Vol. 24, No. 2
Summer 2016
Cal-IPC News
Protecting California’s Environment and Economy from Invasive Plants
Newsletter of the California Invasive Plant Council
Celebrating
park stewardship
Sarah Minnick, Stewardship Coordinator of
Ring Mountain Preserve for Marin County
Parks, with a young volunteer.
Testing oxalis control 4
Celebrating park stewards 8
Soil bacteria vs. invasive grasses 9
New threat to forests 10
WMAs: Who needs’em? 11
From the Director’s Desk
Rats on islands
By Executive Director Doug Johnson
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
Protecting California’s environment and economy
from invasive plants
STAFF
Doug Johnson, Executive Director
Elizabeth Brusati, Senior Scientist
Agustín Luna, Director of Finance,
Operations & Administration
Bertha McKinley, Program Assistant
Dana Morawitz, Program Manager
for GIS and Regional Conservation
BOARD OF DIRECTORS
Jutta Burger, President
Irvine Ranch Conservancy
Gina Darin, Vice President
California Department of Water Resources
Steve Schoenig, Treasurer
Independent Consultant
Tim Buonaccorsi, Secretary
RECON Environmental, Inc.
Jason Casanova, Past President
Council for Watershed Health
Jennifer Funk, Chapman University
Jason Giessow, Dendra, Inc.
William Hoyer, US Navy
Shawn Kelly, Southern California Wetlands Recovery Project
Drew Kerr, Invasive Spartina Project
Ed King, Placer Co. Ag. Commissioner’s Office
Dan Knapp, Long Beach Conservation Corps
John Knapp, The Nature Conservancy
Laura Pavliscak, Tejon Ranch Conservancy
Heather Schneider, UC Santa Barbara
Lynn Sweet, UC Riverside
I
slands invaded by rats are some of the clearest examples of invasive species’ impact
to biodiversity. They are also among the best examples of the potential benefits of
eradication.
Islands have historically provided critical breeding habitat for seabirds. And because
of their isolation, they hold a preponderance of the world’s endangered biodiversity. As
sailors circled the globe and visited remote islands, they inadvertently spread rats, which
prey extensively on chicks and eggs and damage vegetation. In one example, Australia’s
Lord Howe Island in the South Pacific, 30 wildlife species have disappeared since rats
arrived in 1918.
New Zealand started working on this problem some 40 years ago. To date, over 400
islands have been cleared of rats. The typical technique is spreading poisoned bait from
the air. Groups like Island Conservation, headquartered in Santa Cruz, are taking the
work global. Their projects span from protecting black oystercatchers in the Aleutian
archipelago to the endangered Peruvian diving petrel on Choros Island off the Chilean
coast.
Most recently, the world’s largest ever rodent extermination was completed in 2015,
removing rats from South Georgia Island in the south Atlantic. About 95% of the bird
life has been lost due to rat depredation, but with time, is expected to recover. In a sign
of things to come, the world’s most southerly songbird, the endemic South Georgia
pipit, was found for the first time in living memory to be nesting on the main island.
Few invasive species control efforts are as clear-cut as removing rats from islands. For
invasive plant control efforts , we are tasked with sorting through the severity and types
of impacts and the feasibility of control, and putting that all into the context of what’s
best for an evolving ecosystem. Still, the principle is the same, and it’s great to see the
potential for success.
For a detailed telling, see William Stolzenburg’s 2011 Rat Island: Predators in
Paradise and the World’s Greatest Wildlife Rescue. Visit Island Conservation’s website at
www.islandconservation.org. And see a video of results ten years after removal of rats
from Anacapa Island (pictured below) in the Channel Islands off the California coast at
www.youtube.com/watch?v=RDJgMt19GRI.
STUDENT LIAISONS
Marina LaForgia, UC Davis
Amanda Swanson, UC Riverside
Cal-IPC News
Summer 2016 – Vol. 24, No. 2
Editors: Doug Johnson & Elizabeth Brusati.
Published by the California Invasive Plant Council. Articles
may be reprinted with permission. Previous issues are archived at www.cal-ipc.org. Mention of commercial products
does not imply endorsement by Cal-IPC. Submissions are
welcome. We reserve the right to edit content.
2
Cal-IPC News Summer 2016
Channel Islands Restoration
Affiliations for identification purposes only.
Cal-IPC Updates
Symposium program set. Join us near
Yosemite for the 25th annual Cal-IPC
Symposium! More details page 6.
Submit photos and videos. Joining our
annual Photo Contest is our new “Weed
Workers of California” video project. We
want to hear from weed workers around
California about the work you do and
why it’s important to you. Send your
video of up to 60 seconds from the field
(or the lab). See links for Photo Contest
and Video Submission on the Symposium
webpage. Open July 15-Sept. 15.
Mapping arundo in the Central Valley.
Cal-IPC and project partners including the Sonoma Ecology Center, River
Partners, and the California Dept. of
Water Resources are mapping giant reed
(Arundo donax) across the San Joaquin
and Sacramento River watersheds using
aerial imagery.
Screening underway for emerging
weeds. Cal-IPC has begun screening
200 watch list species to determine
their potential for becoming invasive in
California.
Algerian sea lavender being treated.
Cal-IPC is controlling invasive Limonium
ramossisimum at ten salt marsh sites
around San Francisco Bay. This species is
a relatively new invader of upper marsh
habitats and has been spreading.
Nature Reserve of Orange County.
Cal-IPC is delivering a five-year plan for
invasive plant management and early
detection/rapid response (EDRR) for the
17,000-acre Coastal Subregion of the
reserve.
