Newsletter Vol 20 Issue 2, 2012 – California Invasive Plant Council

Vol. 20, No. 2

Spring 2012

Cal-IPC News
Protecting California’s Natural Areas from Wildland Weeds
Quarterly Newsletter of the California Invasive Plant Council

Planting a Native Understory
In California’s Central Valley, River Partners has
been working to control invasive plants during
restoration projects along the Sacramento River by
establishing dense layers of native perennials, like
the gumplant (Grindelia camporum) shown above.
Learn more about their techniques on page 8.

Photo: River Partners

Inside:
The butterfly effect …………………………4
An ounce of prevention ……………………5
Stinkwort (Dittrichia graveolens) ………7
2012 Symposium …………………………. 10
Jepson Manual taxonomy changes…..13

From the Director’s Desk

Herbicides and butterflies
Cal-IPC
1442-A Walnut Street, #462
Berkeley, CA 94709
ph (510) 843-3902 fax (510) 217-3500
www.cal-ipc.org info@cal-ipc.org
A California 501(c)3 nonprofit organization

Protecting California’s lands and waters
from ecologically-damaging invasive plants
through science, educations, and policy.
STAFF
Doug Johnson, Executive Director

recent article in Science Daily reported on a university study, concluding that “three
commonly used herbicides can dramatically reduce butterfly populations.” An
article in the San Francisco Chronicle ran under the headline “Weed killers may spell
the end for butterfly” and claimed that herbicides “commonly used to control invasive
plants in the Bay Area also kill off butterflies.”
This is important news. It relates directly to an issue we covered in our last issue, the
protection of the endangered Lange’s metalmark butterfly, endemic to Antioch Dunes
Wildlife Refuge on the shore of San Francisco Bay. The butterfly’s host plant is being
crowded out by invasive plants like winter vetch.

Elizabeth Brusati, Science Program Manager
Alice Chung, Training Program Specialist
Heather DeQuincy, Outreach Program Manager
Ginny King, Program Assistant
Agustín Luna, Business Manager
Bertha McKinley, Program Assistant
Dana Morawitz, Mapping Program Manager
Cynthia Powell, Mapping & Modeling Specialist
Falk Schuetzenmeister, Mapping & Modeling Specialist
DIRECTORS
John Knapp, President
Native Range, Inc.
Jason Casanova, Vice-President
Council for Watershed Health
Doug Gibson, Treasurer
San Elijo Lagoon Conservancy
Julie Horenstein, Secretary
California Department of Fish & Game
Edith Allen
University of California-Riverside
Peter Beesley
Pacific Gas and Electric
Edmund Duarte
Alameda County Department of Agriculture
Jason Giessow
Dendra, Inc.
Kim Hayes
Elkhorn Slough Foundation
Sue Hubbard
Federal Employee
Shawn Kelly
Southern California Wetlands Recovery Project
Dan Knapp
Los Angeles Conservation Corps
Chris McDonald
UC Cooperative Extension
Peter Schuyler
Ecological Consultant

The articles remind us that habitat restoration requires difficult tactical choices, each
of which can have undesirable consequences. As the article on page 4 by the California
Department of Fish and Game’s Joel Trumbo points out, there are actions natural
resource managers can take to reduce the risk of such consequences.
The Chronicle article also reminds us that journalistic interpretations of scientific
studies commonly oversimplify the conclusions actually supported by the studies’
findings. In this case, the researchers used herbicide formulations that are not likely to
be selected for uses in sensitive butterfly habitat, and they applied herbicide directly to
the larval butterflies and their host plant, which would be avoided in a well-planned
restoration effort. Nor does the study distinguish whether impact to the butterflies
resulted from herbicide contact with the larval butterflies, ingestion of the herbicide, or
herbicide damage to the host plant.
Herbicides can be one of the best low-impact tools in the restoration toolbox. But
they need to be used wisely. Those working to steward wildlife habitat by removing
invasive plants are of course concerned about the potential wildlife impacts of any
tools they use. Beyond following the legal requirements of herbicide labels, there may
be additional practices that can be employed by natural resource managers to further
reduce potential for herbicide impact on wildlife.
That is why we are undertaking a project that will identify innovative practices
developed by longtime natural resource managers to reduce impact on wildlife. The
project will also engage an expert toxicologist to review common restoration uses of
herbicides to make recommendations for reducing potential wildlife impact. We intend
to publish the results in a “best management practices” manual which will share the
information widely within the restoration field. It continues to be our goal to ensure
that the latest available science on herbicide impacts be integrated into on-the-ground
management decisions in California wildlands.

Andrea Williams
Marin Municipal Water District
STUDENT LIAISONS
Chelsea Carey
UC Merced
Kai Palenscar
UC Riverside
Affiliations for identification purposes only.

Cal-IPC News

Spring 2012 – Volume 20, Number 2
Editors: Doug Johnson, Elizabeth Brusati, Heather DeQuincy
Cal-IPC News is published quarterly by the California Invasive
Plant Council. Articles may be reprinted with permission from
the editors. Submissions are welcome. Mention of commercial
products does not imply endorsement by Cal-IPC. We reserve
the right to edit all work.

Cal-IPC News Spring 2012

Day at the Capitol attendees successfully visited all 120 legislators this year.

Wildland Weed NewsNewsNewsNewsNews
Even Antarctica is not safe from invasive
plants. A recent article in the Proceedings
of the National Academy of Sciences
says that ecotourists and scientists have
accidentally transported seeds and other
material from thousands of plant species
to the bottom of the world. Warming
temperatures increase the possibility
that these plants will be able to establish
populations. During the 2007-08 summer
season, about 33,000 tourists and 7,000
scientists (including support personnel) landed in Antarctica, bringing an
estimated 70,000 seeds on their clothing
and other possessions. (Los Angeles Times,
March 6, 2012), www.latimes.com/
news/science/la-sci-antarctica-invasiveplants-20120306,0,4163406.story

Cal-IPC Updates
New BMP Manual released
Please see page 5 for a rundown
on Preventing the Spread of Invasive
Plants: Best Management Practices for
Transportation and Utility Corridors.
Day at the Capitol
Forty natural resource managers
visited Sacramento on March
14 to advocate for invasive plant
management funding and legislation.
AB 1251 will provide authority to
control South American spongeplant
in the Delta. Cal-IPC board members
visited agency executives, and

Help Cal-IPC Find a New Kind of
Board Member
Julie Horenstein
Board Development Committee
It probably comes as no shock that
the Cal-IPC Board of Directors has not
typically included people from the world
of large-scale corporate management,
finance, or public relations. But these
people may be increasingly important for
meeting Cal-IPC’s goals.

Screening horticultural plants for their
potential invasiveness may become even
more important as climate change drives
consumers towards purchasing more
drought-tolerant species. A team of researchers believes that more horticultural
species will be imported to the U.S.
from warmer regions such as the Middle
East and Africa. The researchers recommend that the USDA quickly adopt the
nursery stock screening procedures that
have already been proposed. (Frontiers
in Ecology and Environment 10: 20–28)
www.physorg.com/news/2012-01-ecologistsscreening-imported-invasive-species.html
In a strange example of interspecies
interactions, an invasive plant in
Australia appears to protect lizards

proposed that a definition of invasive
species be added to the Public Resources
code to enable stronger programs within
the Natural Resources Agency.
Staff changes
With the end of our ARRA grant, we bid
farewell to Training Program Manager
Jen Stern, Training Specialist Arpita Sinha
and Mapping Specialist Tony Morosco. We
appreciate all their contributions during
their time at Cal-IPC, and wish them well
in future endeavors!
Call for board nominations
Cal-IPC’s Board of Directors is accepting
nominations for new board members

