Biology Reference
In-Depth Information
Chapter 11
Sustainable Control of Spotted Knapweed
(Centaurea stoebe)
D.G. Knochel and T.R. Seastedt
Abstract Spotted knapweed is native to Eastern Europe, with a locally scarce but
widespread distribution from the Mediterranean to the eastern region of Russia. The
plant is one of over a dozen Centaurea species that were accidentally introduced into
North America and now is found in over 1 million ha of rangeland in the USA and
Canada. Land managers spend millions of dollars annually in an attempt to control
spotted knapweed and recover lost forage production, and meanwhile the plant perse-
veres as a detriment to native biodiversity and soil stability. These ecological concerns
have motivated intense scientific inquiry in an attempt to understand the important fac-
tors explaining the unusual dominance of this species. Substantial uncertainty remains
about cause-effect relationships of plant dominance, and sustainable methods to control
the plant remain largely unidentified or controversial. Here, we attempt to resolve some
of the controversies surrounding spotted knapweed's ability to dominate invaded com-
munities, and focus on what we believe is a sustainable approach to the management of
this species in grasslands, rangelands, and forests. Application of both cultural and bio-
logical control tools, particularly the concurrent use of foliage, seed, and root feeding
insects, is believed sufficient to decrease densities of spotted knapweed in most areas to
levels where the species is no longer a significant ecological or economic concern.
Keywords Biological control ￿ Biological invasions ￿ Centaurea stoebe L. ssp
micranthos ￿ Centaurea maculosa ￿ Knapweed ￿ Sustainable management
11.1 Introduction
Knapweeds and yellow starthistle, plants belonging to the genus Centaurea and the
closely related genus Acroptilon , are members of the Asteraceae that were acciden-
tally introduced into North America from Eurasia over a century ago. These species
D.G. Knochel (
) and T.R. Seastedt
Department of Ecology and Evolutionary Biology and INSTAAR, an Earth Systems Institute,
University of Colorado, Boulder, CO 80309, USA
david.knochel@colorado.edu
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