Media contacts. High Country News
interviewed Cal-IPC about invasive plants
and climate adaptation, and Bay Nature
interviewed us about how new gene drive
technology might impact invasive species
management.
Spreading the word. We presented a at
the SERCAL restoration conference in
North Lake Tahoe, exhibited at the Bay
Area Open Space Council’s annual conference in Richmond, and gave out “Don’t
Plant a Pest!” brochures at the Roseville
Greener Garden Expo.
Wildland
Weed News
California Invasive Species Action
Week. The California Department of Fish
and Wildlife sponsored the second annual
CISAW June 4-12. To see what happened
and get ideas for next year, go to www.
wildlife.ca.gov/Conservation/Invasives/
Action-Week
Spring campaign a success. Thanks
to everyone who contributed, we raised
$46,000 in May to
support an update
to the Invasive
Plant Inventory
and other Cal-IPC
work. Thank you!
If you missed the
Spring Campaign,
you can support
Cal-IPC through
our San Francisco
Marathon runners!
www.crowdrise.
com/cal-ipc1.
concentrations found that snails could
survive in many conditions, but their reproductive output was low in both natural
waters and experimental low-calcium conditions. The results suggest that naturallyoccurring differences in water chemistry
may reduce the spread of mudsnails in
the park. Vazquez et al. 2016. Biological
Invasions. 18(6):1523-1531.
Homeowners willing to have invasive
trees removed. A study in South Africa
surveyed homeowners who had invasive
trees in their gardens. More homeowners who had had exposure to media
on invasive species knew their tree was
Other News
WHO clarifies:
Shelley Phillip and Cal-IPC Vice-President Gina Darin handed
glyphosate not
out Cal-IPC information at the Roseville Greener Garden Expo.
a risk. A joint
statement from
invasive. While most were not interested
the United Nations and World Health
in removing the tree themselves, most
Organization (WHO)says that glyphosate (83%) said they would be willing to have
(the active ingredient in RoundUp
the tree removed if it was taken down at
herbicide) does not pose a cancer risk,
no charge by an appropriate agency. The
clarifying the confusion over the WHO’s
study was conducted in conjunction with
recent designation of glyphosate as a
new regulations that went into effect in
carcinogen. For an explanation of the the South Africa in 2014. Shackleton, C.S.
difference between hazard potential and
and R. T. Shackleton. 2016. Biological
actual risk, see www.wired.com/2016/05/
Invasions. 18(6):1599-1609.
monsantos-roundup-herbicide-cause-cancernot-controversy-explained/
Stopping mudsnails in Redwood
National Park. New Zealand mud
snails are exotic mollusks present in
many waterways of the western United
States. In northern California’s Redwood
National Park they were first found in
2009. A study testing the response of
snails to water conductivity and calcium
Keep current…
…on the latest happenings in the
weed world by keeping your Cal-IPC
membership up to date! Check your
membership status on the mailing
label of this newsletter. Renew online
or with the enclosed envelope. Thank
you for supporting our work!
Cal-IPC News Summer 2016
3
Oxalis pes-caprae control trials
By Lew Stringer, Restoration Ecologist, Presidio Trust, LStringer@presidiotrust.gov
T
ype Oxalis pes-caprae into the search
bar of online mapping tools like
Calflora or iNaturalist and you will see
an almost solid line of occurrence points
that run the length of the California coast
from Tijuana estuary at the Mexican
border to Lanphere dunes in Humboldt
County. Imagine clicking on each of
those points to reveal a trove of hidden
photos, like a database subconscious,
of managers wringing their hands and
waving herbicide wands at this rapidly
wandering weed. You would have found
a picture of me in 2004 standing over a
clip board scheming an end to its crowding out of the little rare annuals that
we try to protect in the Presidio of San
Francisco.
Native to South Africa, oxalis has
spread to all Mediterranean climate
regions of the world. It has been observed
forming dense carpets in plant communities such as grasslands and sand dunes
that harbor rare and endangered plants.
In the late nineties and early aughts, our
stewardship program spent many hours
of staff and volunteer time ineffectively
hand weeding oxalis from areas managed
for rare annuals. To improve our management we conducted two informal trials
in the Presidio to compare the efficacy of
mechanical, cultural and chemical controls of oxalis. In the first trial in 2004,
we measured the impact of hand weeding
versus tarping on oxalis cover and density.
A follow up study was conducted in 2009
to test the efficacy of herbicide on those
parameters.
Methods
2004 Manual Trial: At two sites in
the Presidio (sand dune and serpentine
grassland) 18 permanent 0.5 x 0.5 m
plots were established in January 2004.
Plots were located in areas where O.
pes-caprae percent cover was relatively
high. Six treatments (including control)
with 6 replicates were randomly assigned
to the 36 plots (see table). Prior to the
4
Cal-IPC News Summer 2016
application of treatments,
baseline measurements were
taken in all 36 experimental
plots. Percent canopy cover
for O. pes-caprae was estimated
over the 0.5 x 0.5 m area of
each plot and O. pes-caprae
stem density was counted.
In February 2004, prior to
corm formation, all manual
treatments were applied. In
plots receiving the pick
treatment, O. pes-caprae was
removed by hand with the
assistance of a hand pick.
Plots receiving the hula-hoe
treatment were scraped with a
hula-hoe. All vegetation and
approximately 3 cm of top soil
were pulled from the plots in
this treatment. The scraped
material was then removed
from the sites. One set each
2010.