Although Cal-IPC is quite successful
at obtaining government and foundation
grants, these grants typically only fund
specific projects, and Cal-IPC struggles to
cover administrative costs and activities
such as advocacy to support funding for
wildland weed management. Donations,
however, are typically unrestricted and can
be used to cover the gaps left by projectbased grants. Cal-IPC needs to cultivate
larger donors to effectively pursue its
mission of protecting wildlands from the

from an invasive toad. Cane toads are
an ecological nightmare in Australia,
where they were introduced to control
beetles. Instead, they poison native
Australian species that eat toads, including
the bluetongue lizard. Meanwhile, the
invasive plant mother-of-millions, also
eaten by bluetongues, produces a toxin
similar to the toads’. Bluetongue populations in areas with mother-of-millions
infestations have evolved to tolerate the
toxin. These populations are not in the
same areas as cane toads, but experiments
showed that these lizards can also tolerate
cane toad toxins. Researchers say it’s a
hopeful sign that bluetongues can adapt
to the presence of cane toads. (American
Naturalist, March 2012).
www.eurekalert.org

through July 1. Terms are two
years, beginning Jan. 1, 2013. The
board meets four times each year
throughout the state, and requires a
commitment to fundraising, working
on a committee, and organizing the
Symposium. Direct nominations and
questions to board@cal-ipc.org.
Call for student liasion nominations
The student chapter is accepting
nominations for liaisons to the
Cal-IPC board. Liaisons attend board
meetings in their part of the state and
help Cal-IPC serve students. Send
nominations to students@cal-ipc.org.

negative effects of invasive plants.
This summer the board will be
working with a consultant on our branding and outreach to potential donors. It
will be helpful to consider representation
from the corporate world on our board.
If you know someone with background
in corporate management, finance, law or
public relations who might be interested
in providing their perspective to the CalIPC board, please contact us at
board@cal-ipc.org. Thank you!

Cal-IPC News Spring 2012 3

The butterfly effect
by Joel Trumbo, Staﬀ Environmental Scientist, Lands Program,
Wildlife Branch, California Dept. of Fish and Game

wo recently published articles provide
a thought-provoking example of how
an invasive weed management tool might
be the best…or the worst… method for
protecting an imperiled wildlife species.
The Winter 2012 edition of Cal-IPC
News includes an article on how invasive
weeds are threatening the habitat of
several species, including the endangered
Lange’s metalmark butterfly (Apodemia
mormo langei). The imperiled butterfly
is found almost entirely at the Antioch
Dunes National Wildlife Refuge in
California’s East Bay region.
The article points out how
uncontrolled invasions of winter
vetch (Vicia villosa), yellow starthistle
(Centaurea solstitialis), and ripgut brome
(Bromus diandrus) have affected the
butterfly by out-competing its preferred
host, the naked stem buckwheat
(Eriogonum nudum psychicola). The article
mentions how refuge staff and volunteers
have used an integrated approach, which
includes herbicide applications, to control
the weeds.
About the same time the Cal-IPC
article came out, a study was published
by John D. Stark of Washington State
University, Puyallup, on the effects of
three herbicide products: Garlon® 4
(triclopyr ester), Stalker® (imazapyr) and
Poast® (sethoxydim) on Behr’s metalmark
butterfly (Apodemia virgulti). Stark used
A. virgulti as a surrogate species for the
endangered A. mormo langei. Stark’s paper
found a statistically significant decline
in adult emergence after the larvae were
directly exposed to herbicide sprays and to
herbicide residues in their food.
Stark’s study brings up several
important points. First, we need to
be cautious about assuming that the
herbicides we use are safe for wildlife.
While it’s true that the scientific literature generally supports the idea that
herbicides pose low risks to non-plant

Cal-IPC News Spring 2012

species like mammals,
birds and fish, the truth is
there aren’t many studies
about herbicide toxicity
to other groups like
reptiles, amphibians and
invertebrates. In fact, when
it comes to invertebrates,
the U.S. EPA requires
only one toxicity study
for registration, an acute
contact honeybee test.

The endangered Lange’s metalmark butterfly
The lack of invertebrate (Apodemia mormo langei) is threatened by invasive
toxicity data begs the
plants, but a recent study indicates that herbicides used
question: are honeybees
to control the plants could also harm the butterfly.
a suitable surrogate for
Potential impacts can be reduced by selecting the safest
assessing herbicide risks to
herbicide, avoiding application to the butterfly host
other invertebrates? Put in
plant, and planning application timing to avoid sensitive
the context of managing
life stages. Photo: Eric Palm, USFWS
for Lange’s metalmark
ingredients. This result occurs in spite of
butterfly, could the managers at Antioch
the presence of inert ingredients that are
Dunes assure themselves of the safety of
sometimes more toxic than the herbicides
their herbicide tools by taking a quick
themselves.
look at bee toxicity data? A review of the
available data for the three herbicides
The fish toxicity data, however, is a
is less than convincing. Two studies for
bit more interesting, especially if you look
sethoxydim, the active ingredient in
at the formulated products as opposed to
Poast®, do not indicate any significant
the active ingredients alone. According to
toxicological impact on bees. The U.S.
the available data, Garlon® 4, Poast® and
EPA reported that its one honeybee study Stalker® pose greater risks to fish than to
for triclopyr ester, the active ingredient in
other tested species, including honeybees.
Garlon® 4, was similarly without impact.
When it comes to fish toxicity, the U.S.
Finally, as for the third herbicide in Stark’s EPA considers 96-h LC50 values lower
study, imazapyr, data from the U.S. EPA
than 1 part per million (ppm) to be highly
suggests that the herbicide poses no
toxic. Poast®’s fish toxicity is roughly
significant toxicological risk to honeybees. between 1 and 3 ppm and Garlon® 4 is
In fact, the U.S. EPA goes on to suggest
even more toxic with values between 0.25
that, based on the numbers, honeybees
and 1.5. While no fish data is available
may be no more sensitive to imazapyr
for Stalker, a 2009 study by the California
than are vertebrates.
Department of Fish and Game revealed
Would other species be appropriate
surrogates to assess herbicide toxicity? The
available mammal and bird data reveal
that all three active ingredients are in the
U.S. EPA’s practically non-toxic to slightly
toxic ranges. The vertebrate toxicity data
for the formulated products appears
similar to the risk posed by the active

the product to be “slightly toxic” to
tadpoles (96-h LC50 15 ppm). While
not completely defensible scientifically,
at least with these three formulated
products, it appears fish toxicity could be
useful as a surrogate predictor for impacts
to butterflies.
…continued page 18

“An ounce of prevention”

“A

n ounce of prevention is worth a
pound of cure.” This philosophy
is as important in wildland stewardship
as it is in health care,. Preventing the
introduction of invasive plants is more
cost-effective than managing infestations
already established.
Throughout the last year, Cal-IPC and
partners have focused efforts on creating
prevention resources to reduce the spread
of invasive plants in California. This
has resulted in a new BMP Prevention
Manual, a list of weed-free forage and
straw providers, and a guide to weed-free
aggregate.

BMP Prevention Manual
Cal-IPC’s newest publication,
Preventing the Spread of Invasive
Plants: Best Management Practices for
Transportation and Utility Corridors,
presents voluntary guidelines to help
those managing transportation and
utility corridors in California prevent the
accidental introduction and spread of
terrestrial invasive plants.
Cal-IPC developed this new
prevention manual in partnership with
a technical advisory team of transportation and utility corridor management
experts from across the state. The
manual provides essential guidelines for
integrating prevention Best Management
Practices (BMPs) into transportation and
utility corridor planning, routine maintenance, project construction, revegetation
and landscaping activities.
Transportation and utility corridors,
strips of land upon which pipelines,
roads, and power or communication
lines are built and maintained, are
high-risk sites for the introduction and
spread of invasive plants. These corridors
provide opportunities for the movement
of invasive plants, as seeds and other
propagules can be transported by vehicles
throughout the corridors. Construction
and maintenance activities can introduce
or spread invasive plants through project
materials and ground disturbance. The

corridors may even cross geographic
barriers that previously limited the spread
of invasive plants.
However, transportation and utility
corridor managers can greatly reduce
the introduction and spread of invasive
plants by adopting prevention
practices such as cleaning
equipment and using weed-free
free
materials. Prevention BMPs that
minimize invasive plant spread
ad
in transportation and utility
corridors can also:
• Reduce future
maintenance needs
and cost
• Reduce fire hazards
• Reduce herbicide use
• Enhance visibility,
access and safety
• Limit liability for the
governing agency or
lessee
• Maintain good public
relations
• Protect wildlife
habitat, native plant
populations, and
beneficial insects, as
well as threatened
and endangered
species.

