Invasiveness Ranking System for Non-Native Plants of Alaska

Biological Characteristics and Dispersal ScoreMode of Reproduction (0–3) 3Corn spurry reproduces by seed. An average plant can produce2,000 to 7,000 seeds (New 1961, Trivedi and Tripathi 1982a, b).Long-distance dispersal (0–3) 1The seeds do not tend to spread long-distances, naturally.Occasionally they can be carried in digestive tracts of deer oron animal fur (New 1961, Guide to Weeds in British Columbia2002).Spread by humans (0–3) 3This species’ seeds can contaminate soil and crop seed (Volkart1924, Board 1952, Guide to Weeds in British Columbia 2002).The seeds can also be spread by vehicles or in mud on agriculturalequipment (New 1961).Allelopathic (0–2) 2Corn spurry causes strong inhibition of germination and growthof crops (Harrison and Peterson 1997, Peterson et al. 1998).Competitive Ability (0–3) 0Corn spurry has not been observed in closed plant communities.It is very susceptible to shade and is a less effective competitorthan perennial species (Fenner 1978a, b). In an experiment byFenner (1978b) the growth rate of corn spurry was higher in baresoil when compared to short and tall turf.Thicket-forming/Smothering growth form (0–2) 0Although corn spurry is capable of forming a dense stand, up to7,000 seedlings per sq. yard (Mann 1939) it is a short plant anddoes not have a climbing or smothering growth habit (Welsh1974, Royer and Dickinson 1999, Whitson et al. 2000).Germination requirements (0–3) 2Germination of corn spurry is markedly higher in bare soilcompared to turf (Fenner 1978b). About 43% of seeds germinatedin bare soil, 35% in short turf, and 10% in tall turf of Festuca rubrain experiment (Fenner 1978b).Other invasive species in the genus (0–3) 0Other species of Spergula have been introduced into NorthAmerica but none of them appears to be particularly weedy(USDA, NRCS 2006).Aquatic, wetland or riparian species (0–3) 0Corn spurry is a plant of disturbed open habitats. It typicallyoccurs on cultivated fields (Royer and Dickinson 1999, Guide toWeeds in British Columbia 2002), roadsides, and sometimes theseashore (New 1961).Total for Biological Characteristics and Dispersal 11/25Ecological Amplitude and Distribution ScoreHighly domesticated or a weed of agriculture (0–4) 4Corn spurry is found as a weed in cultivated wheat, oats, and flax(New 1961). Records of fossils seeds suggest that corn spurryhas been a common weed of flax from the Iron Age (Jessen andHelbaek 1944 cited in New 1961).Known level of impact in natural areas (0–6) 0Corn spurry has been recorded only in disturbed habitats (New1961). It is not known to cause an impact in any natural areas.Role of anthropogenic and natural disturbance in0establishment (0–5)Corn spurry requires bare soil for successful establishment(Fenner 1978a, b).Current global distribution (0–5) 5Corn spurry originated from Eurasia. It occurs throughoutEurope and also in Asia, North and South Africa, North andSouth America, Australia, and New Zealand (Hultén 1968). Ithas been recorded above the Arctic Circle (Natur HistoriskaRiksmuseet Database 2005).Extent of the species U.S. range and/or occurrence offormal state or provincial listing (0–5)Corn spurry is found in most American states, and nearly allCanadian provinces (Royer and Dickinson 1999, USDA, NRCS2006). Spergula arvensis is declared noxious in Alberta andQuebec (Rice 2006).Total for Ecological Amplitude and Distribution 14/25Feasibility of ControlScoreSeed banks (0–3) 3The seeds of corn spurry have been reported to remain viable for6–8 years in formerly cultivated soil (Chippindale and Milton1934, Roberts and Feast 1973).Viability of seeds was 18% after6.7 years, and less than 1% after 9.7 years in a seed viabilityexperiment conducted in Fairbanks (Conn and Deck 1995).Seeds of corn spurry were found viable after 22 years in soilbeneath pastures (Chippindale and Milton 1934).Vegetative regeneration (0–3) 2Corn spurry is able to produce new branches and often bearflowers and seeds when plants are cut off 2–3 nodes from theground (New 1961).Level of effort required (0–4) 0Mechanical methods (hand pulling, hoeing, or grazing) beforeseeds set can be successful in the control of corn spurry. Controlactions must be repeated as soil disturbance induces germinationof dormant seeds. Chemicals can be used, but corn spurry isresistant to several herbicides. Biocontrol methods are notdeveloped (New 1961, Guide to Weeds in British Columbia2002). Liming significantly reduces the density of corn spurry infield (Mann 1939).Total for Feasibility of Control 5/10Total score for 4 sections 32/100§5B-125