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

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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
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