Weed-Free Forage Suppliers
UC Cooperative Extension, in
conjunction with the California
Department of Food and Agriculture
(CDFA) and County Agriculture
Commissioners throughout the state,
has created a list of Certified Weed-Free
Forage and Straw. Weed-Free Forage is
defined as hay, feed, or straw mulch that
has been inspected, and certified not to
contain propagative plant parts or seeds of
noxious weeds (as defined by CDFA, not
Cal-IPC’s Inventory). Available resources
on Cal-IPC’s website include: CDFA’s
weed-free forage inspection procedures,
a contact list for County Agricultural
Commissioners offering inspections,
and the list of certified weed-free forage
suppliers in California.

Weed-Free Aggregate
Aggregate, such as sand and gravel, can
also be a vector for the spread of invasive
plants. The National Park Service has
just completed a new guide for aggregate
users, Weed Free Aggregate for Land
Managers, which provides guidance for
starting a weed-free

aggregate inspection program.
For example, Garrett Dickman, a biologist
at Yosemite National Park, inspects
local gravel pits and works to create and
implement weed management plans at
aggregate production facilities, with the
goal of ensuring weed-free aggregate for
their construction and road projects.
Cal-IPC’s prevention webpage at
www.cal-ipc.org/ip/prevention includes
the new BMP Prevention Manual for
Transportation and Utility Corridors and
resources for weed-free materials.
The BMP Manual was funded
through the American Recovery and
Reinvestment Act, with funding provided
by the USDA Forest Service, State and
Private Forestry, through the California
Department of Food and Agriculture.

Cal-IPC News Spring 2012 5

“The torch has been passed”
An interview with Nelroy Jackson
by Gina Darin, California Department of Water Resources

ith a background in agriculture,
Nelroy Jackson dealt with weed
control in sugarcane at GuySuCo, a sugar
company in Guyana on the northern
coast of South America, then in California
crops while working for Monsanto®
in product development. Living in
California, Nelroy gained interest in
habitat restoration, especially as it relates
to forestry rangeland and wildfires. His
introduction to environmental weeds
came while using Roundup® to create
mosaics of understory vegetation to
reduce fire hazards.
Nelroy considers himself a hybrid.
He had to learn “how to work for a
chemical company and still be sensitive
to environmental health.” Because of his
interests, Nelroy was invited to give a
talk on herbicides at the first CalEPPC
symposium in Morro Bay. The event was
unique in that it started a dialogue among
people from different backgrounds – weed
scientists and ecologists.

Hopes in starting CalEPPC
Nelroy hoped that CalEPPC would
continue to encourage dialogue among
weed scientists and ecologists. He aimed
to take the conversation beyond absolutist
positions for or against herbicides and
biocontrol. He advocated for tolerance
and respect for opinions. In those early
meetings, everyone learned from each
other. “We became a very congenial
board. Meetings were long, but never
acrimonious.” The weed scientists and
ecologists ended up being friends.
Another goal Nelroy had was for
CalEPPC to become an advocacy
organization, which has been successful,
especially considering most scientists
are not trained in advocacy and many
advocates are not trained in science.

Advocacy
California Invsive Weeds Awareness
Day at the Capitol started because of

Cal-IPC News Spring 2012

the National Invasive Weeds
Awareness Coalition (IWAC)
and National Invasive Weeds
Awareness Week (NIWAW).
IWAC wanted to foster
advocacy and activities at the
state level, so California NGOs
“Do the doable!” Nelroy Jackson receiving
formed the California Invasive
Cal-IPC’s award for vision and dedicated service at
Weeds Awareness Coalition
the 2007 Symposium. Photo: Bob Case.
(CALIWAC) as an umbrella
organization to bring individual
regulations on water, and Caltrans has
groups together to focus on the state
jurisdiction over roads. In other states,
legislature. They decided to create what
these departments are often in the same
became “Day at the Capitol”. They
agency. Here NGOs like Cal-IPC need to
had support from a range of groups,
work with all three agencies to get invasive
such as Farm Bureau, the Cattlemens’
plant management implemented. State
Association, and the county Agricultural
employees can educate, but cannot lobby
Commissioners.
legislators.
Cal-IPC has also sent teams to
National Invasive Weeds Awareness
Week in Washington, D.C. In 2006,
Nelroy accepted an award recognizing
CALIWAC’s work in raising awareness
and public education related to invasive
plant management in the nation’s most
populous state. Nelroy was also given the
Lifetime Achievement Award, where it
was declared that “getting people together
is Nelroy’s specialty.”
California differs from other states
in that the Agriculture Department
enforces laws and regulations, while the
Natural Resources Agency has land and

Nelroy and Bob Pickard, Supervisor
in Mariposa County, were the key
CALIWAC members with advocacy
experience in the beginning. The rest of
the team, including Cal-IPC’s Executive
Director Doug Johnson, learned on the
job. The reason CALIWAC has been a
successful advocacy group is because many
individuals contribute from different
perspectives. “Relationships and mutual
respect make this team work.”

Nelroy got several Cal-IPC people
interested in NIWAW – Doug Johnson,
Bob Pickard, Jake Sigg (CNPS), John
Randall (The Nature Conservancy).
Cal-IPC has had relatively
large delegations to NIWAW
for a number of years – “it
was a good time to visit
some of the key California
representatives in an efficient
manner, and we had some
new folks like Elizabeth
Brusati and Gina Darin who
did excellent organizational
work.” Team CALIWAC built
relationships with staff for
Wendy West, Nelroy Jackson, and Jake Sigg
both Senators Feinstein and
represented California at the National Invasive Weeds
Awareness Week in Washington D.C., 2003.
…continued page 16

Stinkwort: history, research, and management
by Rachel Brownsey, Guy Kyser, and Joseph DiTomaso, UC Davis Weed Science

ittrichia graveolens (L.) Grueter
(stinkwort) is an annual
composite, native to the Mediterranean
region, that has spread rapidly in
California over the past two decades
(Figure 1). A nondescript, foul
smelling plant, stinkwort initially went
unnoticed by all but the most discerning
botanists and weed managers. An
early article in Madroño helped raise
awareness (Preston 1997), but stinkwort
has continued to spread mostly
undetected until recent years.

Number of California counties

possible hyper
accumulation
of heavy metals,
mercury, zinc,
and copper, at
abandoned mine
sites in Europe
(Higueras et al.
2003, Shallari
et al. 1998)
demonstrate a
potential to invade
areas with unique
soils. Stinkwort
Seeds disperse effectively along
flourishes both in
transportation corridors and establish
areas with very dry Dittrichia graveolens rosettes on a roadside in Davis, CA.
well in disturbed areas. This plant is now
conditions, and
and to the lack of published information
widespread in the San Francisco Bay
along the margin of wetlands. Presently,
on stinkwort.
Area and is expanding its range in all
invaded areas include gravel mines,
Management of stinkwort populations
directions. Collections have been made in roadsides, heavily grazed rangeland, and
has been challenging. If management
most Central Valley counties, along the
vineyard edges. Plants have also been
activities do not take place before plants
coast north and south of the Bay Area,
observed in both natural and constructed
begin to produce seeds in the fall, there
and in the Sierra Nevada foothills. There
wetlands, and on riparian floodplains.
is a risk that these activities will help
are also expanding populations in the San
Potential environmental and economic to disperse seeds rather than effectively
Diego area, thought to be from a separate
impacts of expanding populations in the
controlling the population. Additionally,
introduction.
state are not well understood. Negative
mowing on roadsides and other areas for
Stinkwort tolerates a range of
impacts documented in the scientific
fuels reduction in late spring potentially
soil conditions, temperatures, and
literature include livestock mortality
favors stinkwort by removing competing
precipitation regimes. Tolerance and
due to puncturing of internal organs
annuals while stinkwort is still small.
following seed
A more thorough understanding of
Dittrichia graveolens rate of spread in California
ingestion (Philbry
stinkwort biology and life cycle is
35
and Morton
needed to develop effective management
2000),
and
strategies.
30
contact dermatitis
Recent research
25
in susceptible
20
Over the past year and a half, we have
people (Thong
established
several field, greenhouse, and
et
al.
2008).
15
laboratory experiments at UC Davis. Our
However, impacts
10
to wildlife, natural goal is to investigate the environmental
5
characteristics that facilitate or limit
ecosystems, and
working landscapes establishment, growth, and reproduc0
1980
1985
1990
1995
2000
2005
2010
tion of stinkwort, and to characterize its
have not been
Year
life cycle and unique life history traits.
characterized on a
broad scale, owing What we learn about this plant will
Figure 1. The approximate rate of spread represented by the
help us (1) to predict which ecosystems
to the very recent
number of California counties where plant collections have
may be at risk of invasion, and (2) to
expansion of this
been made between 1984 and 2010 (California Consortium of
develop effective management tools.
plant in the state
Herbaria 2012).
A summary of the methods and early
…continued page 14

