First Hand Experiences in Managing Different ... - Weeds Australia

Asparagus plumosus is thepriority weed being managedwithin Iluka Nature ReserveBitou bush (above) and many otherweeds are being managed as part ofa holistic management programA plan was developed by NPWS and the IlukaLandcare Group which allocated resources andresponsibilities. As envisaged, the majority of thefunds were for a bush regeneration contract whichfocused on the arduous and technically demandingjob of controlling the A. plumosus infestations inthe reserve and the multi-species infestations on thereserve margins fronting the urban areas.Due to the existing and potential impact of A.plumosus, it was targeted as the major priority forcontract work. The approach was for all treatmentareas to receive an initial and two follow-uptreatments with specific targets to be met. Thepurpose was to undertake as thorough a treatmentas possible to reduce the threat to the rainforest andbush and minimise follow-up.The method adopted was to initially cut the vinesat head height, which were climbing into thecanopy, and to recut the vines at ground leveland then spray the regrowth. This initial treatmentwas extremely time consuming. Vines were cutover a 3–4 month period commencing in winter1997 and then sprayed the following autumnwinterwhen regrowth was 10–15 cm high. A 1:50glyphosate:water mixture with the additive Li-700 ®was used to minimise off-target damage and thevolume of herbicide used. Many plants were alsocrowned, hand removed and hung to dry.Follow-up monitoring and controlAfter two years, the asparagus infestations wereless than 5% of their original densities andregeneration of rainforest seedlings was abundant.Follow-up occurred annually over the next 5 yearsAsparagus plumosus vines were cut at head height, then at groundlevel, and regrowth sprayedand concentrated where the densest infestationsoriginally existed. Plants missed previously andnewly emerged seedlings were targeted.Over the last 8 years, work has continued asneeded at intervals of 1–4 years. Small amountsof new asparagus seedlings or juvenile plantshave been treated, often by Iluka Landcare Groupmembers. Other features of the project includedtraining the community group in bush regenerationtechniques, creating awareness and support inthe local and broader community and involvingvolunteer groups to support the Iluka LandcareGroup’s work on multiple sites.SuccessAsparagus plumosus infestations are less than 1%of original infestation levels in the Iluka NatureReserve. The program has expanded to treat weedinfestations on nearby public land, in cooperationwith Clarence Valley Council, and a successfulpilot program was run to provide free weedcontrol for private residences. This project is partof a wider landscape restoration project spanning800 ha of heavily weed-infested area that includesIluka Nature Reserve, Bundjalung National Parkand public lands managed by Clarence ValleyCouncil. Restoration has now been implementedover approximately 80% of the 800 ha projectarea by all three levels of government, IlukaLandcare Group, and other volunteers. A longterm,systematic and persistent effort is essential toachieving restoration aims.94

Grubbing became the preferred method for controlling matureWestern Cape bridal creeperareas are also sometimes infested with gorse orblackberry, prickly weeds that create difficultconditions for the detailed searching required.Approach to managementTrials were undertaken early to identify the bestcontrol approach. Grubbing was selected tocontrol mature plants, as it was a far more effectivethan spraying. While plants were suppressed andprevented from fruiting the following season,the herbicide did not kill these plants andthey eventually re-established. Seedlings weresuccessfully controlled using glyphosate (450 g/kg)at a rate of 1:100 water, plus wetting agent.The initial cost for grubbing is expensive but it isfar more efficient in the longer term. Masses ofseedlings germinate after removal of mature tubersand these are spot sprayed. This combination ofgrubbing mature plants and spot spraying seedlingsis a more targeted approach that reduces the risk ofoff-target damage to native lilies and orchids, whichare active at the same time of year as the controlprogram. To further manage this risk, specialisedbushcare contractors are engaged.Natural Resources AMLR works closely with theCity of Tea Tree Gully and Adelaide Hills Councils.Many volunteer groups, such as the Friends ofAnstey Hill and North East Hills EnvironmentalConservation Association, also contributesignificantly to control in public areas. The AMLRNRM Board successfully secured funding via theAustralian Government Caring for our Countryinitiative for Natural Resources AMLR staff toimplement this high priority program. These fundsOne of many dense infestations of Western Cape bridal creepergrowing in the AMLR region, prior to controlwere used to employ specialised contractors toconduct on-ground works. Public awarenessactivities are also part of the program and are veryimportant for private landholders.