Invasiveness Ranking System for Non-Native Plants of Alaska

Ecological Amplitude and Distribution ScoreHighly domesticated or a weed of agriculture (0–4) 1Myriophyllum spicatum is not an agricultural weed. It likely hasbeen used in aquatic gardens and aquariums (Bossard 2004).Known level of impact in natural areas (0–6) 6Myriophyllum spicatum is abundant, aggressive, and causedhigh impacts in streams, ponds, and lakes of Massachusetts,Connecticut, California, Minnesota, Virginia, Washington, andmany other states (Anderson and Spenser 1999, Bossard 2004,Jacono and Richerson 2003, Remaley 1998, Welling 2004).Role of anthropogenic and natural disturbance in3establishment (0–5)The plant thrives in areas that have been subjected to variouskinds of natural and manmade disturbance (Jacono andRicherson 2003, Remaley 1998, Welling 2004). It is particularlytroublesome in water bodies with nutrient loading, intenseplant management, and abundant motorboat use. Motorboattraffic contributes to natural seasonal fragmentation andthe distribution of fragments throughout lakes (Jacono andRicherson 2003).Current global distribution (0–5) 5Eurasian watermilfoil is native to Europe, Asia, and northernAfrica. It now occurs in North and South America, Australia,Greenland, Central and South Africa (Hultén 1968).Extent of the species U.S. range and/or occurrence of5formal state or provincial listing (0–5)It had been found in 33 states of the United States, and theCanadian provinces of British Columbia, Ontario, and Quebec(Jacono and Richerson 2004, USDA 2002). Myriophyllumspicatum is declared noxious in 12 states of the United States and1 Canadian province (Invaders Database System 2003).Total for Ecological Amplitude and Distribution 20/25Feasibility of ControlScoreSeed banks (0–3) 2Eurasian watermilfoil produces long-viable, often dormant seeds.Despite the high seed production, it is thought that germinationof seed is not a significant factor in reproduction (Bossard 2004,Remaley 1998).Vegetative regeneration (0–3) 3New plants develop from fragments of former plants (Bossard2004).Level of effort required (0–4) 4Once milfoil becomes well-established within a water body, it isdifficult or impossible to remove. In smaller water bodies, thereis some limited success using an aquatic herbicide. Other controlmethods include: harvesting, rotovation, installation of bottombarriers, and diver hand pulling (Anderson and Spenser 1999,Bossard 2004, Welling 2004).Total for Feasibility of Control 9/10Total score for 4 sections 87/97§B-86