Counting oxalis stem density.
of the pick plots and the
hula-hoe plots received a
repeat treatment one month
Results and Discussion
later. Plots receiving the tarp treatment
were covered with Lumite® 300, black
2004 Manual Trial: Tarping was the
UV stabilized polypropylene shade fabric
only treatment that significantly conand pinned with metal fabric stakes. The
trolled oxalis in the 2004 study. When
tarps were removed in October 2005.
the Lumite tarps were removed in late
Stem density and percent cover were
October 2005 after 9 months staked to
re-measured in January 2005.
the ground, etiolated shoots could be
2009 Herbicide Trial: Twenty permanent 1 m x 1 m plots were established
in November 2009. Plots were located
in areas where O. pes-caprae percent cover
was relatively abundant. Four herbicide
treatments with 5 replicates were
randomly assigned to the 20 plots. On
November 25, 2009, prior to the application of treatments, stem density was
counted from a 0.5 m x 0.5 m quadrat
at the center of each 1 m2 plot to reduce
edge effects. On December 17, 2009,
prior to corm production, all herbicide
treatments were applied by Shelterbelt
Builders to randomly assigned 1 m2 plots.
Stem density was recounted in December
observed having recently germinated from
corms. Most of these shoots were unable
to recover. (See figure next page.)
The results of this study and subsequent tinkering with tarping has refined
our management of oxalis. We now use 6
mm polyethylene black sheeting instead
of Lumite® as it is more effective at blocking photosynthetically active radiation.
Timing is also important. Tarping is now
done in early to late-November or about
4 weeks after oxalis has emerged with
fall rains. At this life stage, most oxalis
corms have germinated and have used up
the carbohydrate reserves stored in below
ground corms. New corm formation has
not yet begun at this stage. Most oxalis
stems die within 6 to 8 weeks of tarping.
Collateral damage to desirable vegetation
makes this treatment undesirable in
certain areas, however we have observed
that several species of perennial forbs
and grasses are able to recover after being
covered for the 8 week duration needed to
eliminate oxalis.
2009 Herbicide Trial: A significant
change in O. pes-caprae stem density was observed between pretreatment
(November 25, 2009) and a year after
treatment (December 1, 2010). It was
a mistake not to include a control in
this trial; however, unquantified visual
observations of surrounding untreated
areas, while anecdotal, showed much
higher density than those in plots. A
one-way analysis of variance revealed a
significant difference between the change
in mean number of oxalis individuals
pre- and post-treatment (p<0.05). Only
Treatment B was significantly different
that Treatments A, C and D in 2010.
2004 Manual Trial
Treatments
2009 Herbicide Trial
Treatments
1) control (no treatment)
A) 1% Garlon 4 Ultra + Competitor
2) hula-hoe
B) ½% Garlon4 Ultra + Competitor
3) repeat hula-hoe
C) 1% RoundUp Pro Max + Trifol water
conditioner
4) hand pick
D) 1% Rodeo Aquamaster + Syltac +
Trifol water conditioner.
5) repeat hand pick
6) tarp
Note: We did not include a “no treatment”
plot
It is often helpful to identify the least
amount of herbicide necessary to provide
effective kill. One important finding is
that ½% Garlon4 Ultra with Competitor
was significantly less effective than 1%.
While, there was no significant difference
between the effectiveness of 1% Garlon4
Ultra with Competitor and 1% RoundUp
Pro Max + Trifol water conditioner and
1% Rodeo Aquamaster + Syltac + Trifol
water conditioner, 1% Garlon4 Ultra with
Competitor had the smallest variance in
its effectiveness, with plots that ranged
from 2-12 individuals after treatment.
The Rodeo and Roundup treatments
both had plots with outliers in the high
20s. Having included a higher number of
replicates in this study may have provided
better clarity.
While this experiment only tested
the effects of each herbicide treatment
on Oxalis, the known impacts of each
herbicide on other plants and animals
provides greater flexibility when working
to control Oxalis in different situations.
Effects of Manual and Herbicide Treaments
on Oxalis pes-caprae Density
200
Pre treatment mean + standard deviation
180
Post treatment mean + standard deviation
Oxalis individuals/ 0.25m2
160
140
120
100
80
60
40
20
0
Hula Hoe Hula Hoe Hand Pick Hand Pick
Repeat
Repeat
Manual Treatments (2004,2005)
Tarp
A
B
C
D
Herbicide Treatments (2009,2010)
Cal-IPC News Summer 2016
5
Celebrating Park Stewardship
25th Anniversary
Cal-IPC Symposium
Nov. 2-5, 2016
Tenaya Lodge
Program Highlights
Plenary sessions focus on invasive plant management as an integral part of park stewardship, with speakers including:
Don Neubacher, Superintendent of Yosemite National Park
Terri Hogan, National Invasive Plant Program Manager, National Park Service
Jay Goldsmith, Natural Resources Division Director, Pacific West Region, National Park Service
Jay Chamberlin, Natural Resources Division Chief, California State Parks
Mark Hylkema, Santa Cruz District Archaeologist & Tribal Liaison, California State Parks (on cultural resources)
Katherine McEachern, Ecologist, US Geological Survey (on intersection with listed species)
Mary Beth Hennessy, Deputy Director, Ecosystem Planning, US Forest Service (on intersection with wilderness designation)
Jun Kinoshita, Fire Archeologist, National Park Service (on intersection with fire management activities)
Dozens of other speakers and poster presenters will share findings on the latest in management techniques, research, and related land
management topics. Continuing education credits will be appliced for from the California Dept. of Pesticide Regulation (12 units
Other/2 units Laws & Regs )and Nevada Dept of Agriculture. Final program to be posted on Cal-IPC website in July!
