Preventative measures: Swearingen et al. (2002) recommend not planting Pyrus calleryana. The root stock of grafted plants can sprout and reproduce by crossing with the upper scion. Sucker growth should be promptly removed to prevent possible cross pollination with the scion (Culley & Hardiman, 2007).
Physical: Pull up seedlings by hand or with a gardening tool which helps capture the roots. Cut down trees and immediately treat entire surface area of cut stump with a systemic herbicide such as concentrated glyphosate or triclopyr, following all labeling instructions, to prevent resprouting. Adult trees can be girdled in spring or summer by cutting through the bark around the entire circumference of the tree at the base of the tree. Mowing is not effective because of likelihood of resprouting (Swearingen et al. 2002).
Chemical: Treat entire surface area of any cut stumps immediately with a systemic herbicide such as concentrated glyphosate or triclopyr, following all labeling instructions, to prevent resprouting. To prevent fruiting of adult trees, spray with ethephon during full bloom; only 95% effective (Culley & Hardiman, 2007).
1. Culley, T.M. and Hardiman, N.A., 2007. The Beginning of a New Invasive Plant: A History of the Ornamental Callery Pear in the United States. BioScience: Vol. 57, No. 11, pp.956-964. American Institute of Biological Sciences, 2007. (doi:10.1641/B571108)
Summary: This article is a comprehensive look into the growing invasiveness of Pyrus calleryana including history, biology, distribution, control, and implications of invasion of the species, (in the United States).
Available from: http://www.redorbit.com/news/science/1211665/the_beginning_of_a_new_invasive_plant/index.html [Accessed on 18 February 2008]
2. Culley, Theresa M. and Nicole A. Hardiman., 2009. The role of intraspecific hybridization in the evolution of invasiveness: a case study of the ornamental pear tree Pyrus calleryana. Biol Invasions (2009) 11:1107–1119
3. Swearingen, J. and Reshetiloff, K. and Slattery, B. and Zwicker, S. 2002. Plant Invaders of Mid-Atlantic Natural Areas. National Park Service and U.S. Fish & Wildlife Service, Washington, D.C. pp. 82.
Summary: This source provides summaries of background, distribution, ecological threats, description, biology, prevention, and control of many invasive species in the Mid-Atlantic United States.
Available from: http://www.nps.gov/plants/alien/pubs/midatlantic/pyca.htm [Accessed on 18 February 2008]
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