Hostname: page-component-78c5997874-xbtfd Total loading time: 0 Render date: 2024-11-17T14:37:10.753Z Has data issue: false hasContentIssue false
  • English
  • Français

Control of Orange Hawkweed (Hieracium aurantiacum) in Southern Alaska

Published online by Cambridge University Press:  20 January 2017

Steven S. Seefeldt  and
Jeffery S. Conn
Steven S. Seefeldt*
Affiliation:
USDA-ARS, Subarctic Agricultural Research Unit, University of Alaska Fairbanks, Fairbanks, AK 99775
Jeffery S. Conn
Affiliation:
USDA-ARS, Subarctic Agricultural Research Unit, University of Alaska Fairbanks, Fairbanks, AK 99775
*
Corresponding author's E-mail: steven.seefeldt@ars.usda.gov
Get access Rights & Permissions [Opens in a new window]

Abstract

Orange hawkweed is a perennial European plant that has colonized roadsides and grasslands in south-central and southeast Alaska. This plant is forming near-monotypic stands, reducing plant diversity, and decreasing pasture productivity. A replicated greenhouse study was conducted in 2006 and repeated in 2007 to determine the efficacy of six herbicides (aminopyralid, clopyralid, picloram, picloram + chlorsulfuron, picloram + metsulfuron, and triclopyr) for orange hawkweed control. Based on results of the greenhouse trials, replicated field studies were conducted at two sites each year in 2007 and 2008 with three rates each of aminopyralid and clopyralid to determine efficacy of orange hawkweed control and impacts on nontarget native vegetation. In the field, only aminopyralid at 105 g ae ha−1 (0.1 lb ae ac−1) and clopyralid at 420 g ae ha−1 controlled orange hawkweed consistently, with peak injury observed 1 yr after treatment. Control with clopyralid was slightly less than that provided by aminopyralid at all observation times, except at Homer, AK, in 2007, where there was a near-monotypic stand of orange hawkweed, and clopyralid did not remove all orange hawkweed plants. Aminopyralid controlled clover (Trifolium spp.), seacoast angelica (Angelica lucida), arctic daisy (Chrysanthemum arcticum), common hempnettle (Galeopsis tetrahit), and willow (Salix spp.) in the treated areas. Other plant species, such as grasses and some annual forbs, recovered or increased following control of the hawkweed. Clopyralid had less impact on nontarget species with most recovering the year after treatment. In a pasture system, where grasses are preferred to forbs and shrubs, aminopyralid has an advantage because it controls a broader array of forbs compared with clopyralid. In natural areas, where the desire to retain biodiversity and the aesthetics of multiple forb species mixed with grasses and willows is preferred, clopyralid will leave greater species diversity than aminopyralid.

Keywords

AminopyralidchlorsulfuronclopyralidmetsulfuronpicloramtriclopyrOrange hawkweed, Hieracium aurantiacum L. HIEAUarctic daisy, Chrysanthemum arcticum L. CHYARclover, Trifolium spp.common hempnettle, Galeopsis tetrahit L. GAETEseacoast angelica, Angelica lucida L. ANLUwillow, Salix spp.Alaskaexotic weedsgreenhousenonindigenous plantweed control
Type
Research
Information
Invasive Plant Science and Management , Volume 4 , Issue 1 , March 2011 , pp. 87 - 94
Copyright
Copyright © Weed Science Society of America 

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Literature Cited

[AKEPIC] Alaska Exotic Plant Clearing House 2009. Non-Native Plants of Alaska. http://akweeds.uaa.alaska.edu/. Accessed: November 4, 2009.Google Scholar
Carlson, M. L., Lapina, I. V., Shephard, M., Conn, J. S., Densmore, R., Spencer, P., Heys, J., Riley, J., and Nielsen, J. 2008. Invasiveness ranking system for non-native plants of Alaska. Juneau, AK U.S. Department of Agriculture Forest Service, Region 10, R10 Technical Publication 143. 218 p.Google Scholar
Conn, J. S. and Cameron, J. S. 1988. Persistence and carry-over of metribuzin and triallate in subarctic soils. Can. J. Soil Sci 68:827–830.Google Scholar
Conn, J. S. and Knight, C. W. 1984. An evaluation of herbicides used for broadleaf control in rapeseed. Efficacy, phytotoxicity, and soil persistence studies. Fairbanks, AK Agricultural Experiment Station University of Alaska Bulletin 62. 22 p.Google Scholar
Hitchcock, C. L. and Cronquist, A. 1981. Flora of the Pacific Northwest. Seattle, WA University of Washington Press. 730 p.Google Scholar
Lass, L. W. and Callihan, R. H. 1992. Response of yellow hawkweed to sulfonylurea and pyridine herbicides. Las Cruces, NM Western Society of Weed Management Research Progress Report. 22.Google Scholar
Miller, T. W., Lass, L., Callihan, R. H., and Thill, D. C. 1987. Response of meadow hawkweed to sulfonylurea and pyridine herbicides. Las Cruces, NM Western Society of Weed Management Research Progress Report. 4.Google Scholar
Sell, P. D. 1974. Hieracium. Pages 534. In Tutin, T. G., Heywood, V. H., Burgess, N. A., Moore, D. M., Valentine, D. H., Walters, S. M., and Webb, D. A. eds. Flora Europaea. Volume 4. Cambridge, UK Cambridge University Press.Google Scholar
[USDA-NRCS] U.S. Department of Agriculture–Natural Resources Conservation Service 2009. PLANTS Database. http://plants.usda.gov/ Accessed: November 4, 2009.Google Scholar
Voss, E. G. and Bohlke, M. W. 1978. The status of certain hawkweeds (Hieracium subgenus Pilosella) in Michigan. Mich. Bot 17 (2):35–47.Google Scholar
Wattenbarger, D. W., Belles, W. S., and Lee, G. A. 1979. Chemical control of orange hawkweed in grass pastures. Las Cruces, NM Western Society of Weed Management Research Progress Report. 21.Google Scholar
Wilson, L. M. and Callihan, R. H. 1999. Meadow and orange hawkweed. Pages 238–248. In L Sheley, R. and Petroff, J. K. eds. Biology and Management of Noxious Rangeland Weeds. Corvallis, Oregon Oregon State University Press.Google Scholar