‘It is vital to have community input and support anda committee has been formed to facilitate this.’Key challenges and successesOccasional new outlying plants are still beinglocated, but these are usually single plants ratherthan established sites.In this region, Western Cape bridal creeperthreatens an area of 1400 ha and over 150 privateproperties. Natural Resources AMLR surveys thearea annually and controls all plants. Due to theeradication status of this weed, and the importanceof finding and removing every plant, these servicesare offered to landowners free of charge. Liaisonwith landowners to gain access and carry out ongroundworks is intensive.In 2007, 15 tonnes of tubers were grubbed fromthe area and disposed of by deep burial. In 2011and 2012, close to two tonnes of tubers wereremoved, as the thickest, densest and easiest to findinfestations were removed early in the program.‘Remaining plants are now harder to find andmuch more on-ground searching is involved,especially in the more difficult to access terrain.’The program is clearly getting closer to eradicatingWestern Cape bridal creeper from the AMLR region,but a continued, long-term effort must be sustained.96

! Asparagus declinatus^! Asparagus asparagoidesCase study siteNo Reported Occurrencerequires detailed understanding of plant life cycles,soil types and climatic conditions.In the Adelaide Hills and Fleurieu Peninsularegions, many native annuals such as orchids, liliesand ferns withdraw into their rootstock for a periodof summer dormancy with the onset of hotter, drierconditions in mid to late spring. The asparagusweeds, with their larger tuber and rhizome systems,persist a few weeks longer on the surface. Duringthis time they can be sprayed without impacting thedormant native plants.Spraying with a strong solution at this stage oftheir cycle has proven particularly effective, asthe herbicide is drawn down into the rootstock.However, younger seedlings fade earlier in theseason and are likely to be missed. It is importantto revisit the site during the same window ofopportunity the following year to manage seedlings.‘If the project runs for three to four years, you’vegot a good chance of picking up all the weeds.’Refining the techniqueKnapsack foliar spraying using metsulfuron-methylat 5–7 g per 100 L is the preferred application.A surfactant is added, which makes the herbicidego further and helps penetrate the waxy asparagusfoliage. Fine spray nozzles are used on the veryfine foliage of A. declinatus which enables theoperator to apply small hits onto little patches andavoid overspray. Dye is used to keep careful trackof applications.‘Metsulfuron-methyl is very effective on A.declinatus and A. asparagoides. Glyphosate willwork but it is less selective and can do a lot of offtargetdamage.’Instead, glyphosate is used to treat watsonia(Watsonia meriana var. bulbillifera) and Africancornflag (Chasmanthe floribunda (Salisb.) N.E.Br.)using similar principles to those for asparagusweeds.Reading the sites – timing is keyThere is a lot of variation from site to site, soeach must be assessed individually and itsconditions understood. During the brief window ofopportunity, usually in October to early November,the work is intensive. As rainfall and temperaturevary from year to year, so does the timing. Thismakes it difficult to forward plan and covermultiple, dispersed sites. For example, plants willdry off earlier at sites with a northerly aspect or onexposed heights and will linger longer at sites witha southerly aspect or in sheltered valleys where it iscooler and wetter.Soil type and weather conditions affect how longmetsulfuron-methyl has a residual activity in thesoil. When to control must be carefully plannedaround predicted weather conditions to limitdamage to off-target plants. Typically, there is atwo-week dry spell after spring rain events, givingsufficient time for the herbicide to become inert.98

