Invasiveness Ranking System for Non-Native Plants of Alaska

Long-distance dispersal (0–3) 2The seeds are dispersed by flowing water, wind, and drifting snow(Juras et al. 2004, Parchoma 2004). Up to 26% of seeds remainedviable in dung (NAPPO 2003, Rutledge and McLendon 1996).However, the species lacks morphological adaptations for longdistancedispersal. There is no pappus on achenes.Spread by humans (0–3) 3The seeds are easily dispersed by vehicles and as a contaminant incrop seed and hay (Juras et al. 2004, Parchoma 2004).Allelopathic (0–2)UUnknownCompetitive Ability (0–3) 0Scentless false mayweed readily establishes on disturbed sites, butcannot compete with later successional forbs and grasses (Harrisand McClay 2003).Thicket-forming/Smothering growth form (0–2) 0Densities of 40 plants per square meter are common on crop fieldsin Canada (Harris and McClay 2003). It is not observed creatingdense thickets in Alaska (I. Lapina pers. obs.).Germination requirements (0–3) 3The seeds are able to germinate under a wide range of temperatureand moisture conditions. Germination is better under the canopythan on open, barren soil (Juras et al. 2004).Other invasive species in the genus (0–3) 0None.Aquatic, wetland or riparian species (0–3) 2Scentless false mayweed is found along irrigation ditches,shorelines, streams, and pond edges, as well as roadsides,perennial forage crops, pastures, lawns, gardens, and waste areas(Gubanov et al. 1995, Juras et al. 2004, Parchoma 2004).Total for Biological Characteristics and Dispersal 13/23Ecological Amplitude and Distribution ScoreHighly domesticated or a weed of agriculture (0–4) 4Scentless false mayweed is a one of the major weeds in wheat,lentil, mustard, and flax agriculture (Juras et al. 2004, Royer andDickinson 1999, Parchoma 2004).Known level of impact in natural areas (0–6) 0Scentless false mayweed does not appear to have a perceivableimpact on natural plant communities (Rutledge and McLendon1996).Role of anthropogenic and natural disturbance in1establishment (0–5)Scentless false mayweed is often associated with disturbedhabitats where there is little competition from establishedvegetation. Periodic disturbance by cultivation, livestocktrampling, or flooding promote establishment (Juras et al.2004). In Russia it is often associated with natural erosion alongstreambanks (I. Lapina pers. obs.)Current global distribution (0–5) 5Scentless false mayweed is native to northern and central Europe.It is introduced into North America and Asia. (Juras et al. 2004,NAPPO 2003).Extent of the species U.S. range and/or occurrence of5formal state or provincial listing (0–5)Scentless false mayweed is present in 26 northern states of theUnited States and in all Canadian provinces (Juras et al. 2004,NAPPO 2003, USDA 2002). It is listed as noxious in Washingtonand Saskatchewan (Invader Database System 2003). It isconsidered a weed in Alberta, British Columbia, Manitoba, andQuebec (Royer and Dickinson 1999).Total for Ecological Amplitude and Distribution 15/25Feasibility of ControlScoreSeed banks (0–3) 3The seeds remain viable in the soil for 10–15 years (Harris andMcClay 2003, Juras et al. 2004, Rutledge and McLendon 1996).Vegetative regeneration (0–3) 1Scentless false mayweed is reported to survive after removalaboveground growth (Juras et al. 2004).Level of effort required (0–4) 2Scentless false mayweed tends to occupy recently disturbedsites and it does not persist without continued disturbance, thuscontrol is seldom necessary (Harris and McClay 2003). However,multiple weeding treatments across years may be necessary toeliminate plants germinating from buried seeds. A combinationof mowing, tillage, and hand weeding can be used for preventintroduction to new areas. This species tolerates many commonherbicides. Biological agents have been released in BritishColumbia to control this species (Juras et al. 2004, Parchoma2004).Total for Feasibility of Control 6/10Total score for 4 sections 47/98§B-136