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Global Invasive Species Team listserve digest #121
Thu Oct 16 2003 - 14:31:00

1. Pathogen released to control yellow starthistle (California, USA)
2. Lehmann's lovegrass in Texas (Texas, USA)
3. Plant exchange agreements (Nationwide, USA)
4. Listserve correction regarding Phragmites (Nationwide, USA)
5. Seeking management recommendations (Michigan, USA)
6. Weed CD to be available in December (Nationwide, USA)
7. Literature Reviews (Global, Planet Earth)


1. Pathogen released to control yellow starthistle (California, USA)
From: Barry Rice (bamrice(at)ucdavis.edu)

A press release from the California Department of Food and Agriculture
notes that their biologists have been working on a natural fungal disease
(a rust, Puccinia jaceae) that is supposedly specific to yellow
starthistle (Centaurea solstitialis). This rust has been shown to be
unable to infect any of the nearly 100 other species of crops and native
plants it was tested on. It has been released in a valley in Napa County,
California, and is currently under additional study to observe its
efficacy and survival.

The original press release:


2. Lehmann's lovegrass in Texas (Texas, USA)
From: Bill Carr (bcarr(at)tnc.org)

Recently, a visitor to TNC's Dolan Falls Preserve along the Devil's River
in south Texas reported seeing Lehmann's lovegrass (Eragrostis
lehmanniana) somewhere on the ranch. My own view as a field botanist is
that Lehmann's lovegrass has not proven to be the problem in Texas that it
is in the desert southwest--at least not yet. It gets seeded by ranchers
from time to time, but it doesn't invade native grasslands in nearly the
problematic way that several other introduced grasses do. Out at Dolan
Falls, for example, Kleberg bluestem (Dichanthium annulatum), King Ranch
bluestem (Bothriochloa ischaemum), buffelgrass (Pennisetum ciliare) and
bermudagrass (Cynodon dactylon) are much much more abundant than Lehmann's
lovegrass, and we haven't figured out what to do about them yet. But from
what my colleagues say, it's only a matter of time before Lehmann's
lovegrass overtakes all those others to become Public Enemy Number 1.

Everything I've found on the web to date pertains to conditions in the
desert southwest. If you have any info about its invasive status in Texas,
I'd appreciate the news.


3. Plant exchange agreements (Nationwide, USA)
From: Jerry McCrea (gerald_mccrea(at)nps.gov)

In response to note #5 in the TNC Invasive Species Listserve Digest #120
(the question was about TNC having any plant exchange agreements with the
USFS or BLM), I thought you might be interested in an NPS example.

In the mid 1990s, an agreement was worked out between TNC and Big Thicket
National Preserve regarding Texas Trailing Phlox, which was (still is?) a
listed species. TNC was going to provide specimens to the Big Thicket
staff, who would transplant them in the park. Due to changes in job
responsibilities, I have lost track of this project, but you could contact
Big Thicket for an update.

**Note from listserve moderator---I have contacted Big Thicket staff and
am having a hardcopy of the agreement sent to me. If you want a copy,
contact me at bamrice(at)ucdavis.edu. Provide your hardcopy address, and I'll
send a copy of the agreement when it arrives.


4. Listserve correction regarding Phragmites (Nationwide, USA)
From: Barry Rice (bamrice(at)ucdavis.edu)

Entry #6 in Listserve Digest #120 had a slight error when discussing
the native and non-native strains of Phragmites australis in the USA.
Please note that the stems, especially just above the nodes, are smooth on
the native, ribbed on the exotic (and not smooth on the exotic, ribbed on
the native as noted in the listserve.

In the spirit of Soviet history, I have revised our listserve archives to
reflect the correct information. The error never occurred, comrade!


