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Global Invasive Species Team listserve digest #036
Tue, 13 Jul 1999 17:47:04 -0700 (PDT)
--CONTENTS--
1. Horses and weeds
2. Japanese honeysuckle dying?
3. Keeping knapweed hazards in perspective
4. On unintended Arsenal damage
5. Biocontrol of Phragmites australis
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1. Horses and weeds
From: Malcolm Hodges (mhodges(at)tnc.org)
A landowner contributing land wants to retain a right to install a horse
trail. We are concerned that field weeds will be transferred via horse
manure to this natural Georgia flatwoods. Please share any information on
the horse/exotic plant connection via the listserve.
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2. Japanese honeysuckle dying?
From: Malcolm Hodges (mhodges(at)tnc.org)
Does anyone have information on what appears to be some sort of fungal
infection on Japanese honeysuckle? In many areas of Georgia, leaves on
plants are yellowing and puckering, and a white dust appears on the plant;
many plants appear weakened, and some are dying. Other plants remain
quite vigorous, however, especially in high light situations.
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3. Keeping knapweed hazards in perspective
From: Eric Lane (Eric.Lane(at)ag.state.co.us)
I hesitate to perpetuate the dialogue on pulling spotted knapweed any
further than necessary but many individuals who pull spotted knapweed, as
well as diffuse knapweed, can expect to experience the bitter taste
(transferred from hand to mouth or water bottle). It's nothing more than
what would happen if you pulled mint plants all day and then wondered
about that curious mint flavor you might later savor (shoulda been a
poet). For folks with more sensitive skin, like yours truly, slight rashes
are predictable if you have exposed skin.
As for other symptoms such as nausea or headaches: In sunny Colorado, I am
tempted to attribute these symptoms to the exposure to sun and dehydration
that many volunteers are subjected to from a few hours of pulling in the
heat.
Recommendations: When pulling noxious weeds, make sure that you, or your
volunteers, wear gloves (you never know when you'll meet a thistle you
don't like), wear headwear, and stay hydrated. I typically wear a
light-weight, long-sleeve shirt and pants to avoid to much contact with
the plant life and exposure to sun. If you're pulling knapweeds, you can
expect the occasional bitter taste. I find that you can reliably remove
this foul taste and keep volunteers happy by administering small doses of
M&Ms (any flavor will do just fine).
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4. On unintended Arsenal damage
From: Neil Gifford (apbpc(at)aol.com)
In 1998 a local power company used Arsenal in an experimental foliar
treatment (from backpack sprayers) of thick 10 - 15 foot tall scrub oak
and black locust on one of their PROW's through the New York Albany Pine
Bush Preserve. While the qualitative report is not yet available, our
visual inspection of the area showed that everything in the treated area,
except some forbs (wild blue lupine) had been killed. This included all
other ground cover. We have not, however, seen any evidence of
"collateral" damage outside the treated area (yet?).
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5. Biocontrol of Phragmites australis
From: Judy Preston (jpreston(at)tnc.org)
At an early May meeting in Amherst, Massachusetts, the US Fish and
Wildlife Service pulled together participants from a number of
organizations in the Northeast to summarize the current state of
investigations and future needs for a biological control program for the
common reed, Phragmites australis.
There are two native insects that can impact Phragmites: Poanes viator, a
skipper (Lepidoptera: Hesperiidae); formerly rare (it fed on wild rice)
and is now common and feeding on Phragmites, and Dicramoctetes saccharella
(Lepidoptera: Elachistidae), the Leaf Blotch miner. Neither one appears
to be devastating Phragmites, although it is unknown at what point they
might become more effective.
There are seven non-native but probably "naturalized" (considered
accidental introductions) insects, two of which hold promise as biocontrol
agents. Liparis similis, a Shoot Fly (Diptera: Chloropidae) is known from
CT, NY and RI (where some sites have been found with >50% infestation).
Larvae burrow into Phragmites shoots, preventing flowering and resulting
in two vegetative "flags" (4-8 inches long) at the stalk tip. Rhizedra
lutosa (Lepidoptera: Noctuidae), described from New Jersey, but also found
in CT, MA, RI, and MD, damages the rhizome. Its indication is stunted
plant growth that is entirely yellow.
Primary researchers involved in these insect investigations are from the
University of Rhode Island (Richard Casagrande et al) and Cornell (Bernd
Blossey and Mark Schwarzlaender). Literature (including a one page list
of native and introduced biocontrol species) and minutes are available
from this meeting (email Judy Preston, CTFO, jpreston(at)tnc.org).
---Note from John Randall:
As natural area managers we should carefully consider if we could support
the intentional introduction of non-native insects to control Phragmites
some time in the next 3-10 years. Researchers have already found at least
two insect species in Europe with potential as Phragmites biocontrol
agents and will likely begin testing to see if they feed on other North
American native plants. Phragmites is a severe problem in many natural
areas in the eastern part of the US and southern Canada and is
extraordinarily difficult to control. However, Phragmites australis is
native to North America and is not a problem in most of the west, nor
along much of the Gulf coast. There is a hypothesis that a non-native
'biotype' of Phragmites was introduced and that this is the invasive
'type' now plaguing so many of our wetlands. Researchers from the
biocontrol program are investigating genetic variations in North American
and European populations to look for evidence to support (or refute) this.
Even if a non-native 'type' of Phragmites is found it is highly unlikely
that a biocontrol agent could be found that will attack only that 'type'
while leaving the native (presumably non-invasive) 'types' alone. The
researchers involved should be commended for continuing to conduct such
vitally important and useful background work. However, at this time, I
personally cannot support intentional releases of species not already in
North America against Phragmites.