cal eppc news€¦ · mule power. britt schumacher of the tehama county agriculture department,...

Protecting California’s Natural Areas from Wildland Weeds

Inside:Weed warning fromdownunder!Not just in the garden anymore:Oxalis pes-capraeWal-Mart dumps pampas grassTeaching teachers about weeds

Yes, Calla lilies. In Western Australia, which has a Mediterranean climatesimilar to ours, Zantedeschia aethiopica is commonly known as arum lily.It is also known as an aggressive invader of forests and forested wetlands.This photo was taken mid-September (late winter) by John Randall ofThe Nature Conservancy’s Wildland Invasive Species Program about 135km south of Perth near the Tuart Forest National Park. What lessons inprediction might we learn from invasives in other Mediterraneanclimates? Our lead article from two Australian researchers addresses thisimportant issue.

Cal EPPC NewsVol. 11, No. 1, Spring 2003 Quarterly newsletter of the California Exotic Pest Plant Council

From the Director’s Desk

Quick, what time of year do the rains come?For most people in the world, the answer would be, “Summer!” But for most Califor-nians, the answer is, “Winter, of course.” Our “Mediterranean” climatic regime of hotsummer drought and winter rain is found over only 2% of the world’s landmass.Besides California and the Mediterranean Sea area itself, three other regions have asimilar climate: Chile, the tip of South Africa, and western and southern Australia.

Because wildland weeds are often climate dependent, many of our invasives come fromthese other Mediterrean climate regions—eucalyptus from Australia, brooms from theMediterranean, Cape ivy from South Africa, and Spartina densiflora from Chile, forinstance. Likewise, California natives can misbehave in other Mediterranean regions—California poppies and Monterey pine, for instance, are invasive in Chile, Europe,Australia and New Zealand. Of course we import weeds from other climatic regions,and export to them as well, but there is a special ecological link between the world’sMediterranean climate zones when it comes to invasive exotics.

What are the implications of this? For one, plants that have proven themselves to beinvasive in one of these regions should be considered potentially suspect in the otherregions. In hopes of thwarting further invasions, such information can put us a stepahead for potential invasives not yet established in one of these regions. Our coverarticle addresses this very issue. The Australian authors examine how several of theirweeds (which are sold in nurseries here) might fare in California wildlands by using aclimatic model that assesses where a particular plant may be able to naturalize.

The link between Mediterranean climate zones also means that we need to worktogether. The Australian article demonstrates one way in which we can join forces topredict potential invasives before they get started. There are other effective ways tocollaborate. The International Broom Initiative’s efforts to develop biocontrols for afamily of brooms and gorse is a great example. By coordinating research among all areasinfested with broom—including California, Oregon, Washington, British Columbia,Hawaii, New Zealand and Australia—and by working on Scotch, French, Spanish,Portuguese and other invasive brooms together, the project is designed to accomplishmuch more than could any one country working on any one plant. We need all theefficiency we can get.

2 CalEPPC News Spring 2003

CaliforniaExotic Pest Plant

Council

1442-A Walnut Street, #462Berkeley, CA 94709

(510) 525-1502www.caleppc.org

A California 501(c)3 nonprofit organization

Our MissionCalEPPC works to protectCalifornia’s natural areas

from wildland weeds throughresearch, restoration, and education.

Executive Director

Doug [email protected]

Board of Directors

Joe DiTomaso (President)UC Davis Weed Science Program

Steve Schoenig (Vice President)California Dept. of Food & Agriculture

Mona Robison (Secretary)UC Davis Weed Science Program

Becky Waegell (Treasurer)The Nature Conservancy

Mike Kelly (Past President)Friends of Penasquitos

Carla BossardSt. Mary’s College

Matt BrooksUSGS Western Ecological Resource Center

Deanne DiPietroSudden Oak Death Research Project

Tom DudleyUC Berkeley Dept. of Integrative Biology

Dawn LawsonUS Navy Facilities

Carri PiroskoCalifornia Dept. of Food & Agriculture

Alison StantonBMP Ecosciences

Scott SteinmausCal Poly San Luis Obispo

Peter WarnerCalifornia State Parks

Bill WinansSan Diego County Watershed Management

CalEPPC NewsSpring 2003 - Volume 11, Number 1

Editor: Doug Johnson, [email protected]

CalEPPC News is published quarterly by the CaliforniaExotic Pest Plant Council. Articles may be reprinted

with permission from the editor. Submissions arewelcome. We reserve the right to edit all work.

From www.themediterraneangarden.org/climate/map.cfm

CalEPPC News Spring 2003 3

Wildland Weed NewsNewsNewsNewsNewsThe Center for Invasive Plant Manage-ment (CIPM) in Montana has awardedgrants to three WMAs in California—Butte County for water-milfoil control,Yolo County for mapping sloughs androadside revegetation, and Lake countyfor outreach and education. Onlineapplications for this year at<www.weedcenter.or g>.

Members of the International BroomInitiative presented the project at aUSDA-sponsored forum at their Albanylab January 17. IBI is again working withCalifornia's congressional delegation tosubmit a funding request for the lab toresearch biocontrols for brooms and gorse.Project partners from Oregon, Washing-ton, Hawaii, British Columbia, Australiaand New Zealand advocating for the $1.4million request point to the high ecologi-cal and economic costs of expanding

broom infestations and the need for acost-effective strategy that address theseinfestations on a landscape scale.<www.caleppc.org>

Funding for CDFA weed programs hasbeen cut severely in the governor'sproposed 2003/04 budget. Whencombined with December's cuts, thislatest cut chops the program by 50%,severely reducing staff and operatingexpenses in the Biocontrols and Weed &Vertebrate programs. This cut will havelong-lasting impact on our ability tocontrol weeds in the state, and CalEPPC,with partner organizations through theCalifornia Invasive Weed AwarenessCoalition, is campaigning to have thesecuts reversed. Your voice can help in thismatter. To express your concerns, seesample letter and information at<www.caleppc.org>.