6
Cal-IPC News Summer 2016
Registration Open!
Early-bird rates through Sept. 15. Member: $295 / Non-Member: $350 / Student: $50
Register online at www.cal-ipc.org/symposia
Trainings (Nov. 2)
Using Certified Weed-Free Forage and Mulch (11am-5pm, $60): Straw mulch used in
restoration projects can introduce weed seeds. So can hay used for horses or livestock. Learn
how to specify, source, and inspect hay or straw for use in wildlands.
Calflora’s Weed Manager Applications (1-5pm, $50): Map weeds on a smartphone and
track treatment, using a custom interface designed for your organization? Calflora’s Weed
Manager suite of tools is designed to do this and more.
Invasive Plant Management 101 (11am-5pm, $60): New to the field, or never got a full
background on weed management? Get context for plant ID, weed biology, mapping,
strategic prioritization, IPM control approaches, monitoring, permitting, and more.
Field Trips (Nov. 5)
Sierra National Forest and Nelder Grove of Giant Sequoias (8:30am-12:30pm, $25) Join
Forest Service natural resource managers to visit the leading edge of yellow starthistle and
medusahead moving up into the mountains, and walk in the giant Sequoias.
Merced River Canyon (8:30am-4:30pm, $50) See where a multi-agency campaign has
knocked back dense infestations of yellow starthistle, Italian thistle and tree-of-heaven,
including extraordinary treatments on steep rocky slopes using rope systems and highpowered truck-mounted spray rigs.
Hunting for invasive blackberry in El
Capitan Meadow. Photo by Garrett Dickman,
Yosemite National Park.
Yosemite Valley Tour – Weeds and Waterfalls (8:30am-4:30pm, $50) See Yosemite Valley
through the lens of three invasive plant challenges: Himalayan blackberry, velvet grass, and
annual grasses. and hear about research on native genotypes resilient to climate change.
Plus…
Discussion Groups Poster and Exhibitor
Session Student Paper and Poster Contests
Student Chapter Lunch Awards Banquet
Social Hour with Auction & Raffle
Photo Contest and Video
Montage!
Submit your best photos (weed workers, scary
infestations, specimen shots, humor, before
and after) to our annual Photo Contest. Your
contributions help Cal-IPC communicate about
the work you do.
And new this year, submit a short (up to
60 second) video for our “Weed Workers of
California” montage. We want to hear about
the work you do and why it’s important to you.
Details at www.cal-ipc.org/symposia.
Both open July 15 to Sept. 15!
Golden Gate National Parks Conservancy interns pull yellow starthistle. 2014 CalIPC Photo Contest. Photo by Suzanne Whelan, Marin Municipal Water District.
Cal-IPC News Summer 2016
7
Celebrating park stewards
O
ur 2016 Symposium celebrates
park stewardship in honor of the
National Park Service’s Centennial. We
asked a few Cal-IPC members about their
work in national, state, and local parks.
Athena Demetry, Restoration
Ecologist, Sequoia and Kings
Canyon National Parks
In 2001, I ushered Sequoia and Kings
Canyon National Parks into the 21st
century by starting the parks’ first invasive
plant management program. Our 865,964
acres are 97% wilderness, and we’re
fortunate that large extents of the parks
Athena carrying plants for restoration.
are relatively free of nonnative plants, so
we focus on prevention and early detection. Our control work targets invasive
perennial grasses (reed canarygrass and
velvet grass) in meadows, a highly-valued
ecosystem. Although these species are
challenging to control—reed canarygrass
builds a dense thatch layer that excludes
native plant recolonization—they are
of limited distribution in the parks and
eradication may be possible. Wearing my
“disturbed lands restoration” hat, I’ve also
planned and implemented the removal
of nearly 300 buildings plus roads and
parking lots from the parks’ premier giant
sequoia grove, Giant Forest, and the
restoration of a deeply eroded wetland,
8
Cal-IPC News Summer 2016
Halstead Meadow, crossed by the parks’
main highway. I feel fortunate to live and
work in such a large, biologically diverse,
and intact landscape. A personal goal is
to insure that yellow starthistle remains
excluded during my tenure here!
Sarah Minnick, Stewardship
Coordinator, Marin County Parks
[Pictured on cover.]
is part of a multi-year partnership with
The Nature Conservancy that allows us
to devote additional resources toward
coordination, prioritization, and monitoring, all of which are important in protecting rare species and their habitat at Ring
Mountain.
Jim Dempsey, Environmental
Scientist, California State Parks
I am the natural resources manager
for the Northern Buttes District, which
includes 15 park units in nine inland
counties north of Sacramento. I grew up
in Chico and 16 years ago returned to
live here, a town that is very lucky to have
the awesome Bidwell Park (a 3,670 acre
wildland city park). I was talking with my
89-year-old dad recently about Spanish
broom spreading down the watershed
into the park, and we reminisced about
treasured family memories of spring wild
flower displays with rich scents of nectar,
now largely disappeared due to exotic
grasses. Today, intrepid hikers venturing
into the upper reaches of Bidwell Park
can still catch remnants of those historic
treasures, while they last. Sometimes we
need someone with clear memories over a
generational time span to remind us what
has been lost, and what more may be lost.
It’s easy to lose track in our everyday rush.
What will the next generation bring? I
work to stop weeds wherever I can, and
encourage everyone to get out there and
enjoy our wildlands today!
As the Ring Mountain Stewardship
Coordinator, I protect and restore serpentine grasslands that are home to numerous
native and rare species, one of which (the
Tiburon mariposa lily) grows nowhere else
in the world. It may be a small
preserve in a sea of residential
development, but it holds great
importance for preserving the
region’s sensitive biodiversity.