Cal-IPC News Spring 2012 7

Native understory controls weeds
by Heyo Tjarks, River Partners, Chico, California

ue to the construction of dams and
levees throughout the Central Valley
for agriculture and urban development,
current ecological conditions on most
of its floodplains do not favor the
establishment of
native woody or
herbaceous species.
Dams and levees have
altered the natural
hydrology (e.g. flood
frequency, duration
and amplitude) and
geomorphology (e.g.
sediment transport,
bank erosion, and
river meander) to
which native riparian
vegetation is adapted
and reliant upon
for reproduction
and successful
establishment.

aggressive approach of understory weed
management and the establishment of
an herbaceous layer consisting of native
perennials.

the project sites, and (3) create beneficial
wildlife habitat.

Before creating a field design, River
Partners biologists conduct an evaluation
to assess the site
conditions. These
include soil types,
topography, depth to
water table, current
vegetation, historical
vegetation, and
inundation intervals.
Once these variables
are understood, it
is possible to select
a suite of species
which are capable
of self-sustaining
growth within those
site conditions. In
addition, species
are chosen and
arranged based on
Because of
their benefits to
these alterations,
wildlife as well as their
native vegetation is
ability to compete
often outcompeted by Remnant vegetation and restoration sites at the San Joaquin River National
against non-native
aggressive weeds. Over Wildlife Refuge.
and invasive species.
the past few decades,
Once a suite of
restoration projects on the Sacramento
species is chosen, River Partners collects
Through experimentation, River
River have established approximately
and processes native seed from remnant
Partners has successfully germinated and
8,000 acres of riparian forests with native established several native herbaceous
vegetation within the project area or as
woody species. However the herbaceous
close to the site as possible in order to
species in the field, including mugwort
understory is frequently dominated by
ensure the genetic adaptation of the local
(Artemisia douglasiana), gumplant
annual grasses or other weeds including
ecotype.
(Grindelia camporum), telegraph weed
yellow starthistle (Centaurea solstitialis) or
(Heterotheca grandiflora), evening primrose
Next, we design the field layout.
milk thistle (Silybum marianum).
(Oenothera hookeri), western goldenrod
Design considerations include matching
(Euthamia occidentalis), creeping wild
Within the last decade, River
species’ growth requirements to the
rye (Leymus triticoides), and blue wild rye
Partners has strived to increase the
microsite conditions across the project
(Elymus glaucus), to name a few. We use
overall biodiversity and habitat structure
area and arranging species within this
an approach which combines modern
for the benefit of wildlife within our
framework to produce habitat structure
agricultural equipment and techniques,
restorations. Our goal is to design native
and food sources required by local wildlife
up-to-date horticultural knowledge, and
plant associations that will develop
species. Finally, the project area can be
adaptive
management
practices.
With
this
into sustainable communities through
prepared for planting using modern
combination, we are able to; (1) design,
ecological succession under the current
farming techniques including discing,
plant, and establish large acreages (up to
and projected future conditions. One
ripping, floating, pulling planting berms,
800 acres at a time) with multiple native
of our major advances toward this
and installing irrigation. Typically, a
understory species, (2) effectively control
goal has been achieved through an
project’s life is three years, in which the
non-native invasive weeds throughout

Cal-IPC News Spring 2012

site can be prepared, planted, maintained,
and established as a self-sustaining
community.
For example, on the San Joaquin River
National Wildlife Refuge (SJRNWR)
we are installing woody trees and shrubs
along the planting berms during the first
year of the project, followed by aggressive
weed control during the first two growing
seasons. Our weed control approach
involves flood irrigating the aisle-ways
between planting berms in order to
promote the germination and growth of
non-native and invasive species in the seed
bed. Then aisle-ways are disced or sprayed
with herbicide in order to exterminate the
weeds before they set seed.
Hand labor using backpack herbicide
sprayers removes weeds along the planting
rows where discing or broad herbicide
application would damage the planted
native woody species. This process is
repeated multiple times throughout the
first two growing seasons in order to
exhaust the existing seedbed. Ultimately,
this sterile seedbed approach reduces
competition for native grasses and forbs
that are broadcast or drill seeded at the
end of the second growing season.
After seeding native grasses or forbs,
the understory is actively managed during
the third and final year via irrigation,
mowing, and herbicide applications.
Adaptive management strategies and

“Pulling” planting berms on a restoration project to prepare for the planting of
woody trees and shrubs during the first year of the project.
timing are critical at this stage. For
example, it may be necessary to mow the
aisle-ways if significant weed pressure still
exists. If so, it is important to mow before
the weeds become so tall that mowing
creates a large amount of mulch that
will smother any smaller, native species.
Additionally, it is equally important to
cut the weeds low enough to reduce the
competition for sunlight with the native
species. Thus, choosing the optimal
timing and blade-height is key to a
successful mowing regime.

An endangered Least Bell’s vireo nest in a San Joaquin River National
Wildlife Refuge restoration site (2006).

In order
to facilitate
the use of
herbicides
for weed
control,
River
Partners
separates the
aisle-ways
into native
grass mixes
and forb
mixes. By
planting an
alternating
pattern of
forbs and
grasses, it
is possible

to add diversity and structure to the
restoration, while also allowing the use of
selective herbicides to combat weeds.
This approach has resulted in a dense
cover of native herbs, with 65% and 71%
absolute cover of native herbaceous species
and less than 4% absolute cover of weeds
on two fields surveyed in 2010. These
results are typical of many of our projects
in this region and more recent projects
implemented on the Sacramento River.
This method of understory
establishment has been employed by River
Partners since 2004. Since then, we have
restored approximately 1,700 acres of
riparian habitat on the SJRNWR alone.
This approach has not only been successful at combating non-native invasive
weeds, but the planted understories
have also been resilient to disturbances
including fires and long-duration flood
events. Lastly, the method has created
beneficial wildlife habitat. Over the past
decade, River Partners has documented
several threatened and endangered species
utilizing and breeding in our restoration
projects, including least Bell’s vireo,
western yellow billed cuckoo, valley
elderberry longhorn beetle, and the
riparian brush rabbit.
Heyo Tjarks can be contacted at
htjarks@riverpartners.org.

Cal-IPC News Spring 2012 9

Cal-IPC’s 21st Annual Symposium
Bay to Basin: Coordinating Response
to Invasive Plants across California
October 10 – 13, 2012

Wine Country Doubletree, Rohnert Park
Join us in Sonoma County, within
easy reach of the bay, ocean, Central
Valley (and, of course, great wine).
Sonoma County is known for its rustic
surroundings amidst the backdrop of
stately redwoods, rolling oak savannah,
and magnificient grasslands.
Join more than 300 natural resource
managers, researchers, students, and
restoration volunteers from throughout
the state to learn about and discuss the
latest in control techniques, research
results, while networking and mingling
during the awards banquet, social hour
and raffle, field course and field trips.

Discussion groups provide attendees the opportunity to interact with
experts while learning about special topics.

Including these sessions:
Working across Landscapes
Working across Taxa
Working across Time

Presentations
Discussion Groups
Awards Banquet
Exhibitors
Posters
Photo Contest
Raffle & Auction
10

Cal-IPC News Spring 2012

During the poster session attendees can interact with enthusiastic
researchers, students, and land managers presenting specific research.

Field Course
Wed. Oct 10th
Symposium
Thu. & Fri. Oct 11th &12th
Field Trips
Sat. Oct 13th
Field Course:
Wednesday, October 10th we will
host a field course which will include
a hands on section, similar to our
Habitat Restoration Workdays.
Attendees will leave with both new
information and innovative skills.
Register with the Symposium and
receive a discount!