Asparagus asparagoides before treatment in grey box grassywoodland, Belair National Park, Mount Lofty Ranges, SAAdditional time is needed in acid soils as thechemical is more persistent. Soils rich in organicmatter tie up the chemical and prevent it fromaffecting other plants.There is a high level of knowledge and expertiserequired to use metsulfuron-methyl effectivelyin bushland settings. Excessively high rates,heavy applications, wet conditions and limitedunderstanding of soil types and native ecology canlead to devastating off-target damage.Making bushcare everyone’s businessSAIF director, Kieran Brewer, sees bushcare projectsas an opportunity to share knowledge about nativeplants, ecology and weed management.‘You work with people who really know theirplants. Volunteers have got a strong connectionwith their conservation site, their heart’s in it,they’ve got intimate knowledge and they’re greatto work with.’A project running in the Mt Lofty Rangesdemonstrates that working closely with acommunity group can disseminate skills, buildlong-term capacity and manage fragile species.The Woodcutters Road Environmental ProtectionAssociation, formed to conserve natural heritagevalues across their adjoining properties, whichcontain some high-value bushland, managesthe project. A spectrum of weeds is presentincluding A. asparagoides. Weed control bycontractors is into its fourth year. Populations ofGrey box grassy woodland, Belair National Park, Mount Lofty Ranges,South Australianationally endangered pink-lipped spider-orchids(Caladenia behrii Schltdl.) and stiff white spiderorchids(Caladenia rigida R.S.Rogers) are carefullymanaged. An integral contribution is being madeby a community member who was mentored by aNRM Officer, received training and now monitorsthe progress of every single plant, recordingpopulation, flower count and seed set.Achieving successMaintaining focus on the core outcomes ofpreserving rare species and building the resilienceof native vegetation has been the key to successwith SAIF’s projects. Weed management isalways conducted within this context and controltechniques are carefully selected and timed to limitdamage to existing native vegetation.Over the course of weed management, sites arecarefully monitored and documented, usingmultiple photopoints, mapping, written reportseach season and site visits with clients to discussprogress. After sufficient time has passed to showweed control objectives have been met, a finalinspection with the client usually concludesthe sign-off process. Long-term monitoring andmaintenance is then continued by the client, oftenby a dedicated community group.‘Instead of weeds you see all the native plant coveryou’d ever want.’99

Case study 5Protecting a Ramsar-listedwetland from the impacts ofAsparagus africanusBrisbane City Council! Asparagus africanus^Case study siteNo Reported OccurrenceBrisbane City Council (BCC) has been controllingAsparagus africanus (climbing asparagus) for thepast 5 years within the Boondall Wetlands toprotect these valuable coastal wetlands from totalcanopy destruction. Having largely containedthe problem, they are now shifting their focusto reducing the volume of asparagus within theReserve.Faced with a suite of over 450 potential or presentweed species and an area of 8000 ha of naturalareas to manage, BCC must prioritise weedmanagement activities to specific weed species andareas. Asparagus africanus has most recently beendeclared a class C or widespread pest that is to becontrolled when within or adjacent to natural areasunder the Brisbane Invasive Species ManagementPlan 2013–2017.Asparagus africanus is recognised as a seriousthreat to ecosystem function within theBoondall Wetlands Reserve and is targeted moreaggressively as a result.The Boondall Wetlands lie at the edge of theMoreton Bay Ramsar Site, which is one ofAustralia’s largest Ramsar sites and is internationallyimportant to migratory shorebirds. The Wetlandsare extremely diverse, with over 1000 ha of tidalflats, mangroves, salt marshes, melaleuca swamps,casuarina forests, grasslands, open eucalypt forestsand woodlands. This diverse landscape supports ahuge variety of plants and animals, many of whichare rare and endangered.What is the problem?In the past, a range of weeds (most notablygroundsel bush – Baccharis halimifolia L.) havedisturbed the Wetlands and been managedthrough a species-led approach. During the mostrecent period of drought, A. africanus expandedrapidly, threatening the structure and integrityof the established canopy. By the time this wasrecognised, A. africanus had heavily infestedan estimated 100 ha of the reserve. Infestationsoccurred predominantly within the melaleucaswamps and casuarina forests, where entirecurtains of the weed were forming and creatingimpenetrable barriers. The weed was alsocolonising the neighbouring eucalypt woodlandareas at a rapid rate.