With many edges, neighbors,
visitors, and trails, weeds come
in from all directions. I focus
my efforts on those that are able
to infiltrate harsh serpentine
soils, such as thistles in the
genus Centaurea and French
broom with its ability to alter
soil nutrients and eliminate
grassland habitat. I am always
keeping an early detection eye
out for new threats like barbed
goatgrass. I engage the local community of residents, schools,
and businesses in volunteer
work as a way to share the
importance of this preserve
and encourage participation
in its stewardship. It takes
the coordinated efforts of
volunteers, contractors,
and staff work groups
to keep the worst weeds
under control. Thanks to
such efforts, we eradicated
yellow starthistle from the
preserve in 2007, and we
continue to control pampas
grass. Marin County Parks
Jim with a group of Boy Scouts.
Native soil bacteria as biocontrol
By Travis Bean, UC Riverside and Elise Gornish, UC Davis, bean@ucr.edu
B
iological control of invasive plants
can have many advantages over more
conventional management methods,
namely the potential for regional scale
control of target species over the long
term if the control agent can be effectively
established. It also avoids the often-unpopular use of herbicides and the habitat
disturbances involved with mechanical
and physical control. However, because
biological control often relies on moving
the control agent from one region to another, it can require extensive research to
ensure there is neglible risk of unwanted
impacts on non-target native or desirable
organisms. In the best case, the control
agent would be native to the region, just
not present in sufficient numbers to cause
the desired effect on the target invader.
This is an actual scenario that
may yield a novel tool for managing
invasive Eurasian winter annual grasses
in the western United States, thanks to
USDA-ARS researchers in Oregon and
Washington. They have recently publicized the results of a long-term field trial
investigating the utility of native soil bacteria for selective control of the cheatgrass
(Bromus tectorum, a.k.a. downy brome),
jointed goatgrass (Aegilops cylindrica),
and medusahead (Taeniatherum caputmedusae), while not adversely impacting
native plant species.
Research into this promising management tool started in the 1980s in
eastern Washington when Pseudomonas (a
common genus of soil bacteria native to
much of the western U.S. and elsewhere)
was found on the roots of stunted winter
wheat and associated with a reduction
in tiller number in affected plants.
Recognizing that many of the Eurasian
winter annual grasses which are ecosystem
transformers in the western U.S. are close
relatives of wheat, researchers wondered
if the bacteria might also negatively affect
these invaders and offer a potential management tool to mitigate their negative
Cheatgrass invades pinyon/juniper/sagebrush country in the intermountain west,
changing the vegetation community by altering the wildfire regime. BLM photo from
the Salt Lake Tribune.
effects on biodiversity and productivity
of range and croplands. To investigate
this possibility, researchers have screened
over 20,000 potential bacterial candidates
through greenhouse experiments and field
trials over the last 20 years located around
the inland Pacific Northwest for selective
control of cheatgrass, medusahead, and
jointed goatgrass.
Recently, they made a breakthrough
with Pseudomonas fluorescens strain
ACK55. By using ACK55 similarly to a
pre-emergent herbicide, researchers found
that at a rate of one pint of active culture
(1 x 108 colony forming units mL-1) per
acre, sprayed in the fall prior to emergence
of the target invasive plant species, P.
fluorescens ACK55 is extremely effective at
controlling cheatgrass, jointed goatgrass,
and medusahead by inhibiting root cell
elongation and tiller initiation. In fact, a
single application appears to be adequate
for almost eliminating these annual weeds
from the seed bank in the long-term (4-5
years). This is about the normal lifespan
of P. fluorescens in the soil.
Other positive results that would
increase its utility in an Integrated Pest
Management (IPM) program for Eurasian
winter annual grasses include tests of over
200 non-target plants demonstrating that
the bacteria do not affect crop or native
species, meaning that P. fluorescens can
provide selective control of the target
invaders. In the presence of P. fluorescens,
crops and natives are able to competitively dominate the suppressed weeds and
increase in cover. Research has also found
that P. fluorescens does not inhibit fish,
birds, bees, and other insects. Moreover,
since the strain has no known antifungal or anti-bacterial activity, it is not
expected to disturb the native microbial
communities.
As is the case with pre-emergent herbicides, which this biological control agent
most resembles in terms of application
protocols, researchers have stressed that
several other factors, such as soil properties, temperatures, and precipitation, can
…continued page 14
Cal-IPC News Summer 2016
9
New pest-disease complex threatens California forests
By Shannon Lynch, Akif Eskalen, Gregory S. Gilbert, UC Riverside and UC Santa Cruz. shannon.lynch@ucr.edu
T
ogether with the avocado industry,
land managers of native forest
communities in southern California face
the imminent threat of a new emergent
pest-disease complex: Fusarium dieback
– Shot Hole Borers (FD-SHB). Our
work points to a path forward to make
informed decisions on best approaches to
management.
The beetle gallery in an infected tree.
Controlling emergent pests in the
critical early stages of invasions is generally difficult because costly management
decisions must be made with insufficient
data. Which areas are most vulnerable to
an infestation? How do invaders spread
across a landscape? What management
options are most effective?
A Complex Management Problem
The dieback is caused by the combined effects of two ambrosia beetles (the
polyphagous and Kuroshio shot hole
borers; PSHB, KSHB, both Euwallacea
spp.) and the specific fungal pathogens
each beetle carries (Fusarium euwallaceae
and Fusarium sp.)
In 2003, a single PSHB beetle was
caught in a California Department of
Food and Agriculture trap in Long Beach.