Congressman Hefley (R-CO) and SenatorCraig (R-ID) have reintroduced theHarmful Invasive Weed Control Act,which seeks $100 million a year until2006 for local weed management groupsnationwide.

CalFlora, the much-used online botanicaldatabase, closed shop February 1 due toinsufficient funding. Staff and volunteerscontinue to pursue sources of stablefunding, with the goal of reopening assoon as possible. Visit <www.calflora.org>for more information.

Mule power. Britt Schumacher of the Tehama County Agriculture Department, ridingCharlie Horse, takes Brittany the mule into dry creek beds to spray arundo andtamarisk. This spring he plans to use her for a small brush control project in steepcountry that’s difficult to access. Britt got the trained mule from a successful weedprogram in Idaho.

Board ChangesThe CalEPPC Board of Directorswelcomes two new members—CarriPirosko of Redding and DeanneDiPietro of Petaluma. Carri coordi-nates weed outreach in northerncounties for the California Depart-ment of Food & Agriculture, and iskeenly interested in education.Deanne works with the Sudden OakDeath Research Project at SonomaState. She has also been involved withTeam Arundo del Norte, and wasinstrumental in developing the state’sweed mapping handbook released lastSeptember. Their experience andenergy will be a great addition to theboard!

At the same time, we extend ourgratitude to outgoing directors CarlBell of UC Cooperative Extension inSan Diego and Paul Caron ofCalTrans in Ventura for their dedi-cated work on the board over the lasttwo years. This was Carl's second tourof duty, and we greatly appreciated theexperience and insight he brought toour strategic planning. Thanks!

Save the date!

CalEPPC SymposiumOctober 2-4, 2003

North TahoeConference Center

Reprinted from the proceedings of the13th Australian Weeds Conference, heldSept. 8-13, 2002, Perth, Western Australia.H. Spafford Jacob, J. Dodd, J.H. Moore, eds.Council of Australian Weed Science Societies

The authors propose that any plantboth: (a) native to one Mediterraneanclimate region, and (b) a known weed inat least one other, should automatically beviewed as a threat to other Mediterraneanclimate regions where it has not yetnaturalised, or has only a limited distribu-tion.

The focus of this paper is on speciesnative to South Africa that are weedy inthe southwest of Western Australia(Hussey et al. 1997) and available in thehorticultural trade in California. Thespecies selected are three geophytes—bridal creeper (Asparagus asparagoides (L.)W. Wight, Asparagaceae), watsonia(Watsonia meriana (L.) Mill., Iridaceae),and arum lily (Zantedeschia aethiopica (L.)Spreng., Araceae)—and the small treetaylorina or blue scurf pea (Psoraleapinnata L., Fabaceae). Two Australianspecies, bluebell creeper (Sollyaheterophylla Lindl., Pittosporaceae) andVictorian tea tree (Leptospermumlaevigatum (Gaertner) F.Muell.,Myrtaceae), are also discussed briefly.

METHODSThe native and naturalised distribu-

tion data for the three geophytes andtaylorina in both South Africa andsouthwest Western Australia weredetermined and analysed, with CLIMATEpredicting back to the world dataset todetermine just how much of Californiawould be suitable for establishment.

Weed warning from downunderThe weed potential of selected South African plantsin cultivation in CaliforniaBy Roderick P. Randal1 and Sandra G. (Sandy) LloydDepartment of Agriculture, Western Australia, andCooperative Research Centre for Australian Weed Management

Feature


CLIMATE is a predictive applicationthat uses long term meteorological stationdata from within the known range of aplant to determine similar climates withinAustralia. Originally developed by theWestern Australian Department ofAgriculture, and based in part onBIOCLIM (Nix 1986), this software canalso be used to analyse back to the largeglobal meteorological station data of9,460 weather stations. In countrieswhere station coverage is very high, suchas the USA, good predictions can beobtained.

CLIMATE uses 16 climatic variables,all derived from long-term monthlytemperature and rainfall data. The outputparameters in the prediction maps(Figures 1-4) equate to 0-30% variancefrom ideal climate (black squares) to 30-50% variance from ideal climate (opencircles) based on the ideal native andnaturalised climate mean. The blacksquares represent those areas most at riskof the analysed species establishing andbecoming problematic.

The naturalised range in WesternAustralia (WA Herbarium 1998) wasincluded in each analysis to increase theefficacy of the predictions. In many casesa species can survive climatic conditionsoverseas outside those it inhabits in itsnative range, and a subsequent CLI-MATE analysis may predict a widercoverage than if the native range, alone,were used. This ability to adapt to ortolerate a range of climates is a commoncharacteristic of many weed species.

RESULTSAll four species analysed by CLI-

MATE showed good climate matches for

significant areas of California, fromSonoma County south to San DiegoCounty. There were also a few locationsfurther north in Washington state wherepopulations of these species may establish,although the cooler winters may limittheir spread and impact.

