it has samples with similar symptoms. If
these all turn out to be soybean vein necrosis virus, then this new
disease has spread rather rapidly.
It is not yet known how serious this disease can be with regard to
affecting yield. However, the pictures and descriptions from Arkansas
and Illinois indicate that significant leaf necrosis and possible
early defoliation can occur.
[Byline: Michael R Bell]
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Communicated by:
ProMED-mail
[A previously unknown virus was first identified in Tennessee in 2008
and in Illinois and Kentucky in 2009 (see ProMED-mal post
20100922.3430) as the cause of a new disease of soybeans. Symptoms
observed included vein clearing that becomes necrotic as leaves mature
leading to large necrotic regions on leaves and reduced plant vigour.
The name Soybean vein necrosis virus (SVNV) was suggested. Preliminary
classification based on protein comparisons coupled with phylogenetic
analyses has placed it in the genus _Tospovirus_ (family
_Bunyaviridae_), although it appears to have minimal similarity to
characterised members of the genus. Many tospoviruses are transmitted
by thrips, and these insects are also being investigated as possible
vectors of SVNV.
SVNV was found to affect a range of soybean cultivars and recent
surveys suggest that it may be widespread in the midwest and midsouth
of the US. No information is available yet on its presence in other
countries.
Disease management of crop viruses may include cultural techniques,
phytosanitary measures, vector control, and use of crop cultivars
resistant to the virus and/or the vectors. More information is needed
about the new virus before specific management strategies can be
designed.
Interactions between coinfecting viruses in plants are known to have
the potential to lead to severely increased effects on the host
(synergism; see link below). The mechanisms for this effect are as yet
unclear and it is therefore not possible to predict how SVNV may
interact in coinfections with the other soybean viruses mentioned
above.
Maps
USA:
Individual states via:
Pictures of SVNV symptoms:
progression)
Links
Information and updates on SVNV:
Molecular characterisation of SVNV:
Genus _Tospovirus_ taxonomy:
Taxonomy and information on all other viruses via:
Management of soybean viruses:
Implications of synergism on plant virus epidemiology:
- Mod.DHA]
[see also:
2010
----
New viruses, soybean - South Korea, USA 20100922.3430]
.................................................dha/mj/lm
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