5. Seeking management recommendations (Michigan, USA)
From: Chad Avery (chad.avery(at)wmich.edu)

I am looking for control methods for the species listed below. We would
like to use the best management tools to control these weeds and if you,
or anyone else, could make specific recommendations I would appreciate it
greatly! The weeds are:

Abutilon theophrasti, Velvetleaf
Ambrosia artemissiifolia and A. trifida, Common and Giant Ragweed
Cirsium vulgare, Bullthistle
Conyza canadensis (Erigeron canadensis), Horseweed
Rumex crispus, Curly Dock
Solidago altisssima, Tall Goldenrod
Trifolium pratense, Red Clover


6. Weed CD to be available in December (Nationwide, USA)
From: Barry Rice (bamrice(at)ucdavis.edu)

Horace Skipper (skipper(at)clemson.edu) sent to me a brochure for a new CD
reference created by the Weed Science Society of America. The CD is called
"1,000 Weeds of North America: an identification guide." The cost is
US$54.95. I haven't seen the CD, but the brochure is nice! The CD will be
shipped 1 December 2003, but you can order now.

I have uploaded a pdf version of the brochure to:
where it will reside for at least a few months. Also, you can visit the
Weed Science Society of America web site (http://www.wssa.net) where at
some point in the future I expect the brochure will be publicized.


7. Literature Reviews (Global, Planet Earth)
From: John Randall (jarandall(at)ucdavis.edu)

Bramble, D.M. and J.C. Bramble. 2003. Vole and cattle: manipulating
herbivores to control invasive shrubs on rangeland (Utah). Ecological
Restoration 21(3): 218-219.

This short note suggests that voles and perhaps other small grazers may
have once played an important role in preventing dominance by woody shrubs
in some western grasslands and meadows, and may be able to do so again
under the right conditions. This suggestion is based upon observations the
authors made while attempting to restore a dry meadow complex in
south-central Utah. Persistent and often severe grazing since the late
1870s had resulted in extensive encroachment of woody native shrubs, first
by sagebrush (Atremisia tridentata) and then by rabbitbrush (Chrysothamnus
nauseosus), after prescribed fires had reduced the initial sagebrush
abundance. The authors reduced grazing rates by 50% or more and--perhaps
more importantly--shifted from the previous owner's regime of spring and
summer grazing to fall grazing. They soon noticed high rates of shrub
mortality and found that the rootstocks of the dead and dying plants had
been girdled, primarily by voles, although native rabbits and hares may
have contributed too. They speculate that the shift to fall cattle grazing
left more forage of both cool and warm season grasses for voles and other
small herbivores, whose populations then increased. However, the short
fall cattle grazing followed by the onset of winter sharply reduced forage
for these rodents who may have then turned to feeding on the shrubs to
tide them over. The authors suggest that managing large herbivores to
manipulate abundances of small grazers may be an inexpensive and
politically acceptable strategy for grassland and meadow restoration in
the region.

Kyser, G.B. and J.M. DiTomaso. 2002. Instability in a grassland community
after the control of yellow starthistle (Centaurea solstitialis) with
prescribed burning. Weed Science 50(5): 648-657

The authors treated a northern California grassland dominated by the
invasive weed yellow starthistle (Centaurea solstitialis, hereafter YST)
with prescribed fire for three consecutive years and then tracked the
abundance of the YST and other plants there and in an unburned control
site for four more years in order to determine if the effects of the
burning lasted or were transient. Immediately following the third year of
prescribed fire YST abundance had decreased significantly (seedbank,
seedling density, and mature vegetative cover were reduced by 99%, 99%,
and 91% respectively) while native perennial grasses and forbs,
particularly legumes, had increased relative to pre-burn treatment levels.
However, the authors found that these effects were relatively transient
and YST abundance was rapidly increasing towards pre-treatment levels
while native species abundance was decreasing towards those levels by the
third year after the burns. In fact, cover of native forbs plunged well
below pre-treatment values by the third and fourth year after the burns.
However, although YST seedbank and seedling abundance approached
pre-treatment values by the end of the study, cover of adult YST never
increased above 40% of the pre-treatment values. This study indicates
that three consecutive burns did not establish a stable new community
dominated by desirable native species and with low YST abundance as had
been hoped. However, it leaves open the possibility that periodic (e.g.
every 3-10 years) re-treatment with fire might result in acceptably high
native species abundances and low YST abundance at this grassland, and
perhaps in other similar northern California grasslands.

Updated January 2004
©The Nature Conservancy, 2003