Bridal creeper is found along thesouth coast of South Africa and northeastthrough the Drakensberg into theTransvaal (Kleinjan and Edwards 1999). Itwas introduced to Australia in the mid-1800s and earned its common namethrough its widespread use in bridalbouquets and floral arrangements.Populations increased dramatically in thelate 20th century to the point where itwas named as a Weed Of NationalSignificance (WONS) in 1997 (Anon2001). Bridal creeper occurs fromDongara to Esperance in WesternAustralia, as well as other areas acrosssouthern Australia, and has been recordedas naturalising in California near SanDiego, Los Angeles and San Francisco(CalFlora 2002). The CLIMATE predic-tion (Figure 1) shows that large areas ofthe Sacramento and San Joaquin Valleysaround Los Angeles, San Louis Obispoand San Diego are climatically suitable forestablishment of bridal creeper.

In South Africa, taylorina occurs alongthe coast from the Western Cape provinceinland to Lesotho and north to theTransvaal and is commonly found aroundwetlands or soaks (Palgrave 1996).Introduced to Western Australia as asource of honey, taylorina has naturalisedextensively along the wetter south coastalfringes from Albany and Denmark toMargaret River and moist areas aroundPerth.


Taylorina is not yet known to benaturalised in California; however, plantsare available from at least once source inSan Francisco (Potrero Gardens 2002).The CLIMATE prediction (Figure 2)shows large areas of the SacramentoValley, Los Angeles and San Diego to beclimatically suitable for its establishment.

Watsonia is distributed along thesouthwest Capes of southern Africa(Goldblatt 1989) and was common incultivation in Australia prior to beingrecognised as a 'garden thug' (Randall2001).

Watsonia has naturalised throughmuch of the southwest of WesternAustralia, as well as other areas acrosssouthern Australia. Already wellnaturalised in Mendocino and Sonomacounties in California (CalFlora 2002)watsonia is recognised as an invasivespecies in the County of Mendocino townplanning regulations (County ofMendocino 2002). The CLIMATEprediction (Figure 3) shows large areas ofthe San Joaquin Valley and around SanDiego and Los Angeles to he climaticallysuitable for establishment.

Arum lily, also known as calla lily, is awidely used ornamental around the world.Its distribution in South Africa stretchesalong the coast from the Western Capeprovince, inland to Lesotho and north tothe Transvaal (Scott 1997). It is extremelyinvasive in Western Australian wetlandsand irrigated pastures, particularly in theBusselton-Margaret River area, and is alsonaturalised in other southern States ofAustralia. Arum lily has already beennoted naturalising around old homesteadsand seeps in Sonoma, Monterey andSanta Clara counties (CalFlora 2002 andRandall pers. comm. 2002). The CLI-MATE prediction (Figure 4) shows thatlarge areas of the Sacramento and SanJoaquin Valleys, Los Angeles, San LouisObispo and San Diego are climaticallysuitable for establishment.

DISCUSSIONMany countries are looking at risk

assessment to identify and prioritise weedthreats for a range of reasons, including:

increased knowledge about the threatof invasive plants to natural ecosystems;

knowledge of the 'sleeper weed'

concept (i.e. the long lag phase betweenintroduction and impact);

trends towards an holistic biosecurityapproach rather than just quarantine foragriculture;

the adoption of quarantine policiesthat are based on formalised weed riskassessment rather than simple prohibitedspecies lists; and

increased pressure from communitiesexpecting more from quarantine systems.

Some of these assessment processes aretime consuming and costly, and it is oftendifficult to obtain data on particularspecies.

Many scientists consider that manyparts of the world are entering an'homogocene' era, or a 'Mc-Donaldisation' of the world's species.That is, the replacement of regionaldiversity by homogenous ecosystems,characterised by cohorts of invasivespecies that are the same worldwide. TheMediterranean climate regions are noexception and, because of their mildclimate and high human populations, arelikely to be the worst affected regions.There is no shortage of examples ofMediterranean species that have made animpact around the world, including theubiquitous charlock (Sinapis arvensis L.),which is found on every continent and isa weed of crops in over 50 countries(Holm et al. 1997) and common privet(Ligustrum vulgare L.) which was afavoured garden plant for centuries and isnow a major environmental weed onseveral continents.

The Mediterranean climate ischaracterised by having cool, wet wintersand warm to hot, dry summers. Regionssharing this climate are the southwest ofWestern Australia, parts of South Austra-lia, southwestern California, southwesternAfrica, parts of Chile and the Mediterra-nean basin itself.

Examples of Australian native specieswith demonstrated weedy behaviour inAustralia that clearly indicate potentialinvasiveness in similar climates overseas,are bluebell creeper and Victorian tea tree.

Bluebell creeper, a popular gardenplant native to southwest WesternAustralia, has become an environmentalweed in southeastern Australia, creatingdense clumps that grow over existing

Fig. 1bridal creeper

SF

SD

SF

SD

SF

SD

SF

SD

Fig. 2taylorina

Fig. 3watsonia(large arrow indicatesSonoma andMendocino counties)

Fig. 4arum lily


downunder......continued from preivous page

native vegetation (Blood 2001). It ispresent from Sonoma County to SanDiego County (Hickman 1993) inCalifornia, but is not yet known to haveestablished in South Africa.

Victorian tea tree, a native of south-eastern Australia, was used as an orna-mental, coastal dune stabiliser andwindbreak (Blood 2001). After beingintroduced to Western Australia, itquickly spread into coastal heath andwoodlands in the lower southwest,creating dense thickets. It is a declarednoxious weed in South Africa (Henderson2001) and is also present in California(CalFlora 2002).

