Humans adores trees. But humans also migrate and trade, habits that led to the accidental introduction of insects and diseases that harm trees and alter the landscape. Examples are easy to find and may be outside your front door: American elms that once dotted streets across America succumbed to Dutch elm disease. Now all colors of ash species – black, green, white, pumpkin, and blue – are threatened by emerald ash borer. The already uncommon butternut tree, also known as white walnut, faces the possibility of extinction from a mysterious attacker. Many invasive insects and fungi come from regions where native trees have evolved to resist their attacks. When these species enter the United States, they find trees that lack this resistance. There's no immediate end to this dismal pipeline, but there is hope on the horizon.
Dutch Elm Disease Resources
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Search HelpUSDA. FS. Northern Research Station.
Select the non-indigenous forest pest to view maps depicting state and county distribution. Produced by: USDA, FS, Forest Health Protection, and its partners.
Oklahoma State University. Oklahoma Cooperative Extension Service.
See also: Plant Diseases-Topical for more fact sheets
North Dakota State University Agriculture and University Extension.
Alberta Invasive Species Council (Canada).
See also: Fact Sheets for more information about individual invasive species, including those listed as "Prohibited Noxious" and "Noxious" under the Alberta Weed Control Act
University of Massachusetts Extension. Landscape, Nursery, and Urban Forestry Program.
USDA. FS. Northeastern Area State and Private Forestry.
Natural Resources Canada. Canadian Forest Service.
IUCN. Species Survival Commission. Invasive Species Specialist Group.
USDA. FS. Northeastern Area State and Private Forestry.
University of Georgia. Center for Invasive Species and Ecosystem Health.