Hosta virus x found
Hosta virus x (HVX) was first identified in 1996
and has become more prevalent in the nursery trade
over the past few years. Several states have reported
the virus, and hosta societies are concerned about
the disease. In October, Massachusetts reported its
first case of HVX at a nursery in Middlesex County.
The varieties Sum & Substance, Striptease, and
Gold Edger tested positive when sent to Agdia for
ELISA testing. The nursery destroyed the infected
HVX is a potexvirus, and, currently, hostas are the
only known host. The most common symptoms of hosta
virus x are mottled or crinkled leaves. On plants
with gold leaves a green mottling, especially along
the vein, indicates viral infection. There are several
hosta viruses; so, virus testing is the only way to
determine which virus your plants have. Hosta varieties
can exhibit three different responses to HVX. (1)
Susceptible plants will show viral symptoms such as
mottling, leaf distortion, leaf desiccation, and poor
vigor when infected. (2) Tolerant plants can be infected
with the virus but show no symptoms. (3) Resistant
plants are not susceptible to infection by HVX. Dr.
Lockhart at the University of Minnesota has conducted
experiments to determine what category different cultivars
fall into. This work was written up in the article
“Hosta Virus X: A three year study” in
Hosta Journal in 2004. A few varieties are 100% infected
with HVX and were selected for their viral symptoms
such as interesting streaks, speckles or mottling
of the leaf. The varieties Breakdance, Leopard Frog,
Lunacy, and Eternal Father are reported as being infected
The best way to deal with HVX is to prevent it from
entering your nursery stock or garden and using good
sanitation. Buy quality, disease-free stock from a
reputable dealer. Keep new plants isolated to see
if they develop viral symptoms and/or have new lots
of hostas tested for HVX. Infected plants may go unrecognized
because symptoms can take a couple of weeks, months
or years to develop; and some tolerant plants may
remain asymptomatic while carrying the virus. HVX
is mechanically transmitted via transfer of infected
sap; so, good cultural practices prevent spread of
HVX. When cutting back or dividing hostas, clean tools
and hands before moving to the next plant or block
of plants. Deer browsing or a lawn mower blade can
also spread HVX; but the virus has not been shown
to spread via insects, nematodes, seeds, or pollen.
Once HVX infects a plant there is no cure. The only
way to get rid of the virus is destruction of the
plant. Hostas can be replanted in the same site, but
wait a few weeks to be sure no living hosta material
is present in the soil. HVX needs a living host and
does not persist in the soil without one. If you suspect
you have received plants that may be infected with
HVX, testing is available. Commercial flower growers
can send material to the UMass Plant Diagnostic Lab
for ELISA testing. The cost is $50 per sample. Visit
the UMass Floriculture website (http://www.umass.edu/umext/floriculture/grower_services/diagnostics.html)
or call the diagnostic lab (413-545-1045) for instructions
on sending samples. If you are a homeowner who has
a hosta plant you want tested, call Agdia at 1-800-622-4342.
Virus testing is expensive but may be warranted if
you have a particularly valuable variety in your collection.
Beckerman, Janna.2005. The X files: Hosta virus X.
University of Minnesota, Yard and Garden Line News,
Volume 7, Number 8. http://www.extension.umn.edu/yardandgarden/YGLN-June0105.html.
Accessed 6 February 2006.
Blanchette, B. and B. Lockhart. 2004. Hosta virus
X: A three-year study. The Hosta Journal. 35(3): 19-23.
Hosta Library website on Hosta Virus X- This site
has many photos.
Kirk, Willie.2005. About hosta virus X. Michigan
State University Landscape Alert, Vol.20, No.16. http://www.ipm.msu.edu/CAT05_land/L08-26-05.htm#3.
Accessed 6 February 2006.
The pest alert is from the Massachusetts Introduced
Pests Outreach Project, a collaborative project between
the Massachusetts Department of Agricultural Resources
and the UMass Extension Agriculture and Landscape
Program aimed at preventing the establishment of new
pathogens and pests in Massachusetts. Visit the project
for more information on hosta virus x and other emerging
pests or to subscribe
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