Climate matching programs such asCLIMATE or CLIMEX (Sutherst andMaywald 1985) are useful tools forpredicting where such species mayestablish, but are not essential whengeneralising for major climatic types.Because of their demonstrated weedinessin Australia, both Australian speciesmentioned should be considered to havesignificant potential to establish in otherMediterranean climates.

It is worth noting that predictions forthree of the four species analysed show asmall area near Aberdeen in Washingtonstate (Figures 2-4) to be climatically

suited to allow growth. This is a reminderthat this type of analysis can only indicatethe gross areas of climatic suitability,whereas many smaller microclimates withtheir potentially unique vegetation mightnot be indicated as suitable.

The documentation of known invasiveplant species within identified climatetypes can be a fast and effective means toidentify potential new weeds in regionswith the same climate type.

REFERENCESAnon. (200 I ). Bridal creeper (Asparagus aspara-

goides) Strategic Plan. National Weeds strategyExecutive Committee, Launceston. URL: www.weeds.org.au/

Blood, K. (200 I). 'Environmental weeds: A fieldguide for SE Australia'. (C.H. Jerram andAssociates, Melbourne).

CalFlora: (2002). Information on California plants foreducation, research and conservation. Berkeley,California: The CalFlora Database. URL:www.calflora.org/ (Accessed: March-April 2002)

County of Mendocino (2002). Gualala Town PlanChapter 6 -Appendices, B. Landscape SpeciesLists. Invasive species: Not recommended for usein landscaping plans. (March 2002) URL:www.co.mendocino.ca.uslplanning/GTP/gtpchap6.pdf

Goldblatt, P. ( 1989). 'The genus Watsonia'. (NationalBotanic Gardens, South Africa).

Henderson, L. (2001 ). Alien weeds and invasiveplants. Plant Protection Research Institute andAgricultural Research Council, South Africa.

Hickman, J.C. (Ed.) (1993). 'The Jepson manual.Higher plants of California. 5th edition'. (Uni-versity ofCalifornia Press California, USA).

Holm, L.G., Doll, J., Holm: E.,' Pancho, J. V. andHerberger, J.P. ( 1997). 'World weeds. Natural

histories and distribution'. (John Wiley and SonsNew York, USA).

Hussey, B.M,J., Keighery, G., Cousens, R.D., Dodd,J. and Lloyd, S.G. ( 1997). 'Western weeds, aguide to the weeds of Western Australia'. (ThePlant Protection Society ofWA. Inc.)

Kleinjan, C.A. and Edwards, P.B. ( 1999). Areappraisal of the identification and distributionof Asparagus asparagoides in southern Africa. S.African J. Bot. 65, 23-31.

Nix, N.H. ( 1986). A biogeographic analysis ofAustralian elapid snakes. In' Atlas of Australianelapid snakes', ed. R. Longmore, pp. 4-15.(Bureau of Flora and Fauna, Canberra).

Palgrave, K.C. (1996). 'Trees of Southern Africa'.(Struik Publishers, Cape Town, South Africa).

Potrero Gardens (2002). Rare and unusua/ p/ants,San Francisco (Accessed: March 2002). URL:www.potrerogardens.com/autumn2001.htm

Randall, J.M. (2002). Personal cornrnunication. TheNature Conservancy, Wildland Invasive SpeciesTeam, California.

Randall, R.P. (2001). Garden thugs, a national list ofinvasive and potentially invasive garden plants.Plant Protection Quarterlv 16(4),138-171.

Scott, J.K. ( 1997). The distribution of arum lily andits invasive potential. Proceedings of a workshopon arum lily (Zantedeschia aethiopica) eds J.K.Scott, and B.J. Wykes, 7 August 1997, GardenIsland, Western Australia. CRC for WeedManagement Systems, Adelaide, pp. 10-16.

Sutherst, R. W. and Maywald, G.F. ( 1985). Acomputerized system for matching climates inecology. Agriculture, Ecosystems and Environ-ment 13, 281-99.

Western Australian Herbarium ( 1998). FloraBase-Information on the Western Australian flora.(Accessed March-April, 2002). Department ofConservation and Land Management. URL:www. calm. wa.gov.aulscience/florabase.html.

Arum lily in a woodland. Photo by John Randall, taken in Australia’s LeeuwinNaturaliste National Park. The majority of trees in the oversory are Agonisflexuosa, commonly known as peppermint or willow myrtle (Myrtaceae).

The California Weed Science Society ispublishing a comprehensive identificationmanual for aquatic and riparian weedswest of the Rocky Mountains, with 560color photos of 170 species of submerged,floating leaf, and emergent aquatic weeds.$5 discount for pre-publication orders!<www.cwss.org/aquatic_book.htm>


Species Focus

Oxalis pes-capraeBy Jake Sigg

If one needs an illustration of thefunction of natural controls on anorganism, they need look no further thanyellow oxalis (aka sour grass or Capesorrel, Oxalis pes-caprae), a scourge of theCalifornia coast. It is a rare and endan-gered plant in its home range of SouthAfrica, where native fowl eat the foliage, a

mammal digs the bulbs, and parasitesinfest bulbs. Freed from these energy-suckers in California, its spread near thecoast is untrammeled.

The purpose of this article is (a) toelicit help in determining how yellowoxalis disperses, (b) to heighten awarenessof its surreptitious spread, and (c) tosuggest removal techniques and potentialproblems with those techniques.