The beetle went unnoticed until 2012
when it was found damaging backyard
avocado and urban forest trees in the
Los Angeles basin. A rapid monitoring
response uncovered the broad host range
of the pest-disease complex, but its ability
to establish in native vegetation was only
gradually recognized.
Since 2012, these pests from Southeast
Asia have killed or caused dieback of
41 tree species on which the beetles can
reproduce, including 17 California natives
(see sidebar, page 12). Another 262 species in 64 families are attacked but do not
support beetle reproduction. However,
they provide a substrate from which the
beetle may find reproductive hosts.
This broad host range makes native
After the beetles leave, the Fusarium
fungal pathogens continue to colonize the
wood.
Cal-IPC News Summer 2016
riparian, oak woodland, and mixed
evergreen communities highly susceptible
to invasion and mortality by FD-SHB
(Eskalen et al., 2013). By October 2015,
FD-SHB infested over 280,000 native
trees in the Tijuana River Valley in San
Diego County, including arroyo willow
(Salix lasiolepis), Goodding’s black willow
(S. gooddingii), and mule fat (Baccharis
salicifolia) (see figure, pg. 13, Boland
2016). We continue to confirm FD-SHB
attacking native vegetation in many new
areas throughout San Diego, Los Angeles,
Orange, and Riverside Counties (Eskalen
and Lynch pers. obs.).
These particular plant communities
are critical breeding habitat for endangered species such as the least bell’s vireo
(Vireo bellii pusillus), southwestern willow flycatcher (Epidomax traillii extimus)
and arroyo toad (Anaxyrus californicus).
As FD-SHB kills willows, cottonwood,
and mule fat, it can make riparian
habitats more susceptible to invasion by
giant reed (Arundo donax) and saltcedar
(Tamarix spp).
Decision-making is further entangled when invaders spread across
multiple land-use jurisdictions. Such
uncertainty can cause delays and inefficient and ineffective use of resources.
Our research team has developed an
approach to reducing this uncertainty to
confront FD-SHB with both short- and
long-term control solutions.
10
Ambrosia beetles, also known as shothole borers, interact with fungus to cause
dieback of trees. Photo by Shannon Lynch
At these early stages of the epidemic,
preventative and containment measures
can fortunately still be effective, providing adequate, rapid assessment of key
landscape factors.
…continued page 12
WMAs, who needs ‘em? The low desert, for one
By Lynn C. Sweet, UC Riverside, lynn.sweet@ucr.edu
R
ecently, representatives from state,
federal, tribal and county agencies as
well as local organizations came together
in a small room in Palm Desert. The
goal: to resurrect the Low Desert Weed
Management Area (LDWMA), which
covers parts of Riverside and San Diego
counties containing the Colorado and
Mojave Deserts. The process was jumpstarted by members of the community who felt a vacuum in the wake
of a Natural Resource Conservation
Service-funded coordination program
that had brought together partners
and stakeholders for several years to
work on invasive plant problems, but
had flagged after the funding cuts
to the California Dept. of Food and
Agriculture’s WMA program.
as in the case of Sahara mustard (Brassica
tournefortii), which was brought in as a
contaminant from northern Africa with
date palm operations.
In the low desert, focus has been
directed in recent years to areas where
invasive plants threaten federally endangered species, such as the Coachella Valley
fringe-toed lizard, an endemic species
For years, WMAs in California
benefited from funding for priority
on-the-ground weed control projects
as well as the much-needed coordination process itself (meetings, project
planning, platforms for sharing data).
After the cuts, only some WMAs
have continued to meet, buoyed by
An Urban Conservation Corps crew works on
in-kind donations of time, tools and tamarisk in Palm Canyon. Photo by Jennifer Prado,
dedicated intentions to coordinate
Friends of the Desert Mountains
invasive plant management on the
ground.
that UC Riverside researchers found to
be negatively impacted by Sahara musResurrecting an organization is not
tard. In addition to research on how to
easy, and some soul-searching has been
utilize phenology and chemical controls,
part of the process for the LDWMA.
efforts to control Sahara mustard have
The group is diverse. Desert systems in
been primarily the domain of organizaCalifornia (and elsewhere) harbor many
tions such as the Friends of the Desert
rare and endemic species, as well as suites
Mountains, who mobilize volunteer forces
of species in ecosystems found nowhere
to pull weeds, with some notable successes
else. While not as ecologically producin priority areas.
tive as coastal or northern systems, the
Colorado Desert has its share of invasive
species, plants that can make quick work
of open areas during the short winter
rainy season or within the riparian and
seasonally-wet corridors that snake
through the canyons and valleys. Many
invaders are native to other arid regions,
from which they were imported for windbreaks (such as Tamarix species) or were
brought in accidently with agriculture,
The question for the LDWMA and
other WMAs is how to coordinate efforts
without the push of funding. Members
of the LDWMA are discussing these
among other questions to target the best
directions, aims and goals of a WMA in
the sans-funding era. Without having
the “carrot” of funding for on-the-ground
efforts, what are the concrete benefits of a
WMA? How can we best take advantage
of Cal-IPC’s existing resources? What
are the prospects for restoring funding to
WMA programs?
Though the ability of the group to
initiate projects will be limited by the
current lack of seed grants, the LDWMA
believes it can nonetheless provide useful
coordination in many areas, including:
invasive species mapping and monitoring; control project coordination;
volunteer mobilization; and
information-sharing on environmental review issues. Led by the staff
from the Coachella Valley Resource
Conservation District and an ad-hoc
committee, many of the members of
the LDWMA are also involved with
monitoring and management through
the Coachella Valley Multiple Species
Habitat Conservation Program,
which provides a strong foundation
and existing network of diverse
skillsets and experience among the
stakeholders.
