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 ManagementTable 1. Summary <strong>of</strong> chemical control efficacy for Spartina in Willapa Bay from 1999 to 2003.Control methodYearGeneral locationin Willapa BayStem density Percent stem density frequency(#/0.25m 2 )±std. error <strong>of</strong> mean. 0 1 to 5 6 to 20 >20Glyphosate 9 kg/ha 2003 SE 21.0±3.0 20 13 22 44Glyphosate 9 kg/ha 2003 S 27.0±1.5 14 13 19 54Glyphosate 9 kg/ha 2003 SE 7.0±1.0 25 27 35 13Glyphosate 9 kg/ha 2002 S 16.8±2.8 25 15 25 35Glyphosate 9 kg/ha 2002 S 7.5±2.0 56 16 15 15Glyphosate 9 kg/ha 2002 S 13.0±1.3 19 15 31 35Glyphosate 9 kg/ha 2002 S 1.6±0.2 55 23 15 7Glyphosate 9 kg/ha 2002/03 S 6.0±0.7 59 16 16 9Glyphosate 38 kg/ha 2002 NE 7.0±1.0 75 7 5 18Glyphosate 38 kg/ha 2002 Mid Peninsula 1.7±0.3 60 30 10 0Glyphosate 38 kg/ha 2002 N. Peninsula 2.3±1.2 57 37 3 3Glyphosate 38 kg/ha 2002 N. Peninsula 5.0±1.8 53 27 12 8Glyphosate 38 kg/ha 2002 SE 2.7±1.1 74 14 7 5Glyphosate 38 kg/ha 2003 N 5.0±1.0 32 13 42 13Glyphosate 38 kg/ha 2003 Mid Peninsula 16.0±4.0 35 10 20 35Glyphosate 38 kg/ha 2003 Mid Peninsula 5.0±1.0 58 12 18 12Glyphosate 38 kg/ha 2003 SE 0.5 ±0.5 68 32 0 0Glyphosate 38 kg/ha 2002 SE 3.4±1.1 54 28 10 8Glyphosate 38 kg/ha 2002 N. Peninsula 6.8±2.1 60 20 15 0Glyphosate 38 kg/ha 2002/03 N 9.0±2.0 35 18 33 14Glyphosate 38 kg/ha 1999/02/03 N. Peninsula 1.3±0.5 83 10 8 0Glyphosate 38 kg/ha 2000/02 S. Peninsula 5.2±0.7 63 7 18 12Crushing+glyphosate 9 kg/ha 2003 E 8.0±2.0 47 13 25 15Crushing+glyphosate 9 kg/ha 2003 E 2.0±3.0 8 8 43 41Crushing+glyphosate 9 kg/ha 2002 SE 3.1±1.2 44 46 7 2Crushing+glyphosate 9 kg/ha 2002 SE 1.5±0.5 71 19 10 0Crushing+glyphosate 9 kg/ha 2002 SE 1.6±0.5 53 40 7 0Crushing+glyphosate 9 kg/ha 2002 SE 1.9±0.6 60 20 15 0Crushing+glyphosate 9 kg/ha 2002 N. Peninsula 6.8±1.7 53 40 7 0Crushing+glyphosate 9 kg/ha 2002 SE 2.8±1.0 73 15 15 7Crushing+glyphosate 9 kg/ha 2002/03 SE 0.5±0.5 85 15 10 0Crushing+glyphosate 9 kg/ha 2002/03 SE 2.0±2.0 100 0 0 0Crushing+glyphosate 9 kg/ha 2002/03 SE 6.0±1.0 51 18 22 9Crushing+glyphosate 9 kg/ha 2002/03 N. Peninsula 8.0±1.0 35 15 40 10Crushing+glyphosate 9 kg/ha 2002/03 SE 1.0±0.2 76 8 14 2Crushing+glyphosate 9 kg/ha 2002/03 SE 5.0±1.0 43 15 37 5Imazapyr 1.7 kg/ha 2003 E 1.0±0.7 82 15 0 3variability in control at <strong>the</strong> high application rate.Glyphosate applied at <strong>the</strong> same site in consecutive years didnot provide any marked improvement in overall control overa single year <strong>of</strong> treatment (Fig. 1). Crushing followed by <strong>the</strong>application <strong>of</strong> <strong>the</strong> high glyphosate rate did not provide anybetter control than glyphosate alone (Table 1 and Fig. 1).Similarly, multiple years <strong>of</strong> this treatment did not improvecontrol over that <strong>of</strong> a single year <strong>of</strong> treatment. Control withimazapyr was <strong>the</strong> highest achieved by any treatment (82%).Although <strong>the</strong>se results were obtained from a very limiteddata set, <strong>the</strong>y are very similar to those obtained over sevenyears <strong>of</strong> small plot research (Fig. 2). In contrast, <strong>the</strong> controllevel found at monitoring sites where resource agencies usedglyphosate was considerably less than that obtained fromresearch trials.- 251 -