People are incredulous when learningthat viable seed from this plant has neverbeen reported in California. Afterabsorbing this information, their exasper-ated question follows: but HOW does itget around? Oxalis’ abundant productionof bulb offsets and lateral runners partiallyaccounts for it but doesn't fully explain itsalarming spread—how it travels so fast,how it gets across the road, or onehundred yards up the hill, or into asecond-floor flowerbox. Contaminatedsoil may account for some occurrences

like the window-box, but that can'texplain all the populations, especially inwildlands.

The latest version of the CalEPPCweed lists published in 1999 dodged thequestion of how to rate yellow oxalis,treating it as “needing more information.”Up to then it had been considered a weedof disturbed areas (a relative term—isthere any part of low-elevation Californiathat is not disturbed?). At this time oxalisbegan rising on my personal worry listand in the last three years I have becomepanic-stricken as I see it proliferatingacross landscapes. In heavy soils itmultiplies rapidly; in sand it explodes. Ina remnant native plant communityoccupying a stabilized sand dune near myhouse in western San Francisco, Iwatched a small semi-circular infestationwith an approximate radius of twenty feetspread seemingly exponentially inapproximately fifteen years to dominatethe whole ten-acre natural area, which isnow on its way to becoming a monocul-ture. I wasn't watching its progress thatclosely because I was too busy with otherconcerns, but it surely did not spreadentirely by lateral runners. It must haveleap-frogged, but lacking time-lapsephotos, that will never be known. Now itmay not be possible to save the site'sbiological community.

I don't know how or when it came toCalifornia. Bailey's 1930 The StandardCyclopedia of Horticulture listed it (as O.cernua), so it was probably in the horti-cultural trade then. It is not listed in thewild in the 1925 Jepson Manual. Thefirst mention of it as a weed known to mewas the 1951 Robbins, Bellue, and BallWeeds of California as O. cernua. Theyreported it in orchards in the SanFrancisco Bay Area and southern Califor-nia. It may have been more widespreadthan that, and it may have been incultivated sites before 1925. It has beenin the Mediterranean area since the 18thcentury and it doesn't produce seed thereeither.

It certainly does like disturbance. (Onan amusing side note, a weed brochureproduced in the Bay Area recommendedgetting rid of oxalis by rototilling, a sure-fire way of quadrupling its numbersovernight! Please, please—don't throw me

in that briar patch!) However, it no longerrequires active soil disturbance toestablish, and it is an increasinglyaggressive invader of native plant commu-nities. Once established in a grassland,dune, or even shrubland, its advance isinexorable and without human interven-tion the outcome is inevitable. Althoughit is active only during the brief rainyseason, when days are short and the sun islow in the sky, populations neverthelessrapidly expand, displacing plants that arephotosynthetically-active year-round.Free of the need to produce extra energyto support wildlife (nothing eats it), therobust photosynthetic engine pumps outenormous quantities of energy to pro-

duce—in about February or earlyMarch—prodigious bulb offsets andlateral runners to invade surroundingareas and to muscle out even plants muchlarger than it.

A lateral runner travels several inchesat a time; it is a peculiar fat, translucentorgan resembling an icicle, with emergentslender, white, one-inch shoots at the tip(see illustration next page). It inserts itself

© Br. Alfred Brousseau, Saint Mary's College

continued next page...

from Robbins, Bellue, and Ball,Weeds of California, 1951, p272


continued from previous page...

into the middle of an already crowdedclump of healthy natives, even into thetight center of a vigorous bunchgrass orrush, where it steadily burgeons, captur-ing space and light. Its roots competewith the bunchgrass and even with nativeshrubs such as coffeeberry or coyote bush.Whether this direct competition canweaken or eventually kill a shrub is notestablished, but it is certain that it willprevent a new generation of that or anyother plant at the site.

Thus, long-term prognosis is for amonoculture of oxalis. No matter whichcommunity is invaded, year-by-year theoxalis becomes stronger and the otherplants become weaker. It evenoutcompetes many aggressive weeds,although it meets a worthy rival in thesame habitats preferred by its fellowSouth African, Ehrharta erecta (seeCalEPPC News Summer/Fall 1996). Itwill be interesting to see which of thesetwo bullies predominates on a given site;ehrharta is the only plant I know that canprevent oxalis from becoming a monocul-ture. (I am excepting another SouthAfrican, Cape ivy (Delairea odorata),which in a favorable moist or shady sitewill smother both oxalis and ehrharta.)

Eradication is difficult and time-consuming because of that bulb. Remov-ing a small infestation in a discrete area isa feasible project. I was able to manuallyrid it from my garden, which containedmany hundreds of oxalis plants, bypersisting in removal of the above-bulbparts for four or five years. Repeatedtimely removal of top-growth will deprivethe bulb of its stored energy. Optimumtime for this is winter or early spring justbefore it starts producing offsets. Placingfingers at soil level beneath the crown andpulling gently but steadily (two handsbetter) will frequently get the wholetaproot, especially when growing in sand.The bulb will probably remain and stillhave some stored energy to produce moretop-growth. A repetition of the precedingoperation during the same season willeither kill the plant or draw down itsenergy so severely that one more pullusually effects kill, providing it is well-timed and does not allow time for the

bulb to recharge its energy. There is needfor monitoring for an additional two yearsto make certain, as I have sometimesfound a single small leaf hiding amongother plants, slowly building up its bulb'sstrength for a comeback.

