Proceedings of the Third International Conference on Invasive ...

<strong>Proceedings</strong> <strong>of</strong> <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on Invasive SpartinaChapter 4: Spartina Control and ManagementCONTROLLING INVASIVE SPARTINA SPP.: THE NEW ZEALAND SUCCESS STORYG. MILLERRanger – Biodiversity, Department <strong>of</strong> Conservation, Southland, New ZealandSpartina is being successfully controlled in <strong>the</strong> estuaries <strong>of</strong> sou<strong>the</strong>rn New Zealand. With anestimated 800 hectares (ha) (2000 acres [ac]) <strong>of</strong> <strong>the</strong> New River estuary near Invercargill beingaffected by Spartina in 1988, this has now been reduced to less than 1 ha (2.5 ac). Within <strong>the</strong> nexttwo years, we expect Spartina to have been eradicated in <strong>the</strong>se estuaries. Spartina was originallyplanted in <strong>the</strong> Invercargill district in <strong>the</strong> 1930s to reclaim land in <strong>the</strong> estuary for <strong>the</strong> increasedindustrial activities in <strong>the</strong> area. It wasn’t until <strong>the</strong> 1970s that Spartina was first acknowledged as aserious problem causing significant impacts on <strong>the</strong> estuarine values, including wading birds andshellfish habitats, and thus declared an invasive weed to <strong>the</strong> area. Various control techniques weretrialled starting in <strong>the</strong> early 1970s producing some good results but were discontinued in <strong>the</strong> mid1980s. In 1988 <strong>the</strong> newly formed Department <strong>of</strong> Conservation took over <strong>the</strong> responsibility for <strong>the</strong>control <strong>of</strong> Spartina and trials began to find a method to control its spread.Trials with different chemicals show Haloxyfop (registered as Gallant nf ) to be <strong>the</strong> most successfulherbicide with up to 95% kill on first application. Trials on application techniques have seen <strong>the</strong>combination <strong>of</strong> helicopter boom spraying <strong>of</strong> meadows and follow-up with an eight-wheeledamphibious-tracked vehicle (Argo), fitted with tracks and spray unit, as <strong>the</strong> most efficient methods<strong>of</strong> applying this chemical. These methods are now being used extensively around New Zealand.The New Zealand Department <strong>of</strong> Conservation has beeninvolved with <strong>the</strong> control <strong>of</strong> Spartina in Southland for <strong>the</strong>past 16 years and has had some significant successes in <strong>the</strong>fight against this invasive weed. This document summarizes<strong>the</strong> lead-up to <strong>the</strong> department’s involvement, <strong>the</strong> trial workundertaken, <strong>the</strong> results achieved to <strong>the</strong> present and <strong>the</strong> plansfor <strong>the</strong> future.Planting <strong>of</strong> Spartina started in <strong>the</strong> New River Estuaryduring <strong>the</strong> early 1930s to help reclaim parts <strong>of</strong> <strong>the</strong> estuaryfor industrial development. The initial plantings were <strong>of</strong> <strong>the</strong>sterile hybrid Spartina x townsendii, but <strong>the</strong>se plantings didnot prove very successful. In 1947, plantings <strong>of</strong> <strong>the</strong> speciesSpartina anglica were undertaken. These plantingscontinued until 1954 and proved to be very successful. In <strong>the</strong>following decades, <strong>the</strong> area covered by Spartina continuedto increase in an uncontrolled manner and spread to o<strong>the</strong>restuary environments within Southland.In <strong>the</strong> 1960s and early 1970s, concern was first raisedon <strong>the</strong> increasing spread <strong>of</strong> <strong>the</strong> infestation and <strong>the</strong> effect itwas having on wading bird habitat. In 1972, a committeewas established to look at <strong>the</strong> Spartina issue, and withfunding from <strong>the</strong> Invercargill City Council, trials wereundertaken to try to control <strong>the</strong> spread <strong>of</strong> Spartina.Early work using <strong>the</strong> herbicide Tandex (activeingredient karbutilate) by spray application provedsuccessful, but later work was less so, possibly due to siltbuild-up on Spartina leaves reducing <strong>the</strong> herbicide’seffectiveness. A method <strong>of</strong> soil injection was developed;although successful, it was very difficult, time-intensivework. Successes achieved during <strong>the</strong>se early controlapplications were due mainly to <strong>the</strong> dedication, perseveranceand plain hard work <strong>of</strong> a few key people.Aerial trials with <strong>the</strong> herbicides Herbex and Phytazol Awere undertaken, but <strong>the</strong> consistency <strong>of</strong> <strong>the</strong> results wasdisappointing. Due to <strong>the</strong> restructuring <strong>of</strong> local authoritieswithin Southland in <strong>the</strong> mid 1980s, fewer resources wereallocated to <strong>the</strong> Spartina control program. Infestations <strong>of</strong>Spartina again grew in an uncontrolled manner and so some<strong>of</strong> <strong>the</strong> earlier successes were lost.By <strong>the</strong> end <strong>of</strong> <strong>the</strong> late 1980s, it was estimated thatinfestations <strong>of</strong> Spartina within New River Estuary affectedsome 800 hectares (ha), approximately 20% <strong>of</strong> <strong>the</strong> entireestuarine area. In 1987, <strong>the</strong> newly formed Department <strong>of</strong>Conservation took responsibility for <strong>the</strong> control <strong>of</strong> Spartinawithin Southland.A new interagency partnership was developed betweenInvercargill City Council, Environment Southland (a publicenvironmental monitoring organization), and <strong>the</strong> Department<strong>of</strong> Conservation. With this approach, efforts could again befocused on methods to control Spartina, not only in <strong>the</strong> NewRiver Estuary but also in all Southland estuaries. Thispartnership continues to this day and is one <strong>of</strong> <strong>the</strong> reasonsfor <strong>the</strong> success <strong>of</strong> <strong>the</strong> program. As some <strong>of</strong> <strong>the</strong> previouslyused herbicides were now unavailable, this led to a newseries <strong>of</strong> trials being undertaken with new herbicides andapplication methods.One <strong>of</strong> <strong>the</strong> first herbicides tried was glyphosate. Whilstthis herbicide proved fairly successful and was used for a- 247 -