Biology Reference
In-Depth Information
sequence of events in the spread of Common crupina, so only a brief synopsis is
necessary here.
C. vulgaris,
a European annual, was first identified in north-central Idaho in
1968 - its first detection in North America (Stickney 1972). A cursory survey in
1970 found the plant confined to approximately 16 ha - a small infestation that
could have been swiftly eradicated. But no action was taken. Instead nine years
elapsed before even an eradication feasibility study was initiated, and six more
years slipped by before it was determined that Common crupina could indeed be
eliminated. Nevertheless, a detailed strategy of eradication was developed (Zamora
et al. 1989a), and an eradication manual was distributed (Zamora et al. 1989b), all
in preparation for the pending action. In the meantime, the plant had been added
to the Federal Noxious Weed List (Westbrooks 1993), which made it eligible for
federal funds for eradication. Finally in 1991, a federal/state task force proposed
spending five million dollars for Common crupina eradication, but by this time the
invasion had ballooned to cover > 25,000 ha. With a determined effort and appro-
priate strategy, eradication was perhaps still possible, but this effort was never
mounted as isolated public objection arose to the proposed use of the herbicide
picloram (Tordon
®
) for eradication. (The unsubstantiated claim was made that the
herbicide would leach into adjacent rivers and detrimentally affect native salmon.)
(R. Westbrooks, pers. comm.). At that point any attempt to control, much less
eradicate
C. vulgaris
, except locally, collapsed (D. Thill, pers. comm.).
Consequently, the spread of this invasive species in Idaho continues (T. Prather,
unpublished data).
The unfortunate tale played out with the failure of Common crupina eradication
holds several lessons. First, the time between initial detection and the marshalling
of resources for eradication was far too long, partially a consequence of a cumber-
some governmental response to a readily perceived environmental hazard. Once
assembled, the strategy and tactics for eradication might still have been successful,
except for the crucial failure to win strong public support.
3.8 Two High Stakes Current Eradication Campaigns
3.8.1 Chromolaena odorata in Queensland: High Stakes
in an On-Going Eradication Campaign
Chromolaena odorata
(Siam weed, Triffid), a native of South America, has been a
scourge for decades in much of the African and Asian subtropics and tropics (Holm
et al. 1977). The shrub is an aggressive competitor, and its seeds can be dispersed
by wind, water, and attached to cargo as well as a seed contaminant (McFadyen and
Skarratt 1996). Once established in a new range, it can rapidly spread under forest
canopies as well as along roadsides and stream courses. Siam weed's vegetative
growth is so prolific that not only does it provide competition for light, but also its