Also, knowing that Cal-IPC has
stepped into a role as regional facilitator across the state, helping WMAs
set priorities and pursue funding,
gives us a sense that there is some
outside support for this effort. A few
other regions have successfully secured
grants for weed management projects
from state restoration programs funded by
bond measures, and as we move forward
we may investigate the potential for a
similar effort in our region.
Finally, we hold out hope that at
the state level, funding will be restored
because a small ongoing budget for local
weed management coordination is an excellent investment in protecting the state’s
environment. It would certainly provide
the basic funding for this essential early
detection network and pay dividends for
sensitive species, water supply, agriculture,
fire safety and a host of other important
issues. The LDWMA currently meets
quarterly in Palm Desert, CA. To join,
contact lynn.sweet@ucr.edu.
Cal-IPC News Summer 2016
11
…Pest-disease from page 12
Current practices in avocado groves
and urban forests rely on control measures
such as systemic pesticides that are not
generally appropriate for use in native
habitats. Similarly, chipping infested
wood to a size smaller than 1 inch, followed by solarization, kills the beetles, but
it is not possible to cull trees that provide
nesting habitat for endangered bird
species.
An integrated pest management (IPM)
program for native vegetation includes
(1) developing tools to quickly detect new
infestations and identify the beetles and
fungi; (2) identifying which habitats are
most vulnerable to FD-SHB and are most
important in its spread; and (3) evaluating preventive and curative biological,
mechanical, and chemical control options
appropriate for different habitat types.
Early detection and rapid identification are critical. With two beetle species
and at least two fungal pathogens involved
in this pest-disease complex (Lynch et
al. 2016), molecular tools to quickly and
accurately identify the beetles and fungi
are being developed to tailor control
measures to the appropriate pest-disease
complex (Stouthamer unpublished).
Rapid identification tools are also essential
for accurate mapping of the distribution
of FD-SHB. But impacts and site-specific
risk cannot be determined based only on
where the beetles have already arrived.
Risk Assessment of Habitats
Effective management of an emergent
pest-diseases complex requires predicting
where it will spread and cause damage. We
have begun a systematic survey throughout regional urban-wildland forests and
agricultural lands, and are measuring
vegetation and landscape characteristics,
microclimate, and resident beneficial
microorganisms across sites.
By combining these survey data
with what we know about host range
into an adaptive risk model, we can
interpolate likely areas of spread into an
interactive map tool to aid managers with
decision-making.
12
Cal-IPC News Summer 2016
Such early detection surveys and
site-specific risk assessments help decisionmakers focus resources in the face of
insufficient data, and have reduced costs
of management of invasive ambrosia
beetles by 39% compared with no surveillance (Epanchin-Niell et al. 2014). This
adaptive model, continuously improved
with new survey data and field testing,
will help prioritize management efforts to
specific sites and avoid unfruitful efforts
in low priority sites.
Controls in Development
Native trees and shrubs affected:
Box elder (Acer negundo)
California sycamore
(Platanus racemosa)
Red willow (Salix laevigata)
Black willow (Salix nigra)
Arroyo willow (Salix lasiopeis)
Cottonwood (Populus fremontii)
Black cottonwood
(Populus trichocarpa)
Two approaches are being studied to
effectively control FD-SHD. The first
approach uses pesticides. Several systemic
pesticides identified in preliminary field
experiments show promise for controlling
the beetles and fungi on individual trees
if applied prior to infestation (Eskalen
et al. unpublished data). Our landscapebased risk assessment will help reduce the
environmental impacts of such pesticides
by targeting their use as they continue to
be tested and developed.
Engelmann oak
(Quercus engelmannii)
The second approach uses endophytes
for biological control. Endophytic fungi
and bacteria live inside plant tissues, and
are analogous to the gut microorganisms
that play a role in our own immune
systems. We have already isolated several endophytes from local avocado and
sycamore trees that escaped disease, and
found they reduced the growth of the
Fusarium pathogens. Our preliminary
results additionally show that Fusarium
spp. cannot colonize young avocado and
sycamore plants inoculated with beneficial
endophytes.
Mesquite (Prosopis velutina)
We are currently working with land
managers to collect endophytes from
additional surveyed native trees and
test their biocontrol potential. We are
conducting experimental trials to test
if these protective endophytes can be
inoculated prophylactically into seedlings
and saplings of native plants to facilitate
restoration of habitats and improve
landscaping even where FD-SHB has
become established.
Our risk model will be used to evaluate locations where resident endophytes
may reduce vulnerability and where
endophyte treatments may be most useful.
Valley oak (Quercus lobata)
Palo verde (Parkinsonia aculeata)
Mule fat (Baccharis salicifolia)
Big leaf maple (Acer macrophyllum)
Coast live oak (Quercus agrifolia)
White Alder (Alnus rhombifolia)
Blue palo verde (Parkinsonia florida)
Goodding’s black willow
(Salix gooddingii)
Summary
Appropriate management protocols for
FD-SHB are contingent on a number of
different landscape factors. Understanding
these factors is time-sensitive and will result in long-term cost savings. Landscape
assessments are urgently needed to
provide managers with the information
they need to prioritize use of limited
funds. Individual stakeholder agencies can
play a critical role by helping us document current impacts to better inform
an integrated landscape risk model of the
spread of FD-SHB. For updates and more
information, visit www.eskalenlab.ucr.edu
and www.pshb.org.