The social hour is a great time to visit with colleagues, mentors, and new
friends while bidding on great raffle and silent auction items.

Discussion Groups:
These groups allow attendees to talk with each other and
experts on topics of particular interest. 2012 topics include
funding, protecting pollinators, prevention, Dittrichia
graveolens and careers.

Field Trips:
Saturday, October 13th half-day and full-day field trips
provide attendees the opportunity to see weed management
projects in the field. Locations include Mt. Tamalpais and
the Centennial of Marin Municipal Water Districts, native
grasslands and restoration and trip highlighting local
projects. (This year we probably won’t have to worry about
snow!)

Networking:
Mingle and network throughout the symposium breaks,
meals and social hour. The symposium is a great time to
renew your enthusiasm for natural resource management.

Continuing Education Units:

2011 Golden Weed Wrench Award Winner Sue
Donaldson at last year’s Symposium.

Every year Cal-IPC applies for continuing education units
(CEUs) from the California Department of Pesticide
Regulation and the Nevada Department of Agriculture.
We anticipate that we will be successful again this year and
will post the available hours on our website once they are
confirmed.

. . . See next page
More at www.cal-ipc.org
Cal-IPC News Spring 2012 11

More on the Symposium. . .
Registration, Transportation, Lodging

Call for Papers & Posters: Due June 15

Registration opens in June! Register online for faster
processing and choose from several payment options.
Registration includes meals, lodging, and 2013 Cal-IPC
membership.

Abstracts are due Friday, June 15. Submit abstracts for
oral papers (20 min.) or posters using the information at
www.cal-ipc.org/symposia/presenters.php. We especially
encourage submissions that address working across
landscapes, taxa, and time, or that emphasize how your
project can provide lessons to others. For more info
contact Elizabeth Brusati, edbrusati@cal-ipc.org.

Rates: Regular: $315 ($345 after Sept. 7, $385 on-site)
Student: $100 ($130 after Sept. 7, $170 on-site)
Symposium Volunteer: $210 (spaces fill early)
Restoration Volunteer: $210 (before Sept. 7 only)
Field Course: $155 ($175 without Symposium)
Getting There: Rohnert Park is located in Sonoma County,
one hour north of San Francisco and Oakland, two hours
north of San Jose, and one hour forty-five minutes west of
Sacramento. The Sonoma County Airport Express offers
transportation from the San Francisco International Airport
and the Oakland International Airport for $34/person each
way, no advance notice required. Information at
www.cal-ipc.org/symposia/attendees.php
Lodging: The Wine Country Doubletree offers single or
double occupancy rooms for a negotiated discounted rate of
$84/night. Attendees receive complimentary WiFi in every
room and free parking. Reserve your room through our
website by Sept. 7 to receive the discounted group rates.

Sponsorship Opportunities
Sponsoring the Symposium is a great way for your
organization to reach California’s natural resource managers
while supporting the event. Five levels of sponsorship offer
benefits including free registration, exhibit space, and
recognition in Symposium materials. Information at
www.cal-ipc.org/symposia/sponsorship.php

Student Contest
Students are invited to enter our fifth annual Student Paper
and Poster Contest. First place in each category receives
$250. First, second, and third places will be recognized at
the Symposium and in Cal-IPC News. www.cal-ipc.org.

Award Nominations: due July 9
The Symposium is an opportunity to honor individuals
and organizations who have made exceptional
contributions to invasive plant research or management.
We welcome nominations for: the Jake Sigg Award for
Vision and Service; the Golden Weed Wrench Award for
Land Manager of the Year; the Ryan Jones Catalyst Award;
the Invasive Plants Policy Award; and the Organization of
the Year Award. Send nominations to awards@cal-ipc.org.
See past honorees at www.cal-ipc.org/symposia/awards.php.

Photo Contest: Due September 7
Show off your photographic talents in the annual Cal-IPC
Photo Contest! Photos will be displayed at the Symposium
and attendees will choose Best in Show. Entries can include
specimen photos of individual plants, landscape photos, or
action photos of weed workers. We especially encourage
photos that illustrate the impacts of weeds. Send entries to
photos@cal-ipc.org.

Auction and Raffle
The Symposium is not just about learning the newest
research results and management techniques; it’s
also about having fun with fellow weed workers! Our
Wednesday night happy hour includes a raffle with a
variety of great prizes: tools, trips, wine, books, artwork,
clothing, and more. The banquet later in the evening
features a live auction of a few special items. Come mingle
with like-minded folks from around the state and recharge
your batteries. Contact raffle@cal-ipc.org if you have a
special item to contribute!
2011 field trip participants visit Grover Hot Springs State Park to
discuss eradication projects.

Cal-IPC News Spring 2012

Jepson Manual 2nd ed. invasive plant name changes
by Elizabeth Brusati, Cal-IPC Science Program Manager

otanists across California eagerly
awaited the release of the revised
Jepson Manual: Higher Plants of California
in January. Thanks to new research on
plant taxonomy, many familiar species
have new names. Some are even in
new families. Approximately 10% of
the species in the Cal-IPC Inventory
have new names, which we will be
incorporating into our materials. Below
is a description of the changes. First,
however, is a refresher course on the
Inventory itself.
The Inventory
The Cal-IPC Inventory is the
basis for everything we do. The Cal-IPC
Inventory uses a set of 13 questions to
assess whether a plant should be listed
as “invasive”. We define invasive plants
as those that “1) are not native to, yet
can spread into, wildland ecosystems,
and that also 2) displace native species, hybridize with native species,
alter biological communities, or alter
ecosystem processes.” Several thousand
naturalized plants grow in California
but few have impacts that justify adding
them to the inventory. The criteria system
was developed in conjunction with the
Southwestern Vegetation Management
Association in Arizona and the University
of Nevada Cooperative Extension. Our
goal was to create a transparent system
that clearly documents why a species is
listed, and to develop a procedure that
could be adapted to different states or
geographic scales.
To add a species, Cal-IPC staff or
a knowledgeable volunteer fills out a
Plant Assessment Form that lists a score,
description, and documentation for each
question. A committee of invasive plant
experts reviews species for their final
scores, which then determine the rating
of High, Moderate, or Limited. The
Inventory adds an “Alert” designation for
species with high or moderate impacts
that so far have a limited distribution in

Name changes for the Cal-IPC Inventory from the new Jepson Manual
Jepson Manual 1993

Common Name

Jepson Manual 2012

Arctotheca calendula (fertile)
Arctotheca calendula (infertile)
Cardaria chalepensis
Cardaria draba
Cardaria pubescens
Centaurea debeauxii

fertile capeweed
sterile capeweed
lens-podded white-top
hoary cress
hairy whitetop
meadow knapweed

A. calendula
A. prostrata
Lepidium chalepense
Lepidium draba
Lepidium appelianum
C. jacea notho subsp. pratensis

Centaurea maculosa
Chrysanthemum coronarium
Danthonia pilosa

spotted knapweed
crown daisy
hairy oat grass

C. stoebe subsp. micranthos
Glebionis coronaria
Rytidosperma pencillatum

Erechtites minima
Erechtites glomerata
Euphorbia esula
Linaria genistifolia subsp.
dalmatica
Lolium multiﬂorum
Nassella manicata
Picris echioides
Piptatherum miliaceum
Polygonum cuspidatum
Polygonum sachalinense
Retama monosperma
Sapium sebiferum
Taeniatherum caput-medusae
Vulpia myuros

Australian ﬁreweed
cutleaf burnweed
leafy spurge
Dalmatian toadﬂax

Senecio minimus
Senecio glomeratus
E. virgata
L. dalmatica subsp. dalmatica

Italian ryegrass
tropical needlegrass
bristly oxtongue
smilograss
Japanese knotweed
giant knotweed
bridal broom
Chinese tallowtree
medusahead
rattail fescue

Festuca perennis
Stipa manicata
Helminthotheca echioides
Stipa miliacea var. miliacea
Fallopia japonica
Fallopia sachalinensis
Genista monosperma
Triadica sebifera
Elymus caput-medusae
Festuca myuros

California but the potential to spread
widely. Earlier versions of the Inventory,
published in 1994, 1996, and 1999, were
less transparent because they did not use a
criteria system and did not document why
each species was listed.
Most of the current Inventory species
date to the last major update in 2006.
Additional species have been added since
then, including eight in 2011 (Cal-IPC
News, Fall 2011). Species are added when
Cal-IPC members provide information
that allow evaluation, but Cal-IPC does
not currently have a dedicated funding
source for the Inventory.

