Scioly.org

[img]http://www.pestid.msu.edu/wp-content/uploads/2015/01/Spotted-knapweed-rosette.jpg[/img]
1. names
2. when, how, and where was it introduced
3. Is there any biological control, Chemical control, Mechanical control, or Cultural control?  Describe them and note which one is most effective
4. This plant is very effective at forming monotypic stands.  Give the main reason why this is the case.

1. Spotted Knapweed, [i]Centaurea stoebe[/i]

2. First introduced to North America in the 1890s as a contaminant in alfalfa seed from Asia Minor (though the only specific account of where that I have found is Victoria, British Colombia in 1893, but in ship ballast soil). In the U.S. was first reported at San Juan Islands, Washington in the early 1920s.

3. All of those types exist. Cultural control helps prevent the introduction of spotted kanpweed to an area through maintaining competitive native vegetation. Because of the fact that it aids in prevention, it is in general considered the most effective, though it can only prevent introduction where it has not already occurred (it may create competition with current infestations though).

Mechanical control through hand pulling or mowing is most effective for small populations. When pulling by hand, remove the entire taproot if possible (and wear gloves, as it may cause contact dermatitis in some individuals, such as myself...). The ideal time for mowing of shoots is just prior to flowering or early into it (in other words, before seed production).

For biological control, at least thirteen insect species and one fungus have been released in North America. The seed‐feeding weevils,[i] Larinus minutus[/i] and [i]L. obtusus[/i] and the root‐mining weevil [i]Cyphocleonus achates[/i] are the primary biocontrol agents used. Other pathogens are known to attack spotted knapweed, including the black leaf blight fungus [i]Alternaria alternata[/i], a common soil fungus [i]Sclerotinia sclerotiorum[/i], and a stem blight fungus [i]Fusarium avenaceum[/i]

For chemical control, application of a herbicide containing aminopyralid in the spring before the plant flowers is recommended. Applying 2,4-D to rosettes in the fall or early spring also is effective.

Chemical and biological treatment are more suited for larger infestations, though the specific control program would vary depending on the potential to harm desirable non-target species or otherwise contaminate the environment.

4. Spotted knapweed produces catechin, an allelopathic chemical, inhibiting the growth of surrounding plants.

I better not have misidentified this...

flies of genus urophora are also good biocontrol

[img]https://upload.wikimedia.org/wikipedia/commons/1/18/Potamopyrgus_antipodarum_2.png[/img]

[img]http://www.invadingspecies.com/wp-content/gallery/butternut-canker/credit-barb-boysen-july-06-2.jpg[/img]

[img]https://s3.amazonaws.com/user-media.venngage.com/469729-1bd7edd64ccbd79408b2b70fcf25d2ce.jpg[/img]

[img]http://www.iucngisd.org/gisd/image/ecology/1361046.jpg[/img]

B is butternut canker which has been successful due to lack of native tree resistance
C is round goby which has been successful due to a great food source provided by zebra mussels
D is formosan subterranean termite which is very effective due to large hive populations and prolific alate production
also new zealand mud snail has next to no native predators