Literature Cited
Boland J.M. 2016. The devastating impact of
an invasive ambrosia beetle on the riparian habitats of the Tijuana River Valley, California. PeerJ
Preprints 4:e1964v1https://doi.org/10.7287/
peerj.preprints.1964v1
Epanchin-Niell, R.S., Brockerhoff, E.G.,
Kean, J.M., & Turner, J.A. 2014. Designing
Severe dieback in native vegetation due to FD-SHB over the course of one year in the Tijuana River Valley.
cost-efficient surveillance for early detection and
control of multiple biological invaders. Ecological
Applications 25(6): 1258-1274.
dieback and its ambrosia beetle (Coleoptera:
Scolytinae) vector in southern California. Plant
Disease 97(7):938-951.
Eskalen A., Stouthamer R., Lynch S.C.,
Rugman-Jones P.F., Twizeyimana M., Gonzalez
A., Thibault T. 2013. Host range of Fusarium
Lynch S.C. et al. 2016. Identification,
pathogenicity and abundance of Paracremonium
pembeum sp. nov. and Graphium euwallaceae sp.
nov.- two newly discovered mycangial associates of the polyphagous shot hole borer
(Euwallacea sp.) in California. Mycologia. DOI:
10.3852/15-063.
Cal-IPC News Summer 2016
13
…Soil bacteria from page 9
mediate treatment effectiveness, specifically noting that the bacteria may not
perform as well under hot and arid conditions experienced in summer months. As
with all invasive plant management and
restoration methods, timing is critical;
along with cooler temperatures, precipitation is required within two weeks of
application for the bacteria to effectively
colonize the soil. This means that successful application relies heavily on seasonal
precipitation and a lack of unseasonably
warm fall weather, which may be more
limiting in future years under some
climate change scenarios.
P. fluorescens ACK55 is currently
undergoing the EPA registration process,
which can take about 17 months. If
accepted by EPA, the inoculate could be
available for widespread use. In California,
pathogens intended for controlling weeds
require authorization from the California
Department of Pesticide Regulation,
and other states may have similar
requirements.
Other than state-specific restrictions
on using pathogens for invasive plant
control, there are also the hurdles of
propagation: what is the cost of growing
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Cal-IPC News Summer 2016
enough of the bacteria to supply it to
farmers, ranchers and conservationists
interested in using it to control invasive
winter annual grasses in the western U.S.?
Because it’s likely to be cost-prohibitive to
apply the bacteria to all of the millions of
acres currently infested by these problem
species, the researchers suggest that a
more targeted approach be considered.
One approach would be direct application of the bacteria to leading edges of
existing infestations to quarantine existing
populations and prevent spread into new
areas. Other priority targets are firebreaks
to control wildfire spread and recently
burned areas where the existing population of invasive grasses is restricted to the
seed bank, allowing the bacteria to have
the largest impact.
Additionally, site-specific factors may
limit effectiveness of the bacteria for
invasive grass control. As we often hear
restoration ecologists and practitioners
emphasize, control tools are most effective
when used as part of an IPM program,
rather than as a stand-alone treatment. In
fact, as the researchers themselves suggest,
the bacteria is unlikely to be successful if
simply applied to invasive grass monocultures, as the grasses will simply regenerate
given sufficient time. Instead, researchers
suggest that post-emergent herbicides be
applied to reduce the standing crop of
invaders, while also applying the bacteria
to attack germinating seedlings and
provide seed bank control over the longer
term. Seeding or planting natives or desirable forage species can help reestablish a
diverse and resilient plant community that
can resist or prevent recolonization by
invasive grasses.
For more information:
Ibekwe, A.M. et al. 2010. An assessment of
environmental conditions for control of downy
brome by Pseudomonas fluorescens D7. www.ars.
usda.gov/SP2UserFiles/Place/20360500/pdf_pubs/
P2098.pdf
Kennedy, A. et al. Microbial control of
cheatgrass, jointed goatgrass and medusahead
(presentation). www.fwaa.org/accounts/fwaa/
data_documents/60/files/10b-dl-2011-1213_130p_kennedy,ann.pdf
Kennedy, A. et al. Cheatgrass suppressive
bacteria research (factsheet). http://sfc.smallfarmcentral.com/dynamic_content/uploadfiles/152/
biocontrols%202.pdf
Dickie, G. 2015. Researchers find an answer
to invasive cheatgrass. High Country News, www.
hcn.org/articles/researchers-find-formidable-foe-forinvasive-cheatgrass
Solomon, C. 2015. Researcher finds way
to fight cheatgrass, a western scourge New York
Times, www.nytimes.com/2015/10/06/science/
researcher-finds-way-to-fight-cheatgrass-a-westernscourge.html
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The WILDLAND WEED CALENDAR
UC Davis Weed Day
July 7, UC Davis
wric.ucdavis.edu
Natural Areas Conference
October 21-22, Davis
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July 17-20, Madison, WI
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November 14-17, Sacramento
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May 9-11, 2017, Savannah, GA
www.invasivespecies2017.org
“ Researchers have been desperately looking for a way to overthrow cheatgrass’s reign for decades,
and have tried some wacky experiments in the process — from fungal pathogens like the macabre Black
Fingers of Death to changing soil texture to introducing super absorbent polymers into the ground to
soak up water. Now, after nearly 30 years of trials and research, Ann Kennedy has found the innocuous
cure — native soil bacteria.”
~ From “Researchers find an answer to invasive cheatgrass”. Gloria Dickie, High Country News,
Oct. 16, 2015, www.hcn.org/articles/researchers-find-formidable-foe-for-invasive-cheatgrass