The Inventory does not cover plants
that are just beginning to become invasive
or species that are a problem in a very
limited area. Last year, we created the
Cal-IPC Watchlist (available at www.
cal-ipc.org/ip/inventory/weedlist.php) to
compile information on new plants of
concern. If you have a species you are
worried about, please send information
to Elizabeth Brusati, edbrusati@cal-ipc.
org. Another way to tell your fellow weed
workers about a new plant or to find
more information is the CalWeedTalk
listserv. Anyone on the list can post
to it; to join send a blank email to
…continued page 17

Cal-IPC News Spring 2012 13

…Dittrichia from page 7
results of these studies can be found in
the 2011 Cal-IPC Proceedings (www.
cal-ipc.org/symposia/archive/index.php).
In our second year of research, we have
established additional experiments
to investigate (1) the potential for
stinkwort invasion in grasslands using
a comparative study of root growth
observed with a minirhizotron system (a
specialized camera that is inserted into
an underground transparent plastic tube
at a 45° angle), and (2) an estimate of
population growth rate.

Life cycle
The stinkwort life cycle is
rather unusual, as all stages following
germination occur much later in the
season than from most annuals (Figure
2). Aside from tarweeds, there are
few comparable species in the native
California flora. However, weedy taxa
such as Salsola spp. (saltwort), Conyza
spp. (horseweed or fleabane), and to
some degree Centaurea solstitialis (yellow
starthistle) have similar life history
strategies.
Seeds are capable of germination
at nearly any time of year, but under
natural conditions, they tend to germinate
throughout winter and early spring
following precipitation. In the Central
Valley, germination is not limited by soil

majority of above-ground
growth occurs between June
and September, with the
largest increase in canopy
volume between August
and September. Flowering
and seed production occur
continuously from September
to December.

Discussion and
management
Seed viability for
mature, filled seeds is high
during natural dispersal in
the field, around 90% on
average. Seed germination
in the lab, under optimal
conditions for temperature
and moisture, is also
around 90%, and this rate
is observed for a wide range
of constant temperatures
from 12-34°C (54-93°F).
These results indicate that
Dittrichia graveolens (stinkwort) at UC Davis Weed
primary dormancy is very
Day 2011 with Rachel Brownsey.
unlikely. Additionally,
the high germination rate
establishing on riparian floodplains could
combined with the small seed
potentially spread to adjacent riparian
size suggests a short seed life. This has
forest ecosystems. The results suggest
important consequences for management
that stinkwort, like yellow starthistle,
of stinkwort populations, because it
implies that successful control efforts that will not be competitive in understory
communities of woodland and forest
prevent seed production for one to two
ecosystems due to limited growth in
years have potential to greatly reduce the
reduced light conditions.
population size.

Both the
greenhouse and the
Germination
Germination
Germination
field growth studies
extended into late
Moderated
Exponential
Rosette
Growth
summer, giving us
Growth
canopy growth
the opportunity
Flowering
to qualitatively
Reproduction
Seed Production
compare flowering
phenology of the
Dispersal
Dispersal
two populations.
Figure 2. Dittrichia graveolens life cycle based on field experiments in Davis, California.
Greenhouse plants
received daily
watering and moderate temperatures
temperature or low light conditions but
In a shade study conducted in the
of 29°C (85°F) day and 18°C (65°F)
rather by soil moisture. This is also likely
greenhouse we observed significant
night, while plants in the field received
to be true in coastal California and other
reductions in above- and below-ground
no supplemental water. All field and
areas of the state with moderate winter
growth of stinkwort under increasingly
temperatures. Following germination,
shaded conditions (50%, 27%, and 9% of greenhouse plants initiated flowering
during the first two weeks of September.
plants remain as small rosettes until
ambient light). This study was designed
mid-May when they begin to bolt. The
to address concerns that stinkwort plants
…continued page 17

Life Stage

Jan

Feb

Mar Apr May

dfadaf

Cal-IPC News Spring 2012

Jun

Jul

Aug

Sep

Oct

Nov

Dec

Shelterbelt
All-Terrain IPM
Services
www.ShelterbeltBuilders.com
Cal-IPC’s Habitat Restoration Workdays
Gain hands-on field experience controlling invasive
plants at Cal-IPC’s Habitat Restoration Workdays.
Discuss the theory behind various invasive plant
control techniques and practice these techniques
under expert guidance. These are half-day events
that are designed to be learning and volunteer
opportunities.

2012 Schedule
• Sat. June 2, Davis, Yolo County
Mechanical Control Tools for Arundo donax and Tamarisk
• Sat. July 14, Malibu, Los Angeles County
Residential Riparian and Upland Habitat Restoration
• Fri. August 24, Arcata, Humboldt County
Early Detection Mapping in Dunes Habitat
• Sat. September 29, Felton, Santa Cruz County
Woody Plant Control Tools at Old Quarry Site
• Sat. October 20, Chico, Butte County
Manual Invasive Tree Removal Methods
• Sat. October 27, Tiburon/Corte Madera, Marin County
Mapping Methods for New Invaders

Tarping to control purple velvet grass (Holcus
lanatus) during a Habitat Restoration Workday in
the Presidio, San Francisco.

• Sat. December 8, Big Sur, Monterey County
Control Methods for Cape Ivy and Periwinkle

…Nelroy Jackson from page 6
Boxer, as well as several representatives
(including Speaker Pelosi).
Nelroy shared advice for how local
weed workers can get elected officials
more interested in invasive plants as an
issue. “Foot work – write letters to the
editor of local newspapers, visit the offices
of elected officials and educate them.”
Nelroy recommended networking with
local organizations like RCDs, Caltrans
Supervisors and Landscape Architects, and
working with established organizations
like Cal-IPC, SERCAL, and CNGA on
their advocacy efforts.
Cal-IPC’s success shows other states
that persons outside of NAWMA and
state departments of agriculture or natural
resources could be effective in seeking

funds and legislation. Cal-IPC’s increased
role in policy is a logical progression
of the early board’s previous work. For
example, Doug’s position on CISAC
gives him a megaphone for his message
to the Agriculture, Caltrans, and Natural
Resources agencies. Nelroy believes that
advocacy should remain an important
part of Cal-IPC’s agenda.

and continue to form interagency
partnerships.

The Future

The original board members have
moved on, and it’s important to fill
those shoes. “We need to cultivate young
leaders.” Nelroy remembers J.P. Marie
attending the Invasive Plant School that
he and Carl Bell put on in Lake County
in early 2000s, and subsequently J.P.
became a Cal-IPC Board member.

Nelroy would like to see Cal-IPC
stay focused on the most important
issues and products – training new
people, maintaining the weed list, and
fundraising. Nelroy advocates for doing
the doable, and doing it now. “Studying
invasive plants is good, but doing
something about it is better.” Habitat
restoration is the goal, and we will succeed
as we prevent new weed infestations

Nelroy told me how heartwarming
it was to see so many young people at
the last few symposia he attended – “we
can’t leave a better legacy than that.”
Ideas live on as the next generation is
inspired, and Cal-IPC is a terrific model
for a sustainable society. As he let out a
chuckle, Nelroy said “I’m proud to be in
an organization without too much grey
hair!”

Thank You for Supporting our Work!
Recent Donors
Thank you! Your tax-deductible donations are
extremely valuable in supporting our programs.