‘The wetlands are extremely sensitive todisturbance and have limited access options.Control activities therefore needed to strike abalance between reducing weed species vigourand limiting disturbance.’This was never more evident than when BCCattempted to use large groups of workers, workingin lines, to manually remove asparagus crowns byhand in Boondall Wetlands. Though this chemicalfree approach was effective in suppressing weeds,there was an unfortunate unintended consequenceof damage being caused to regenerating and100

was considered to be very effective at killingA. africanus with little damage to other plants.Crowning involves either cutting and removingthe crown directly from the adjoining root systemor cutting into the crown and applying herbicide.Initially, fluroxypyr or glyphosate was used but,more recently, fluroxypyr has been abandonedas it was considered to be no more effective thanglyphosate for this purpose.5. Managing other invasive vinesIpomoea cairica (mile a minute) is the otherinvasive vine in these areas that requires aggressivemanagement. It is managed in the same way asA. africanus except that 2,4-D-based products areused as they are considered to be more effectivethan fluroxypyr-based chemicals.Follow-up monitoring: making the effortworthwhileUntil 2010, there were only anecdotal indicatorsof any real success. After this, new assessment andmonitoring practices were implemented. Withinthe reserves, the exact frequency and volumeof treatment to be undertaken varies. However,history indicates that a minimum of four individualinterventions per growing season are required toensure positive success. Since 2008, a clear trendtowards better recruitment of native plant speciesand a reduction in A. africanus density has beenobserved. Annual site evaluations are conductedto assess the overall increase or reduction inweed densities as well as other outcomes such asdisturbance created through treatment and weedhygiene management practices.After Asparagus africanus control it looks like the weed is gone, butfollow-up monitoring and control is now critical to ensure that it staysthat wayPhoto-monitoring is used at these locations, butwith limited success to date due to:• seasonal variation causing difficultydistinguishing between weeds and desirablevegetation in photos,• symptoms of recent herbicide damagedemonstrating short-term weed suppressionin photos that may not necessarily translate tolong-term management,• difficulty in observing species succession from alandscape photograph, and• pickets or other markers used to guide thephotographer back to the same location oftenbeing moved or stolen.To enhance monitoring efforts, steps are nowunderway to set up mounted time-lapse camerasand permanent transects.Brisbane City Council has also commenced aproactive weed survey program that employscontractors to assemble a complete inventory ofpriority weeds within core reserves to developa strategic framework for their management andprovide a baseline measurements. Boondall Reservewas a pilot site for this activity in 2011 and wasmonitored again in 2013. The 2013 survey indicatedthat, since 2011, there was a 20% reduction of A.africanus in most parts of the site and limited tono increase in infestations in adjoining areas. Theaim set by Brisbane City Council to contain andgradually reduce A. africanus within these areas isclearly being realised.102

