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Global Invasive Species Team listserve digest #074
Tue Dec 26 2000 - 16:48:36 PST

1. Weed job opening (Colorado)
2. Seeking case studies (Maryland)
3. Midwest invasive plant conference (Wisconsin)
4. Japanese hops (New York)
5. Recent weed articles (Nationwide)


1. Weed job opening (Colorado)
From: Eric Lane (Eric.Lane(at)ag.state.co.us)

-Eric Lane contacted the Wildland Invasive Species Team with news of a
job opening. Application deadline is January 5.

It is a two-year position funded by the Colorado Noxious Weed Management
Fund. This winter, Colorado State University and the Colorado Department
of Agriculture will hire a state noxious weed mapping specialist to
develop maps of the distribution of targeted noxious weed species
throughout Colorado....Good ArcView or ArcInfo skills are essential but so
are good communication skills.

For more information, contact Eric Lane.


2. Seeking case studies (Maryland)
From: Donnelle Keech (dkeech(at)tnc.org)

I am seeking case studies of invasive species control projects with
well-done monitoring components, for a session at the Mid-Atlantic Exotic
Pest Plant Council's August 2001 conference, *Invasive Plants: Taking
Action of All Fronts*. I am interested in any suggestions, but will be
especially excited about examples that are from the east, and were
accomplished with modest resources. If you or someone you know has an
illustrative monitoring and control project, please contact me.


3. Midwest invasive plant conference (Wisconsin)
From: Mariquita Sheehan (msheehan01(at)fs.fed.us)

The first day of this two-day conference (1-2 March, Eau Claire WI, $20
students/$40 non-student) is devoted to starting a state-wide weed council
for Wisconsin, a badly needed organization that will help Wisconsin weed
warriors pool their (meager) resources, team up with partners, and be more
efficient in getting the bad word out. So if you can only come for one
day I would encourage you to participate then. That said, both days are
worth it. Other organizations will be meeting too, including Prairie
Enthusiasts, WI Chapter of TWS, TNC.

To learn more, go to: http://www.plantsoutofplace.org/


4. Japanese hops (New York)
From: Cris Winters (cwinters(at)tnc.org)

Cris forwarded this question from a friend....

Have you had any experience with Japanese Hops (Humulus japonicus)? I
have a couple of riparian projects which will be starting this coming
spring, but there is hops everywhere. It appears the hops has killed many
of the young saplings in the original buffer area on the James River. I
am looking into the possibility of using some sort of herbicide to help
control in addition to physical removal. However, I would like talk to
someone who has actually done something with hops in past.


5. Recent weed articles (Nationwide)
From: John Randall (jarandall(at)ucdavis.edu)

1)Invasive plants versus their new and old neighbors: a mechanism for
exotic invasion. R.M. Callaway and E.T. Aschehoug. Science 290: 521-523
(Oct 20 2000).

It is often argued that invasive non-native species succeed because they
have escaped their natural enemies, however, the authors found that some
may also gain advantage by competitive interactions that native species
are not adapted to. In other words, the newcomers fight different than
the locals! TNC's own Eric Ashehoug (now on the Santa Cruz Island project
but at the time of this work a student at U Montana) and Ray Callaway of U
Montana found Centaurea diffusa had much stronger negative impacts on
native grass species it grows with in North America than on closely
related grass species from its original habitat in the Old World. The
differences appear to be due to differences in effects of C. diffusa's
root exudates on other species and how this effects competition for other

2)Biological control herbivores may increase competitive ability of the
noxious weed Centaurea maculosa. Callaway, R.M., T. DeLuca and W.M.
Belliveau. 1999. Ecology 80(4): 1196-1201.

Ray Callaway and colleagues found that when biocontrol insects (knapweed
root moth; Agapeta zoegana) fed on the roots of spotted knapweed (Centaurea
maculosa), neighboring Idaho fescue (Festuca idahoensis) plants actually
did more poorly than when grown with unattacked C. maculosa. Instead of
releasing the neighboring grass from competition and allowing to thrive as
intended, the insect had no detectable impact on knapweed and apparently
indirectly suppressed the fescue. Knapweeds fed on by another non-native
root feeder (Trichoplusia ni) it had smaller root systems and exuded more
total sugars than knapweeds protected from attack. The authors hypothesize
that moderate herbivory stimulated compensatory growth AND production of
defense chemicals that also had allelopathic effects or otherwise altered
the competitive relationship between the invasive knapweed and the native
bunchgrass. They also suggest that some other biocontrol agents could be
having indirect negative effects on some native species that are not yet

3)Mycorrhizae indirectly enhance competitive effects of an invasive forb
on a native bunchgrass. Marler, M.J., C.A. Zabinski and R.M. Callaway.
1999. Ecology 80(4): 1180-1186.

The authors found arbuscular mycorrhizae had no direct effects on either
the invasive non-native spotted knapweed (Centaurea maculosa) or the
native bunchgrass Idaho fescue (Festuca idahoensis) but apparently
increased the negative impacts of spotted knapweed on Idaho fescue when
the two plant species were grown together. This work was conducted in
pots but soil taken from the field was used to inoculate treated pots with
mycorrhizae. Idaho fescue plants grown with spotted knapweed without
mycorrhizae were 171% bigger than those grown with the knapweed and
mycorrhizae. On the other hand, spotted knapweed plants grown in
competition with Idaho fescue were 66% larger in the presence of
arbuscular mycorrhizae. These results suggest arbuscular mycorrhizae
strongly enhance the ability of spotted knapweed to invade North American

4)A test of community reassembly using the exotic communities of New
Zealand roadsides in comparison to British roadsides. J.B. Wilson et al.
2000. Journal of Ecology 88: 757-764.

In order to test competing theories about how plant communities come
together, the authors compared communities from roadsides in areas with
similar climates in Britain and in New Zealand where many species were
introduced from Britain. While there were some similarities, the authors
concluded 'that British species...in New Zealand assemble in communities
some of which are not known in Britain'. They note that this agrees with
evidence from the pollen and fossil record that although some communities
appear to be very old, their component species were usually present in
quite different assemblages in previous interglacial periods and even
several thousand years ago during the present interglacial. The results
are closest to the predictions of the Pre-adaptation hypothesis of
community assemblage since the British species apparently fit into niches
they hadn't met before arriving in New Zealand but for which they happen
to have the right characteristics. The results also provide partial
support for Stochastic and Deterministic hypotheses of community
assemblage but do not support the Alternative Stable States hypothesis.

5)Combining mowing and fall-applied herbicides to control Canada thistle
(Cirsium arvense) K. G. Beck and J.R. Sebastian. 2000. Weed Technology

Mowing one, two or three times before autumn applications of the
herbicides picloram (Tordon), chlorsulfuron (Telar), clopyralid+2,4-D
(Curtail) or dicamba (Banvel) provided inconsistent results and the
authors conclude that such a combination should not be commonly

Updated December 2000
©The Nature Conservancy, 1999