Stewardship Circle ($1,000+)
Jake Sigg (San Francisco)

Patron ($500-$999)
Edith Allen (Riverside)
Peter Schuyler (Santa Barbara)
Andrea Williams (Richmond)

Champion ($250-$499)
Peter Beesley (Grass Valley)

Contributor ($100-$249)
Peter Brastow (San Anselmo)
Jamie & Ingrid Cabada (San Francisco)
Jason Casanova (La Crescenta)
Helen Conway (San Jose)
James Dougherty (San Francisco)
Doug Gibson (Encinitas)
Sue Hubbard (Salinas)
Barbara Meislin (Tiburon)

Friend (up to $99)
John Chamberlain (Half Moon Bay),
Carolyn Cromer (Louiville, KY), Ed
Duarte (Livermore), Jason Giessow
(Encinitas), Kim Hayes (Moss Landing),

Cal-IPC News Spring 2012

Julie Horenstein (Sacramento), Dan
Knapp (Los Angeles), Fred Kramer (San
Diego), Caroline Kuizenga (Carpinteria),
Chris McDonald (San Bernardino),
Robert Rutemoeller (Gualala), Jim Sharp
(Berkeley), George Strauss (Berkeley),
Lauren Velasco (Riverside), Peter Warner
(Santa Rosa), Georgie Waugh (Santa Rosa)

New Members
As a Cal-IPC Member, you join a powerful
network of land managers, researchers,
volunteers, and concerned citizens. Welcome!
Monica Arancibia (Cal. State Univ. San
Marcos, Encinitas), Rose Banks (Bishop),
Ezekiel Bean (City of Santa Cruz – Water
Depart.), Robert Berner (Marin Agricultural
Land Trust, Point Reyes Station), Catherine
Caldwell (DWR – Delta Ecosystem
Enhancement, Sacramento), Adam Cline
(Yocha Dehe Farm & Ranch, Brooks), Susan
Cohen (Martinez), Robyn Coole (Oceanside),
Ernestina Diaz (Sweetwater Authority, Spring
Valley), Tiffany Edwards (Duke University),
Jennifer Egawa (Caltrans, Berkeley), Scott
Gallic (RECON Environmental, San Diego),
Wayne Gilfillan (East Bay Regional Park
District, Castro Valley), David Greenberger
(Santa Cruz Sentinel), Mahala Guggino
(ESA, Lotus), Nancy Hartwick (Piedras

Blancas Lightstation, Morro Bay), Chris
Hoffman (Carson City), Sabrina Hopton
(McKinleyville), Libby Ingalls (San
Francisco), Shelley Lawrence (ECO Club,
CSUSM, Vista), Glen Lewis (Muir Heritage
Land Trust, Martinez), Monique Looney
(East Bay Regional Park District, Antioch),
Robinson Ngo (Hercules), Jonathan Pilch
(Watsonville Wetlands Watch), Lawrence
Ray (Scotts Valley Band of Pomo Indians,
Lakeport), Daydre Roser (Calif. Dept. of
Fish and Game, Elk Grove), Cathi Schrader
(County of Orange – OC Parks), Cindy
Sherwood (Cazadero), Thomas Smith
(Calif. Dept. of Forestry and Fire Protection,
Sacramento), Linda Stamer (USFS Big
Bear Ranger Station, Fawnskin), Katrina
Maria Steinhauer (Sanger), Joanne Taylor
(Orange County Parks), Lauren Velasco
(UC Riverside), Annie Walker (Placerville),
Kim Wehinger (City of San Diego), John
Willoughby (Placerville), Steve Windhager
(Santa Barbara Botanic Garden)

New Organizational Members
Organizational Members advance
Cal-IPC’s mission to protect California’s
wildlands from invasive plants.
Sweetwater Authority
The Santa Barbara Botanic Garden

…Dittrichia from page 14
We therefore concluded that photoperiod
is the likely signal for initiation of
reproductive growth, rather than drought
stress or temperature changes. This is
good news for planning management
activities, as we can expect flowering to
begin every year in early September under
a range of weather conditions. This will
allow managers to adjust their approach
and control methods accordingly.

for future investigation of specific management methods. If we expect to stop or
slow the spread of this plant in the state
we need effective management tools and
an informed management approach.

Resources
Consortium of California Herbaria. 2012.
Specimen records for Dittrichia graveolens.
Data provided by the participants of the
Consortium of California Herbaria (ucjeps.
berkeley.edu/consortium/).

The ongoing research is building our
understanding of the basic life cycle and
biology of stinkwort, allowing us to make
predictions of invasion potential that will
help prioritize management activities.
This information also lays a foundation

Higueras, P., R. Oyarzun, H. Biester, J. Lillo,
and S. Lorenzo. 2003. A first insight into
mercury distribution and speciation in soils
from the Almadén mining district, Spain.
Journal of Geochemical Exploration 80: 95-104

…Jepson from page 13

DNA evidence. The Jepson Manual uses
taxonomy based on monophyletic groups.
This means that the species in a particular
genus must be more closely related to each
other than to species in any other genus.
Some species have been lumped and some
have been split. For example, Cardaria
draba (hoary cress) has moved into the
genus Lepidium to become Lepidium
draba. Many families have been split.

californiaweedtalk-subscribe@topica.com.
The Inventory format may undergo
revisions in the future. We now have
better distribution information from
our mapping project of the past two
years, shown in CalWeedMapper
(calweedmapper.calflora.org). We also have
modeled the projected suitable range for
some species to predict where they might
be able to spread.

Changing Names
Cal-IPC’s Inventory generally
follows Jepson Manual nomenclature.
We will be integrating the new names
into our printed and online materials
while still referencing the older names.
Cal-IPC’s online Plant Profiles (www.
cal-ipc.org/ip/management/plant_profiles)
and CalWeedMapper now list both
the new and previous Jepson Manual
nomenclature. The online Inventory
database (www.cal-ipc.org/ip/inventory/
weedlist.php) still uses the old names
for now but new additions will use new
names.
We do not have space to provide a
detailed description as to why scientific
names change. However, in brief, plants,
like other organisms, were originally
classified based on shared physical
characteristics (i.e. they looked similar).
Some have now been reclassified based on

Philbry, A.W., and A.G. Morton. 2000.

Some name changes occur because
two taxonomists gave the same species
different names at different times. To
make them consistent, the oldest name
(the first one published academically)
takes priority and supersedes the newer
name. This is why the infertile (non-seed
producing) form of Arctotheca calendula
in California has now been recognized as
Arctotheca prostrata. Some name changes
correct misidentifications. Euphorbia esula
(leafy spurge) in California and elsewhere
in North America apparently is really
Euphorbia virgata.
Here is an example of how confusing
it can be to keep up with the changes:
One of the species added to the Inventory
in 2011 is Japanese or dwarf eelgrass,
Zostera japonica. A relatively new invader
to California, it was not included in the
1993 Jepson Manual. In the Inventory we
initially listed it as Nanozostera japonica
based on a new name in the USDA
PLANTS database (plants.usda.gov).

Pyogranulomatous enteritis in sheep due to
penetrating seed heads of Dittrichia graveolens.
Australian Veterinary Journal 28:858-860.
Preston, R. 1997. Dittrichia graveolens
(Asteraceae), new to the California weed flora.
Madroño 44:200-203
Shallari, S., C. Schwartz, A. Hasko, and J.L.
More. 1998. Heavy metals in soils and plants
of serpentine and industrial sites of Albania.
The Science of the Total Environment 209:
133-142.
Thong, H.Y., M. Yokota, D. Kardassakis, and
H.I. Mailbach. 2008. Allergic contact dermatitis from Dittrichia graveolens (L.) Greuter
(stinkwort). Contact Dermatitis 58:51-53

Rachel Brownsey can be contacted at
rnbrownsey@ucdavis.edu.

However, the new Jepson Manual keeps
it as Zostera. According to Dean Kelch at
the California Department of Food and
Agriculture Herbarium, “Nanozostera” is
not widely accepted. We have decided to
use Zostera japonica to be consistent with
the new Jepson Manual.
The article by David Magney, cited
below, provides a good description of why
names change. Additional information
came from the workshop “Phylogeny,
Taxonomy, and Name Changes in the
California Flora” at the Jepson Herbarium
at UC Berkeley.

