[APWG] Fwd: rose rosette disease on wild roses (fwd)

[Olivia Kwong]

---------- Forwarded message ----------
Date: Mon, 2 Jan 2006 19:06:58 -0500
From: Sara Tangren <satangren at chesapeakenatives.org>
Subject: Fwd: rose rosette disease on wild roses

> Dear Friends,
>      The pasture roses at Chesapeake Natives' wildflower farm in
> Maryland appear to have this disease, called rose rosette disease.
> Alisa DeGeorge, who works at the Plant Pathology Lab of the
> University of Maryland was kind enough to send these articles on
> rose rosette disease.  According to the articles below the disease
> is evidently imported.  The good news is that multiflora rose is
> susceptible, the bad news is that multiflora roses are everywhere
> and acting as a reservoir for the disease.  More bad news is that
> the disease is consistently fatal to roses.  The two articles below
> briefly mention that the disease has been observed in wild rose
> populations.  Are we really in danger of losing all the wild roses
> in North America?
>      We will continue to take care of the wild roses at the
> wildflower farm.  Not all the roses were expressing symptoms last
> summer.  Either some of the roses have yet to be infected, or we
> may have some resistant individuals.
>      Is anyone out there studying and documenting the rose rosette
> situation as it pertains to wild roses?  Does anyone have field
> observations they can share?
>
> Sara Tangren, Ph.D., President
> Chesapeake Natives is a nonprofit dedicated to helping you with
> your  native plant needs.
> www.ChesapeakeNatives.org
> Mailing Address Only: 326 Boyd Ave. #2, Takoma Park, MD 20912
> Phone 301 580 6237
> Fax 301 270 4534
>
>
> Begin forwarded message:
>
>> From: Sara Tangren <satangren at chesapeakenatives.com>
>> Date: July 28, 2005 9:45:00 PM EDT
>> To: Sara Tangren <SATangren at ChesapeakeNatives.com>
>> Subject: OPEN ONLINE
>>
>>
>>
>> Begin forwarded message:
>>
>>> From: "Alisa DeGeorge" <alisad at comcast.net>
>>> Date: July 24, 2005 7:10:45 PM EDT
>>> To: "Sara Tangren" <satangren at chesapeakenatives.com>
>>> Subject: Rose Rosette - 2 good reference websites
>>>
>>> Here is some info I found on Rose Rosette ... it does refer to
>>> the History as being tied to the multiflora rose brought over
>>> from Japan.  Since the virus seems to spread by any mechanical
>>> means (they mention grafting) - the mite may have already been
>>> here and is just one of the possible vectors.  They don't mention
>>> if the mite was imported also.
>>>
>>> Virginia Coop Extenstion Service
>>> http://www.ext.vt.edu/pubs/plantdiseasefs/450-620/450-620.html
>>>
>>> History of Rose Rosette Disease
>>>
>>> Symptoms that were undoubtedly due to rose rosette disease were
>>> described in the United States as early as 1941. Spread of the
>>> disease in the United States was intimately tied to the history
>>> of the multiflora rose, an exotic plant that was introduced from
>>> Japan in 1866 as a rootstock for ornamental roses. During the
>>> 1930's through 1960's, planting multiflora rose was recommended
>>> for erosion control, as a bird sanctuary and food source, as a
>>> living fence for cattle, for strip mine reclamation, and as a
>>> crash barrier on highways. This recommendation ultimately
>>> backfired. Multiflora rose can produce a million or more seeds
>>> per plant and can propagate itself vegetatively as well. It
>>> quickly spread and is now declared a noxious weed in several states.
>>> Multiflora rose is highly susceptible to rose rosette disease, so
>>> much so that the disease was initially considered a potential
>>> biological control for multiflora rose. Even now, some people
>>> suggest introducing infected plants into areas with multiflora
>>> rose to control this weed. Most rose growers, however, are very
>>> wary of this recommendation because rose rosette disease can
>>> spread quickly from multiflora rose to cultivated roses.
>>>
>>> This other info is from Texas A&M Univerisity and mentions some
>>> treatment possibilities ... they don't feel like the hort oil is
>>> as effective. There is also a good photo of what the mite looks
>>> like on this site below.
>>>
>>> http://froebuck.home.texas.net/newpage2.htm
>>>
>>> These mites can only crawl and cannot fly, but they can "balloon"
>>> on the wind and travel great distances.  They are commonly found
>>> in air samples collected for spore and pollen counts.  According
>>> to Dr. Philley, the numbers of mites in such samples start out
>>> very low in the spring, begin to increase by June, peak in
>>> September, and then drop to zero after that.  This population
>>> count conforms to those made in other parts of the country.
>>>
>>> Prevention is always the best cure, and this means killing the
>>> mite, along with its eggs, before it can do any damage.  But
>>> miticides and other measures commonly used for treating spider
>>> mite infestations aren’t effective because this is a different
>>> type of mite.
>>>
>>> So far, the only chemical weapon that has proved to be effective
>>> is Cygon® (dimethoate), a systemic insecticide and miticide.  Dr.
>>> Philley says it might do the trick if sprayed twice, 7 days
>>> apart, and then monthly after that, starting early in the year as
>>> soon as the roses have leafed out.  (It will also control other
>>> sucking insects and mites, but it is generally ineffective
>>> against  tissue-chewing pests.)
>>>
>>> Unfortunately, according to a recent advisory released by Dr.
>>> Mike Merchant, Urban Entomologist with the Texas Cooperative
>>> Extension Service in Dallas, pesticide deletions currently
>>> proposed by the EPA will soon cause the dimethoates to become
>>> unavailable for use by home gardeners.
>>>
>>> Horticultural oil, neem oil, insecticidal soaps and the various
>>> seaweed products haven’t been effective against this mite, Dr,
>>> Philley says, because they’re not systemic.   Furthermore, it is
>>> difficult to get them down into the crevices where the mites live
>>> and breed.  However, horticultural oils may help prevent
>>> infestations if used to spray the bare canes just after the late
>>> winter pruning—and after all of the previous year’s leaflets,
>>> with their petioles, have been removed.