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Biological Control of Diffuse Knapweed (Centaurea diffusa) and Spotted Knapweed (C. maculosa)

Published online by Cambridge University Press:  12 June 2017

Donald M. Maddox
Donald M. Maddox*
Affiliation:
Biol. Control of Weeds Lab., Agric. Res. Serv. U.S. Dep. Agric, 1050 San Pablo Avenue, Albany, GA 94706
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Abstract

Diffuse knapweed (Centaurea diffusa Lam.) and spotted knapweed (C. maculosa Lam.) presently infest approximately 1.5 million ha of pasture and rangeland in Washington, Montana, Idaho, Oregon, and California. The serious losses caused on lands where returns from herbicidal control are marginal or less prompted the testing and introduction of two strains of a seed-head fly (Urophora affinis Frlfld.) as a biological-control agent in these states. Over 27 000 flies were released in about equal numbers on both weeds during the years 1974 to 1977 and in 1979 and 1980. The fly became established in all states where it was released. The adult was found to disperse over 76 m from release point from 1974 to 1976, and to reduce the number of seeds per flower head in sampled heads by 80% in northern Washington and over 64% at the Heppner, Oregon site. A newly released moth (Metzneria paucipunctella Zell.) and a root-boring beetle (Spbenoptera jugoslavica Obenb.) are expected to cause additional pressure on these plants. The reproductive potential of the knapweeds is such that more natural enemies will be needed to provide enough stress to reduce these weedy species to an acceptable level.

Keywords

Natural enemiesseed-head flies
Type
Research Article
Information
Weed Science , Volume 30 , Issue 1 , January 1982 , pp. 76 - 82
Copyright
Copyright © 1982 by the Weed Science Society of America 

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References

Literature Cited

1. Andres, L. A. 1977. The economics of biological control of weeds. Aquatic Bot. 3:111–123.Google Scholar
2. Dix, R. L. 1961. An application of the point centered quarter method to the sampling of grassland vegetation. J. Range Manage. 14:63–69.Google Scholar
3. Fletcher, R. A. and Renney, A. J. 1963. A growth inhibitor found in Centaurea spp. Can. J. Plant Sci. 43:475–481.Google Scholar
4. Groh, H. 1944. Canadian weed survey. 2nd Ann. Rep. Can. Dep. Agric. 74 pp.Google Scholar
5. Harris, P. 1980. Establishment of Urophora affinis Frfld. and U. quadrifasciata (Meig.) (Diptera: Tephritidae) in Canada for the biological control of diffuse and spotted knapweed. Z. Angew. Entomol. 89:504–514. (Germany).Google Scholar
6. Harris, P. and Cranston, R. 1979. An economic evaluation of control methods for diffuse and spotted knapweed in western Canada. Can. J. Plant Sci. 59:375–382.CrossRefGoogle Scholar
7. Howell, J. T. 1959. Distributional data on weedy thistles in western North America. Leafl. West. Bot. 9:17–29.Google Scholar
8. Maddox, D. M. 1979. The knapweeds: their economics and biological control in the western states, U.S.A. Rangelands 1:139–141.Google Scholar
9. Popova, A.YA. 1960. Centaurea diffusa Lam., a steppe-pasture weed in the Crimea [English Translation]. Bot. Zh. (Moscow) 45:1207–1213.Google Scholar
10. Story, J. M. and Anderson, N. L. 1978. Release and establishment of Urophora affinis (Diptera: Tephritidae) on spotted knapweed in western Montana. Environ. Entomol. 7:445–448.CrossRefGoogle Scholar
11. Watson, A. K. and Renney, A. J. 1974. The biology of Canadian weeds. 6. Centaurea diffusa and C. maculosa . Can. J. Plant Sci. 54:687–701.CrossRefGoogle Scholar
12. Zwolfer, H. 1970. Investigations on the host-specificity of Urophora affinis Frfld. (Diptera: Trypetidae). Prog. Rep. Commonw. Inst. Biol. Control No. 25. 28 pp.Google Scholar