Proceedings of the Third International Conference on Invasive ...

Chapter 4: Spartina Control and Management<strong>Proceedings</strong> <strong>of</strong> <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on Invasive Spartinanumber <strong>of</strong> years, its effectiveness was <strong>of</strong>ten reduced whensilt and dirt covered Spartina leaves, although kill rates <strong>of</strong>50% to 60% were still achieved. Fur<strong>the</strong>r trials wereundertaken using <strong>the</strong> herbicide Gallant? (Haloxyfop-Rmethyl).This grass-selective herbicide was being used by<strong>the</strong> Department <strong>of</strong> Conservation at that time for <strong>the</strong> control<strong>of</strong> marram grass (Ammophila arenaria) on sand dunesystems along <strong>the</strong> Southland coast. Gallant proved veryeffective at penetrating silt and dirt with at least 90% killrates being achieved with a single application. Thissubsequently became <strong>the</strong> herbicide <strong>of</strong> choice and its use hascontinued to this day.Whilst an effective herbicide was now available, earlyapplication methods left something to be desired, provingcostly in time and resources. Initial work with a highpressurespray gun and 200 meter (m) hose mounted on atruck was slow and difficult, needing a team <strong>of</strong> six people tohaul a hose across mudflats. Trials using a hovercraft in1995 proved successful in allowing quick access to scatteredSpartina patches that previously had to be approached onfoot. This machine was fitted with a small spray unit andproved very effective. However, this form <strong>of</strong> transport wasnot able to travel across <strong>the</strong> now vast Spartina meadows. Soeven though <strong>the</strong> hovercraft had made work easier, <strong>the</strong>re werestill shortcomings. Fur<strong>the</strong>r trials were undertaken using anArgo, an all-wheel-drive amphibious vehicle, with extremelysuccessful results. When fitted with a small spray unit, thisvehicle allows one person to undertake control work across<strong>the</strong> vast majority <strong>of</strong> areas within <strong>the</strong> estuary environment.When fitted with tracks, this vehicle is capable <strong>of</strong> travellingover waist-deep mud. Whilst <strong>the</strong> Argo was an extremelyefficient vehicle, an effective method <strong>of</strong> herbicideapplication to <strong>the</strong> vast Spartina meadows was still sought.Trials with a helicopter fitted with a boom and valsecolfoaming nozzles, flying at a height <strong>of</strong> 1-2 m above <strong>the</strong> tops<strong>of</strong> <strong>the</strong> plant and at very slow speeds, proved very effectivefor this task.As a result <strong>of</strong> our experience acquired during all <strong>of</strong><strong>the</strong>se trials, we now had <strong>the</strong> right tools in <strong>the</strong> fight againstSpartina. These tools were:• an herbicide that was extremely successful in <strong>the</strong> harshestuarine environment,• a helicopter that could attack <strong>the</strong> vast meadows, and• <strong>the</strong> Argo to control smaller areas on mud and to followup on <strong>the</strong> helicopter work.The correct use <strong>of</strong> <strong>the</strong> right herbicide by <strong>the</strong> mostappropriate method at <strong>the</strong> right time has had tremendousresults, which we were able to replicate in all estuarieswithin Southland.Sixteen years ago, <strong>the</strong> control and eradication <strong>of</strong>Spartina seemed an impossible task. However, previouslessons and <strong>the</strong> development <strong>of</strong> some <strong>of</strong> <strong>the</strong> early pioneeringwork has led to <strong>the</strong> elimination <strong>of</strong> Southland’s Spartinainfestation.To achieve eradication <strong>of</strong> Spartina, it is crucial for anactive surveillance program to be undertaken to continue tosearch for previously unrecorded infestations. At <strong>the</strong> presenttime, <strong>the</strong> Spartina meadows and patches have beeneradicated from all estuaries within Southland—sparselyscattered individual plants are all that remain.Where such plants are discovered, <strong>the</strong> appropriatecontrol action needs to be taken at <strong>the</strong> appropriate time. Theuse <strong>of</strong> <strong>the</strong> Argo is now <strong>the</strong> mainstay <strong>of</strong> our treatmentoperations because it is time and resource-effective.In addition to present eradication work, monitoring <strong>the</strong>effects <strong>of</strong> Spartina removal on <strong>the</strong> estuary will need tocontinue.ACKNOWLEDGMENTSThis has been a brief overview <strong>of</strong> <strong>the</strong> work that has beenundertaken over <strong>the</strong> past 30 years to enable estuaries withinSouthland to approach <strong>the</strong> eradication <strong>of</strong> non-nativeSpartina. This would not have been achievable without <strong>the</strong>continuing support and cooperation <strong>of</strong> our partnerorganisations: Environment Southland, Invercargill CityCouncil, and Dow AgroSciences.In addition, a number <strong>of</strong> individuals have given support,advice and assistance from <strong>the</strong> beginning <strong>of</strong> this program.My thanks go to all who have been a part <strong>of</strong> it.- 248 -