For large tracts spraying may be the

only option, although a judgment callmay arise if the oxalis is so intermixedwith the natives that killing it may entailkilling the natives. Some people reasonthat they are going to lose the communityanyway, and eradicating the weed willallow them to re-establish the natives. Idon't know of definitive information onthe effectiveness of herbicides on oxalisbulbs. Anecdotal information I receivedsays that 2% glyphosate is effectiveproviding you have a good surfactant,since oxalis leaves tend to shed water. Ihave not verified this information. Afurther consideration is if the infestationis in grasslands with few or no nativedicots present, triclopyr may be a betterchoice, as it is designed to kill dicots butnot monocots.

I hope this article will elicit interest inthis pernicious weed and perhaps generatea satisfactory explanation for its spread. Iborrowed an idea from scientist JoeBalciunas, who offered a $100 reward foranyone finding fertile seed of Cape ivy inCalifornia for his biocontrol researchproject. It worked for Cape ivy—viableseed was found and Joe is $100 poorer. Idecided to make an identical offer toanyone who produced viable seed or averifiable seedling of yellow oxalis, and Ipublished the offer in a recent issue of theCNPS Yerba Buena Chapter newsletter.Greatly to my surprise, botanist Lee Ellisprovided me color photocopies ofseedlings with cotyledon leaves from herEast Bay garden. This is very importantinformation and I encouraged her todeposit herbarium specimens in the

Jepson Herbarium and with CDFA.However, I do not think this answers

the question about the plant's means ofdispersal, as I have checked innumerablepopulations without finding viable seed oryoung plants with cotyledon leaves. Untilproven otherwise, I will assume that seedproduction is an uncommon occurrence,and this accords with the information inthe Jepson Manual. If it is not uncom-mon, that would be vitally importantinformation. So the mystery is still there.As Lee graciously declined the reward, Iwill re-offer the $100 to the first partyproducing proof.

Jake Sigg is Invasives Chair for the Califor-nia Native Plant Society. He can be reachedat <[email protected]>.

Mom’s tipsMy daughter shared her formula for

oxalis removal with me. Weed by handearly in the season and often. The plantputs out tiny nutlets near the crown asthe weather warms, in addition to theflowers, and the idea is to get it out ofthe ground before the nutlets and/orflowers (and the next generation) have achance to form.

I have pulled all the plants in an areaonly to go back a few days later to findnew ones. However, the new plantsappear to be smaller each time I return.In some areas it’s stopped coming back.

She also suggested Roundup, butthat did not work for me, I thinkbecause it is too cool here in theRussian River watershed. The instruc-tions say it needs to be 60 degrees towork, and by the time it’s that warm thenutlets and flowers will have formed.

One thing I find interesting is theplant’s structure. It has a long root thatforms a 1" nut about ten inches belowground. Later in the season when I siftthrough the soil I find these nuts belowthe surface, sometimes attached to aswollen white root like matter. That,plus the scattered nutlets that spreadout when the plant is disturbed—nowonder oxalis is so difficult to eradicate!

Victoria Wikle


New and Contributing Members

Sustaining Members:Doug Allshouse (Friends of San Bruno Mountain, Daly City) · GregArchbald (Santa Barbara) · Gladys Baird (Encinitas) · Carolyn Johnson& Rick Theis (Sebastapol) · Fred Kramer (San Diego) · William McCoy(Berkeley) · Connie Rutherford (Ventura)

Contributing Members:Martha Blane (Martha Blane & Associates, San Marcos) · MarianChambers (Central Sierra Partnership Against Weeds, Sonora) · SarahChaney (Channel Islands National Park, Ventura) · Darlene Chirman(Chirman Biological Consulting, Santa Barbara) · Tom Dodson (TomDodson & Associates, San Bernardino) · Doug Elliott (US ForestService, Miwuk Village) · Lawrence Janeway (Chico) · Jo Kitz(Mountains Restoration Trust, Woodland Hills) · Ralph Kraetsch(Walnut Creek Open Space Foundation, Walnut Creek) · JenniferLangford (Jenesis Ecological Services, Avila Beach) · Mark Langner(Bridgeport) · Susan Cochrane Levitsky (Cameron Park) · Tamia Marg(Claremont Canyon Conservancy, Berkeley) · T. Charles Moore(Sunnyvale) · Mike Peters (Fallbrook Land Conservancy, Fallbrook) ·Susan Schwartz (Friends of Five Creeks, Berkeley) · Peter Slattery (MossLanding Marine Lab, Salinas) · Stephen Underwood (California StateParks, McKinleyville) · · Clarence Weinmann (Berkeley) · DoloresWelty (Encinitas) · Linda Willis (Soquel)

New Members:Clay Courtwright (Stone Lakes National Wildlife Refuge, Elk Grove) ·Mark Frey (Presidio Trust, San Francisco) · Yvette Redler (USDA APHISPPQ, Sacramento) · Jim Sharp (Berkeley) · Christopher Thayer (SycamoreAssociates, Walnut Creek) · Marilyn Walter (Portola Valley Ranch Land-scape Committee, Portola Valley)

Thank you for your prompt renewals. We aplogize if we forgot you or got your information wrong! Please let us know by emailing<[email protected]>. All personal information is kept confidential.