In 2005, Asparagus aethiopicus dominated the Bangalay SandForest understoreyonly hand removal was to be undertaken for twomain reasons: spraying would lead to hectaresof dry, dead fronds that could be a fire hazardand removing the crowns would allow maximumnatural regeneration.Despite being more resource intensive, manualcontrol techniques were selected by preference, asthe group considered these methods would betterencourage native plant regeneration in the area.As a trial, they also chemically treated a small 20 ×10 m zone using metsulfuron-methyl. They foundthat this method was effective in controlling A.aethiopicus, but asparagus seedlings continued togerminate from the soil-stored seed bank and therewas little to no regeneration of native seedlings.The number and diversity of native seedlingsthat naturally regenerated over the next 5 yearswas substantially less in this area compared withwhere they had manually controlled the weed.It should be noted that spraying of the trial areawas undertaken in the middle of a prolongeddry period of 10 years, with lower than averagerainfall occurring. Although metsulfuron-methylhas been used successfully to control asparagusweeds in other environments, the fact that it causedsuch detrimental impacts here highlighted theimportance of conducting a small-scale trial underthese specific climatic and ecological conditions,before attempting to use it more broadly.‘There was almost no regeneration of endemics(where A. aethiopicus was sprayed) until thepresent very wet season, yet there was amazingnatural regeneration everywhere else in theWorking together, the volunteers and contractors removed manytruckloads of Asparagus aethiopicusimmediate vicinity.’ Wendy Fuller, NarrawalleeForeshore and Reserves Bushcare Group.Follow-up monitor and control for many yearsto comeFollowing primary control efforts, the groupcontinued to look for and manually removeany new seedlings over the next 2 to 5 years.This proved to be an exercise in patienceand perseverance, with seedlings continuallygerminating from the vast seed bank. For ease ofcontrol, they waited until the leaves had formedbefore removing the seedlings, since researchindicated that they would not set flower and fruitwithin the first 2 years. This meant they couldconcentrate on removing only larger seedlingsduring each sweep of the site, but checking toensure that no seedlings were allowed to flower.‘Trying to remove the smallest seedlings wastedtime and effort as more often than not thesmall fronds would break off and, with the highlikelihood that they would re-shoot, we’d have toreturn to remove them a season or two later. Weused our available time on the greatest threat.’Wendy Fuller, Narrawallee Foreshore and ReservesBushcare Group.To remove asparagus seedlings during thesesecondary control and maintenance stages, thegroup used a simple 3-pronged garden hand forkwith the outside prongs ground off, turning it intoa type of hook. They found it created minimal104

disturbance and made their work faster, easier andsafer than using a knife or folding saw. It is no goodfor removing large plants, however.Control efforts were conducted during a longperiod of drought, which may have influenced theeffectiveness of different control techniques and therate of native plant regeneration. Since the droughtbroke in 2011, the group has observed an increasein the number and diversity of native plant speciesthat have germinated.Although no formal before and after monitoringhas been conducted, members of the NarrawalleeBushcare Group have maintained a constantpresence on the site since they commencedcontrol, and have watched the site change overtime. Casual observations from the group indicatethat the percentage and abundance of groundcover species has increased on the dunes, withvarious species of terrestrial orchids being observedgerminating for the first time.Deal with other weed incursionsIn the same area, Pittosporum undulatum Vent.(sweet pittosporum) had become dominant in thelower and mid-storey, and appeared to be alteringthe diversity of the Bangalay Sand Forest. Althoughnative to Australia, P. undulatum is a semi-rainforestpioneer that may be responding to changes in soilmoisture and fire regimes.As a result of this, Shoalhaven City Councilprepared a Review of Environmental Factors (REF)into the possibility of undertaking a staged controlprogram of P. undulatum at Narrawallee. The REFBy 2012, the densest infestations of Asparagus aethiopicus have beenremoved and native plants are regenerating in the once degradedNarrawallee Beach Dunessuggested using a combination of controlled burns,manual control and cut paint or direct injectionusing neat glyphosate. They are also replanting10% of the eucalypts each year to augment naturalregeneration.Some secondary weed invasion, mainly from Liliumformosanum A.Wallace (Formosan lily), has alsooccurred where A. aethiopicus has been controlled.Narrawallee