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 SpartinaFig. 3. Field crew member mowing Spartina anglica with hand-held brushcutters.Fig. 4. Field crew member treating Spartina patens with backpack herbicidesprayer.<strong>of</strong> a treatment method. This allows for <strong>the</strong> adjustment <strong>of</strong>treatment methods for better control.The most imporant component <strong>of</strong> adaptive managementin Spartina eradication is consistent control from year toyear. Research has shown that invasive Spartina is highlyresilient and requires multiple years <strong>of</strong> consistent treatmentto cause substantial declines. In some instances inconsistentcontrol, specifically, when two treatment seasons werefollowed by a year without treatment, resulted in a 100% to500% increase in cover and number <strong>of</strong> tillers (Reeder andHacker 2004). This underscores <strong>the</strong> importance <strong>of</strong>consistently treating a chosen site year after year to achieveeventual reduction and eradication.EVOLUTION OF TOOLSOver <strong>the</strong> more than ten years <strong>of</strong> invasive Spartinaeradication efforts in Washington State, <strong>the</strong> treatment toolshave evolved and become more effective. In <strong>the</strong> beginning,crews treated infestations <strong>of</strong> all sizes with small hand heldbrushcutters (Fig. 3) and backpack herbicide sprayers (Fig.4). While <strong>the</strong>se tools are effective on small infestations andare still used to this day, <strong>the</strong>y are simply too slow foreffectively treating anything greater than a few hectares. Theeradication program in Washington now employs helicoptersand large, tracked amphibious machines to treat largemeadows, and airboats with high pressure herbicide spraysytems to treat scattered clones and re-growth. Thehelicopters, applying herbicides at low carrier volumes, 97lliters per hectare (l/ha) (10 gallons per acre [10 gpa]), cantreat more than 160 ha (400 ac) per day. While slower than<strong>the</strong> helicopters, <strong>the</strong> tracked machines with broadcastapplication systems are still able to treat upwards <strong>of</strong> 16 ha(40 ac) per day. Airboats may only be able to treat 3.2 ha (8ac) per day at most, but <strong>the</strong>y are able to manuever in <strong>the</strong>estuaries and on mudflats, allowing for rapid transportbetween scattered infestations and produce virtually noenvironmental footprint.Having <strong>the</strong> ability to treat large infestations quickly andeffectively has increased <strong>the</strong> success <strong>of</strong> <strong>the</strong> eradicationprogram in Washington .CONCLUSIONOver <strong>the</strong> past two years, <strong>the</strong> eradication program inWashington State has become more efficient and effective.In 2003, a total <strong>of</strong> 2,700 solid ha (6,695 ac) out <strong>of</strong>approximately 3,400 solid ha (8,500 ac) were treated(Murphy 2003). These treatments resulted in <strong>the</strong> first overallreduction in <strong>the</strong> statewide infestation. In 2004, a total <strong>of</strong>2,500 solid ha (6,200 ac) out <strong>of</strong> an estimated 3,000 solid ha(7,500 ac) were treated statewide (Murphy 2004). Managersare confident that <strong>the</strong> 2004 treatments will also result in aFig. 5. Helicopter herbicide application, Willapa Bay, Washington, USA- 226 -