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 ManagementPOTENTIAL FOR SEDIMENT-APPLIED ACETIC ACID FOR CONTROL OF SPARTINAALTERNIFLORAL.W.J. ANDERSONUSDA-Agricultural Research Service, Exotic and Invasive Weed Research, One Shields Ave., Davis, CA 95616;lwanderson@ucdavis.eduNote: This paper, presented at <strong>the</strong> <strong>Third</strong> <strong>International</strong> <strong>Conference</strong> on Invasive Spartina, was subsequently published in 2007. Thecitation and abstract <strong>of</strong> <strong>the</strong> published paper is provided below.CitationAnderson, L.W.J. 2007. Potential for Sediment-Applied Acetic Acid for Control <strong>of</strong> Spartina alterniflora.J. Aquat. Plant Manage. 45:100-105 [http://www.apms.org/japm/vol45/v45p100.pdf]AbstractSmooth cordgrass (Spartina alterniflora), a tall grass native to <strong>the</strong> east coast, has invaded Willapa Bay,Washington, and <strong>the</strong> San Francisco Bay, California. Management with glyphosate and imazapyr can beeffective, but in <strong>the</strong> San Francisco populations, applications in several sites are confined to short periodsin <strong>the</strong> fall in order to protect nesting habitats <strong>of</strong> Clapper rails (Rallus longirostris). Use <strong>of</strong> efficacioussoil-active herbicides could mitigate this restriction. Acetic acid, a readily degraded natural product, hasbeen shown to kill sediment-borne propagules <strong>of</strong> aquatic plants such as Hydrilla verticillata andStuckenia pectinatus. Effects <strong>of</strong> acetic acid on sediment-free rhizomes <strong>of</strong> S. alterniflora were examined.Exposure <strong>of</strong> 0.1, 1.0, 1.5% vol/vol acetic acid for a few hours to several hours resulted in increasedconductivity in distilled water compared to unexposed controls, indicating loss <strong>of</strong> cellular integrity andleakage <strong>of</strong> electrolytes. Regrowth from exposed rhizomes was significantly inhibited at higher (1.0% and1.5%) concentrations applied for 2 or 4 hr. When rhizomes that had been directly exposed to 1.5% aceticacid were transferred to outdoor conditions in Albany, CA, both new shoot number and average plan<strong>the</strong>ight were reduced by over 90% at nine months post-treatment. The exposure to all concentrations <strong>of</strong>acetic acid for 4 hr also led to reduced frequency <strong>of</strong> inflorescence production, thus potentiallydiminishing <strong>the</strong> dispersal capacity <strong>of</strong> <strong>the</strong> treated plants. Field trials are needed to determine if judiciousdrenching <strong>of</strong> sediments with acetic acid (e.g., at low tide) may have utility as an alternative to foliarapplied herbicides such as imazapyr and glyphosate.Keywords: soil-active herbicide, electrolyte, pore-water, HPLC, seawater, smooth cordgrass, vinegar.- 277 -