Foreshore and Reserves BushcareGroup are controlling this using a snip-drip methodwith neat glyphosate and it has taken 5 years toreach a point where L. formosanum infestationshave been significantly reduced to less than 20% ofthe original population.Enjoy the success, but keep a watchful eyeWithin 7 years, the group has achieved its initialaim of removing the densest infestations of A.aethiopicus, and is maintaining the effort bymonitoring the site annually to ensure that it doesnot re-establish again. Native plant regeneration isalready occurring in the once degraded parts of theforedune vegetation as well as the Bangalay SandForest Endangered Ecological Community. This willhelp build resilience against future invasion of thisor other weeds.‘Natural regeneration has surpassed all ourexpectations and we are also witnessing the returnof several species of ground orchid and smallbirds.’ Wendy Fuller, Narrawallee Foreshore andReserves Bushcare Group.105

Case study 7Managing emerging asparagus weeds on the mid-north coastof New South Wales – Asparagus virgatus andAsparagus falcatusPeter Michael, Port Macquarie-Hastings CouncilAsparagus falcatus (sicklethorn) and A. virgatus aretwo emerging asparagus weeds that are currentlybeing managed by Port Macquarie-HastingsCouncil. Whilst they are in low abundancerelative to other vines and scramblers, the Councilis working to ensure they remain ‘[two] lesstransforming vine weeds they have to worry about’.For A. falcatus, Council’s objective is to eradicatethe weed in all instances. It is in the early phaseof establishment (sparse, isolated infestations,largely not yet naturalised) and eradication of theseinfestations is feasible and desirable based on thepotential impact if left unmanaged. By comparison,A. virgatus is more widespread and more difficultto control than A. falcatus. Therefore, Council aimsinstead to protect priority areas from this weed (i.e.areas of high conservation value), and in so doing,target resources systematically (e.g. locate, map,control, monitor) to prevent further spread andgradually reduce local infestations.What is the problem?Asparagus falcatus displaces native vines andscramblers in a range of ecological communities,is tolerant of a wide range of site conditions (e.g.coastal wind, salt water near the root zone, fullsun to deep shade, variable substrata) and isspread by birds and other animals. It, therefore,has the potential to spread widely and invade arange of coastal environments, including cliffs andheadlands, littoral rainforest and wet sclerophyllforest. Infestations usually consist of an established‘parent’ plant (founder) with diffuse cohorts spreadup to 150 m away, but it is likely that the range of! Asparagus falcatus^! Asparagus virgatusCase study sitebird dispersal is much further. Although A. falcatusis quite distinct at maturity, at the seedling stageits sickle-shaped cladodes can be mistaken forother native seedlings such as Morinda jasminoidesA.Cunn. or Podocarpus elatus R.Br. ex Endl.Asparagus virgatus causes impacts to native groundcover and understorey plants. It is capable ofinvading almost all ecological communities thatoccur along coasts and coastal plains. It forms adense mat of water-hogging roots that can preventthe germination and establishment of other species.The root systems and foliage often co-mingle withdesirable vegetation, making access for digging andoff-target damage from foliar spraying problematic.The fine, fern-like foliage provides little surfacearea on which to apply chemicals. Infestations canspread beneath tree roots, rocks and logs, makingphysical removal very difficult.Both species grow in a range of coastalenvironments and can germinate in conditionsfrom full sun to more than 80% canopy closure.How are they managing the problem?Port Macquarie-Hastings Council is activelymanaging these two weeds in public bushland,106