Gift Memberships:Rosemary Gunn (Walnut Creek; gift from Mark Renz) · Adeline Gunnerson(Walnut Creek; gift from Mark Renz) · Diane Nygaard (Preserve Calavera,Carlsbad; gift from Ynez Yoder) · Mr. & Mrs. Doug Whiting (Carlsbad; giftfrom Ynez Yoder) · Mr. & Mrs. Thomas Lyon (Oceanside; gift from YnezYoder) · Bob Isaackson (Allan Hancock College, Lompoc; gift from CharlesBlair) · Nathan Hulse-Stephens (Davis; from Geri Hulse-Stephens)

Family Members:Margaret Graham & Walter Earle (Mostly Natives Nursery, Tomales Bay) ·Wilma & William Follette (Sausalito) · Franklin & Jean Olmstead (FoothillsPark, Palo Alto) · Don Stiver (CNPS, El Cerrito) · Michael & Jerre White(Conservation Biology Institute, Encinitas)

Institutional Renewals:Thomas Reid Associates (Palo Alto) · Jesse and Jason Giessow (Dendra, Inc.,Encinitas) · Buford Crites (City of Palm Desert) · Ron Unger (EDAW,Sacramento) · Cache Creek Conservancy (Woodland) · Mike Biscieglia(DeAngelo Brothers, Inc., Chino) · Jean Ferreira (Elkhorn Native PlantNursery, Moss Landing) · Patricia Oliver (Ventura County ResourceConservation District, Somis) · John Anderson (Hedgerow Farms, Winters) ·David Gilpin (Pacific Coast Seed, Livermore) · Huntington Library (SanMarino) · Dave Moore (San Mateo County Parks, Redwood City) · City ofSan Diego Park Rangers · California State Parks, Santa Cruz District ·Helen Crocker Russell Library, Strybing Arboretum (San Francisco) · SmallWilderness Area Preservation, Inc. (Los Osos) · Sue Gardner (Golden GateNational Parks Association, San Francisco) · Steven Ash/IPM-PCAAssociates (San Rafael) · David Sands (Go Native Nursery, LLC, Montara) ·Sue Weis (Inyo National Forest, Bishop)

Sometimes we change our minds. A Boy Scout plantingpampas grass for the Soil Conservation Service in Los AngelesCounty, 1953. [From a California Resource ConservationFund card. Thanks to Carla Koop for submitting the photo.]

Oxalis invades north coast dunesAndrea Pickart of the Humboldt Bay National Wildlife Refuge in

northern California reports that O. pes-caprae has within the past twoyears started to spread explosively into native dune habitats. It is nowencroaching upon endangered plant areas maintained by the Bureau ofLand Management and by the City of Eureka. She also reports that O.pes-caprae is extremely aggressive, and that it the only plant that hasbeen observed surviving and coexisting with iceplant (Carpobrotusedulis), another prolific invasive exotic species of coastal dune habitats.Pickart adds that O. pes-caprae often forms dense mats in any area withopen space, and that is very successful at competing with and excludingnative plants. Even when it does not exclude natives, it has detrimentalimpacts in open unvegetated areas, as it causes soil enrichment andstabilization of semi-stable areas, altering ecosystem nutrient cycling.

[Info from The Nature Conservancy’s Wildland Invasive Species Team’swebsite. Visit http://tncweeds.ucdavis.edu/alert/alrtoxal.html for moreinformation on oxalis.]


[CalEPPC awarded a mini-grant to the K-12 Alliance in 2002.]

CalEPPC made a significant contribu-tion to the training of California scienceteachers this past summer. Using invasiveplant models and issues to learn about lifescience concepts, twenty teachers, grades5-12, became field researchers conductingexperiments and collecting and recordingdata over a two-week period.

The K-12 Alliance is a school sciencereform project in California. Teachersparticipate in a two-week institute in thesummer, featuring science inquiry and

content sessions, and have follow-upworkshops during the school year. The K-12 Alliance convenes institutes inSacramento, San Diego and the LA/RIMS area (Los Angeles, Riverside, Inyo,Mono, San Bernardino).

The LA/RIMS summer institute washeld at Diamond Ranch High School inDiamond Bar, California, July 28 throughAugust 9. The teaching cadre consisted ofthree teachers: Lorrae Fuentes, Directorof Education at Rancho Santa AnaBotanic Garden; Keith Thompson,Science Curriculum Coordinator andformer high school science teacher,Fontana Unified School District; and IanSigner, Environmental Educator andCurriculum Specialist at the CaliforniaInstitute for Biodiversity. We planned

lessons and activities throughout thewinter and spring, and decided early toteach biology concepts around the centraltheme of invasive species of plants.

We also wanted to provide resourcesfor teachers to get their students involvedin "action field projects" like weedmapping, weed removal and habitatrestoration. Towards this end, we planneda one-day field trip to Catalina Island aspart of the two-week institute. There areextensive threats to native plant species byinvasives on the island, but the CatalinaIsland Conservancy has an aggressiveresearch and restoration program. Theyalso have a comprehensive educationaloutreach program.

CalEPPC, CNPS, and the Center forInvasive Plant Management all contrib-uted curriculum and print resources aswell as funds for getting teachers toCatalina for a day of exploration. Thanksto these organizations, twenty teachersand their hundreds of students are farmore aware of invasive plants, and havemore understanding of the impacts on thenative plant communities of California.

Contact Lorrae at<[email protected]>

EDUCATION & OUTREACH

Inquiry in action: Using invasiveplants for teacher trainingBy Lorrae Fuentes

Readings &Resources

FANCY CARWASHPortable Agricultural Soil Wash

An outfit from Platina has developed avehicle washing unit that can be leased toclean fire-fighting vehicles on site. Washwater can be drained on site or contained,and pads absorb petroleum. Six spraynozzles rinse vehicles’ undersides, and twopressure washers allow you to washwheels, etc. Service includes a 3,000-gallon water tender and two operators.Info: Eddie Pokorny at 530/628-5669.