Resources
Cockrell, C. 2012. California native-plant
classic gets a 21st-century makeover. UC
Berkeley News Center. newscenter.berkeley.
edu/2012/01/30/california-native-plant-classicjepson-manual-revision/ [Accessed April 4,
2012]
Jepson Flora Project. 2012 (v. 1.0). Jepson
eFlora. ucjeps.berkeley.edu/IJM.html. – This
online resource parallels the printed Jepson
Manual. It also provides a conversion list
for plant names from the first to the second
edition.
Magney, D. 2010. Why do those plant
names keep changing? Make up your minds
taxonomists! Channel Islands Chapter of the
California Native Plant Society. www.cnpsci.
org/html/PlantInfo/WhyPlantNamesChange.htm
[Accessed March 1, 2012]

Cal-IPC News Spring 2012 17

Readings &
Resources
Know of a resource that should be shared
here? Send it to edbrusati@cal-ipc.org.
Aquatic Plant Resources
A new blog from the Aquatic Plant
Management Society collects aquatic
plant management news from around
the country. It will be updated weekly
with articles on aquatic plant projects and
issues. apms-blog.blogspot.com
Eye on Invasives
The California Department of Fish
and Game offers a quarterly electronic
newsletter describing invasive species
work around the state. The Winter/Spring
2012 issue focused on invasive plants. To
subscribe, email invasives@dfg.ca.gov with
‘subscribe’ in the subject line.
www.dfg.ca.gov/invasives

…Butterfly from page 4
In the absence of species-specific
toxicity data for organisms like butterflies,
a practical approach might be this: avoid
using herbicides that have toxicity “red
flags” for non-plant species like fish when
there are sensitive invertebrates involved.
At least two of the herbicides in Stark’s
study could be replaced with less toxic
products that are based on the same active
ingredient or parent molecule without
sacrificing weed control efficacy. Garlon®
4 can be replaced with its low fish toxicity
cousin, the triclopyr amine Garlon® 3A;
and Stalker®, an emulsifiable concentrate,
can be swapped with one of the aqueous
imazapyr products that are practically non-toxic to fish (i.e. Habitat® or
Polaris®). As for Poast®, its aquatic toxicity
seems to be related to the inert ingredient,
naphthalene, which comprises about 80%
of the formulation. Unfortunately, there
is not a sethoxydim product that doesn’t
contain naphthalene, but perhaps another
grass-specific herbicide with low fish
toxicity could be used, like the clethodimcontaining product Envoy®.
Besides reducing risk by selecting less
toxic herbicides, it’s also possible to reduce

Cal-IPC News Spring 2012

State of the Estuary
Presentations from last fall’s State of the
San Francisco Estuary Conference are
now available, including videos from
plenary presentations on “The State of the
Bay: 2011” and “Doing More with Less:
Moving Toward Long-term Sustainable
Use of Delta and Bay Water”.
www.sfestuary.org/soe2011
Buy It Where You Burn It
“Buy It Where You Burn It” is a campaign
to prevent the spread of invasive species,
mostly insects and diseases, through
firewood. The California Firewood Task
Force describes the problem and provides
posters and videos on its website. There’s
even a fun game on the kids’ page!
www.firewood.ca.gov
Prescribed Burning
The Northern California Prescribed Fire
Council is a venue for practitioners, state
and federal agencies, academic institutions, tribes, coalitions, and interested
risk by reducing exposure. The first way
to do this is to avoid direct application or
significant drift to sensitive invertebrate
host plants. For example, Stark’s study
involves the direct application of the

When it comes to invertebrates,
the U.S. EPA requires only
one toxicity study for
registration [of herbicides], an
accute contact honeybee test.
herbicide to the caterpillars and their
food. This approach is reasonable if your
goal is to access risk using a worst-case
exposure scenario. But in reality, most
herbicide applications would not involve
spraying the host plants directly, if at
all. (While direct applications of the
grass-specific herbicide Poast® would
probably be harmless to naked stem
buckwheat, direct applications of Garlon®
4 or Stalker® would surely be fatal.) While
this type of exposure reduction doesn’t
completely eliminate risk, it would likely
increase the margin of safety considerably.

individuals to work collaboratively to
promote, protect, conserve, and expand
the responsible use of prescribed fire
in Northern California’s fire-adapted
landscapes. norcalrxfirecouncil.org
Weed Diagnostics
The Center for Invasive Plant
Management at Montana State University
hosts a new Invasive Plant Diagnostics
Listserv as a service to experts in weed
detection and identification nationwide.
Participants can request assistance in the
identification of unknown invasive plant
species and notify others of their findings.
Contact Elizabeth Galli-Noble, elizabeth.
gallinoble@montana.edu
Weed’s News
The Weed’s News is a free weekly digest
of invasive plant news delivered via email.
The website also contains Weed Risk
Assessment and job ads for those of you
looking to move to Australia.
invasivespecies.org.au/traction

Another way to reduce exposure is to
make herbicide applications when the
most sensitive invertebrate life stage is
not present. While an argument certainly
can be made whether or not the larval
life stage is more herbicide-sensitive than
other life stages, there’s little doubt that
the caterpillars are getting the greatest
feeding exposure. When it comes to
Lange’s metalmark butterfly, this time
period would probably be between the
September-October mating flights and
larval hatching that occurs during the
winter/spring. Combining this timing
strategy with avoiding direct applications
to host plants will significantly reduce
herbicide exposure to feeding caterpillars.

Resources
Fimrite, P. 2012. Weed killers threaten Lange’s
metalmark butterfly. San Francisco Chronicle.
April 2, 2012. Pg. C-1 Available: www.sfgate.com
Stark, J.D., X.D. Chen, C.S. Johnson. 2012.
Effects of herbicides on Behr’s metalmark
butterfly, a surrogate species for the endangered
butterfly, Lange’s metalmark. Environmental
Pollution. 164: 24-27. http://dx.doi.org/10.1016/j.
envpol.2012.01.011

Joel Trumbo can be contacted at
jtrumbo@dfg.ca.gov.

The WILDLAND WEED CALENDAR
May – July

August – December

Cal-IPC Field Courses
June 5-7
Idyllwild, Riverside County
www.cal-ipc.org

Ecological Society of America Annual Mtg
Aug 5-10
Portland, Oregon
www.esa.org/portland

Invasive Plant Ecology Short Course
June 26-28
North Platte, Nebraska
ipscourse.unl.edu

Rangeland & Livestock Management
Aug 20-31
Swanton Paciﬁc Ranch, Davenport
rrutherf@calpoly.edu

CNGA Grassland Ecology, Id & Monitoring
June 30
Mt. Tamalpais, Marin County
www.cnga.org

UC Davis Aquatic Weed School
Sept 5-6
Davis
wric.ucdavis.edu

N.A. Congress for Conservation Biology
July 15-18
Oakland
www.scbnacongress.org

Natural Areas Conference
October 9-12
Norfolk, Virginia
www.naturalarea.org/12conference

UC Davis Annual Weed Day
July 19
Davis
wric.ucdavis.edu

Cal-IPC’s 21st Annual Symposium
October 10-13
Rohnert Park, Sonoma County
www.cal-ipc.org

Aquatic Plant Management Society
July 22-25
Salt Lake City, Utah
www.apms.org

North American Weed Mgmt. Assoc. Conf.
October 29-November 1
Branson, Missouri
www.nawma.org

Russian River Watershed Symposium
November 2
Cloverdale
rrsymposium@yahoo.com
Central California Invasive Weed Symp.
November 8
Felton, Santa Cruz County
symposium@yahoo.com

2013
USDA Forum on Invasive Species
January 10-13, 2013
Annapolis, Maryland
www.nrs.fs.fed.us/disturbance/invasive_species/
interagency_forum/
California Weeds Science Society Conf.
January 23-25, 2013
Sacramento
www.cwss.org
Weed Science Society of America Meeting
February 4-7, 2013
Baltimore, Maryland
www.wssa.net

Quotable
“Our study identifies climate change as a risk [of increasing the
likelyhood of invasiveness], which combined with other factors is likely
to increase demand for imported heat- and drought-tolerant plants, but
this emerging threat is one that policy can effectively address.”
~ Bethany Bradley, ecologist at the University of Massachusetts Amherst. She continues, “The
USDA has tools to reduce import risk and we advocate that now is the time put them in place.
Pre-import screening has been tested in Australia for about 10 years now and it’s not foolproof,
but it seems to have done a good job of separating the really bad import ideas from more benign
introductions.” In “Ecologists call for screening imported plants to prevent a new wave of invasive
species” www.physorg.com/news/2012-01-ecologists-screening-imported-invasive-species.html, January
4, 2012.

Cal-IPC News Spring 2012 19

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