This A. virgatus has recovered from a recent flood that covered it insilt and water. As its roots are heavily mingled with rainforest treeroots, digging is not feasible, so foliar spray will initially be appliedroad reserves and Asset Protection Zones and onprivate land by way of landholder engagementand education. Given the biological differencesbetween the two species, the approach tomanagement has also differed.Asparagus falcatusTo date, all located individuals of A. falcatus havebeen accessible and able to be treated. Whendetected, a first attempt is made to locate theinfestation source by ground-based inspection ofthe surrounding area. This is easier in bushlandareas, but much more difficult in urban and periurbanareas. Delimiting infestations of new andemerging weeds remains extremely resourceconstrainedand surveys may under estimate thetrue extent of the weed. Consideration is givento factors such as the likely vector(s) of dispersal,proximity-to-patch (the ‘pull factor’) and possiblecorridors and stepping-stones for seed dispersal atthe sub-landscape level. When located, records aremapped into a GIS layer to make later treatmenteasier as well as increase the understanding ofpossible sub-landscape level distribution patterns.For a given infestation, all cohorts are treatedwithin 12 months of detection. Plants aretypically treated by using the ‘crowning’ method(crown removal) and removing as much fruit aspracticable. Stems are left hanging out of contactwith the soil. If resource constraints do not allowfor removal in the first instance, foliar applicationof herbicide may be used to retard growth (and killoff some individuals) and limit further impact.Asparagus falcatus growing in marginal Casuarina glauca forestnear Lake Cathie, New South WalesAlthough more time consuming, Council has foundthat crowning is entirely effective and preferablewhen working in marginal swamp oak andriparian areas, when herbicide application may beunsuitable or undesirable.After an initial treatment, sites are usually revisitedwithin 1 to 6 months for any necessary retreatment.Ongoing monitoring is implemented and the sitetreated annually to remove any new individualsand – in bushland areas – facilitate naturalregeneration.To date, only small infestations of A. falcatus havebeen found and ‘best practice’ methods are beingused to locate, map, control, and monitor all sites.If the situation were to get ‘worse’ (i.e. increasein abundance and/or impact) and many denseinfestations were found, council would revise weedrisk assessments and adopt a different approachto management that focuses on protecting priorityareas. This may mean the focus shifts from a solelyeradication-centred technique being applied inall cases (labour intensive crowning and removal)to a combination of techniques that reflect thedual objectives of targeted eradication on somesites (typically outliers and new infestations) andsuppression/gradual reduction on others (large/founder populations). These integrated techniquesmay include crowning, basal barking and foliarspraying. However, eradication remains the goal atpresent.107

Asparagus virgatus single crown separated from running rhizomeNote: crowning knife is approximately 300 mm longAsparagus virgatus crowns connectedAsparagus virgatusPhysical removal of this weed is often verydifficult, due to the way in which its root systemcan spread beneath the roots of nearby vegetationas well as other objects such as rocks, logs andother structures (e.g. fences). Most infestationsare therefore being suppressed using foliar spraytreatments with hand gun application of 5–15 gmetsulfuron-methyl per 100 L water plus theadjuvant Pulse ® . While the lower rate gives aslower, but higher percentage kill, it can limitthe suite of other weeds that can be controlled.Therefore, under average conditions where a rangeof weeds may be targeted (e.g. other asparagusweeds, Lantana camara, Chrysanthemoidesmonilifera (bitou bush), Nephrolepis cordifolia(L.) Presl (fishbone fern), Ageratina adenophora(Spreng.) R.M.King & H.Rob. (crofton weed), andRubus fruticosus aggregate (blackberry)), 10–15 grates are usually applied.The treatment is monitored for efficacy andthoroughness and, within 6–12 months after initialcontrol, follow-up foliar spraying or grubbing(where appropriate) is undertaken. With thisapproach, the council is gradually reducing theextent of each patch and preventing plants fromflowering and setting seed.Two less weeds to worry aboutPort Macquarie-Hastings Council uses GIS to helpmap and monitor the reduction in the extent andabundance of these two weeds.Asparagus virgatus two crowns, connected by rhizomeAsparagusstemsTree rootRhizomeAsparagus virgatus stems and rhizomes running beneath tree root‘In every instance we approach the managementof Asparagus falcatus and A. virgatus from thesame perspective – that is, we weigh up the costof managing a small problem now versus a largeproblem later.’ Peter Michael, Port Macquarie-Hastings Council.108