TEACHING BIODIVERSITYCal Alive!

California Institute for Biodiversity<www.calalive.org>Cal Alive! is an interactive CD-ROM setcovering California's biological diversityfor grades 4-8. Experiments, stories,games, fly-bys, and virtual field trips bringthe state's 53 different habitats to theclassroom, promoting interactive learningabout the state’s climate, geology, ecologyand heritage. Classroom guides andteacher resource guides are included.

SPECIAL SECTIONJournal of Conservation Biology

<conbio.net>The February issue of ConservationBiology has a six-paper special section onthe "Population Biology of InvasiveSpecies" from authors including CalEPPCmember Ingrid Parker of UC Santa Cruz.


The WILDLAND WEED CALENDAR

“The International Union for theConservation of Nature estimates that since 1600, 109species of mammals, birds, reptiles, amphibians, fishes,invertebrates, and vascular plants have become extinct inwhat is now the continental United States… at least4,500 nonindigenous species have established free-livingpopulations in the United States over the past fewhundred years… On balance, this part of the world hasseen an increase in biological diversity.

Allan Fitzsimmons, newly appointed wildlands fuel coordi-nator for the Department of the Interior, from a Fall 2000issue of Markets and Morality as reported in Sierra, Jan/Feb2003).

Quotable:

“With international trade at unpre-cedeted volumes, the worldwide reshuffling of organismsis now a major driver of global change. We live in a timethe ecologist Gordon Orians dubbed "The Homogocene"to describe how once unique places have come to re-semble each other—with massive environmental andeconomic impacts.

Phyllis Windle, Union of Concerned Scientists,"Connectingthe dots: Bringing the invasive species issue into focus," Fall2002, Catalyst (semiannual magazine of UCS) 1(2):14.

””

National Invasive Weed Awareness Week

February 24-28Washington, DC4th annual gathering of weed managersto participate in visible public activitiesand to lobby their representatives.<www.nawma.org>

2003 Western Society of Weed ScienceAnnual Meeting

March 11-13, 2003Koloa, HI<www.wsweedscience.or g>

Third International Conference onMarine Bioinvasions

March 16-19, 2003Scripps Institution of Oceanography,La Jolla, CA

Sponsored by the California Sea GrantCollege System and The MIT Sea GrantCollege Program.<www.sgmeet.com/mb/>

California Weed Awareness Week

July 6-12A week to plan local weed tours, newspa-per articles and other outreach events. Forideas from WMAs that sponsored eventslast year, contact Nancy Brownfield at<[email protected]> or Wendy Westat <[email protected]>.

Save the date!

CalEPPC Symposium 2003

October 2-4North Tahoe Conference Center

Wal-Mart stopsselling pampasgrass in CaliforniaLetter from Carolyn Martus

[CalEPPC member Carolyn Martus ofCarlsbad got frustrated when she sawpampas grass for sale at WalMart, and wrotethem an email. It was forwarded toWalMart's west coast buyer, who decided totake pampas grass off the master list ofplants available to stores! Carolyn alsoconvinced an REI store to remove pampasgrass from their landscaping. She has nowturned her attention to other big box outletswhere the plant is sold.]

I've received lots of kudos andcongratulations for getting WalMart totake pampas grass off their shelves, but Ihave to admit that it was pretty easy anduncontroversial. It took all of about 15minutes to pull up their website, go totheir customer service section andcompose a few sentences. I wrote them avery short email, one paragraph long, andincluded a link to Carrie Schneider'sproposal to the City of San Diego to banpampas grass.

Briefly, I told WalMart that pampasgrass is wreaking havoc in our open spacesand if they want to help the environment,they need to take it off their shelves. My

email was concise and positive. I con-gratulated them for giving back to thecommunity and stressed how we neededto work together to help the environ-ment. I believe most people and busi-nesses will do the right thing once theyknow they are causing harm to a commu-nity or environment.

Until CalEPPC can convince CDFAto list Cortaderia selloana as a noxiousweed, it will be up to individuals toeducate others. Make it your New Year's

resolution to talk to one neighbor or localbusiness about pampas grass, and get someeducational materials to help your case.

For an excellent brochure to use whentalking to people about pampas grass, visit<http://wric.ucdavis.edu/information/pampasgrass.html>. Carolyn can be reachedat [email protected]. To express supportfor Linda Prendergast's decision to removepampas grass from WalMart shelves, writeher at 3233 Grand Ave., Suite N-411,Chino Hills, CA 91709-1489.

Honk If You PullWildland Weeds

CalEPPC Membership FormWe’re working to protect California’s wildlands from invasive plants—join us!CalEPPC’s effectiveness comes from a strong membership, including scientists, land managers, policy makers, and concerned citizens.Please photocopy the form below, complete, and mail with your payment. Additional donations are always welcome to support ourprojects; we are a 501(c)3 nonprofit organization, and donations beyond regular membership rates are tax deductible.

1442-A Walnut Street, #462Berkeley, CA 94709

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Please mail check (to “Cal-EPPC”) and this form to:Cal-EPPC Membership1442-A Walnut Street #462Berkeley CA 94709

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Got a good idea for a bumper sticker?Contact Jon Fox at <[email protected]>

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