Have you heard that North American forests are under attack? Insects are the enemy; some native to the United States, while others we’ve imported. Each pest attacks very specific varieties of trees and can ravage entire forests. In addition to expanding naturally, outbreaks have spread when people move firewood over long distances.
Infestations can kill trees by the thousands, cost millions to control and even threaten entire species. As an example, the Chestnut blight in the early 1900’s all but wiped out the Chestnut tree. The devastation means lost jobs, diminishing wildlife habitats, and as supplies become scarce, wood prices will go up.
Here are some of the biggest threats:
- Black Walnut is being attacked by thousand cankers disease (TCD), which is an insect infestation that spreads a fungus. The insect is called a walnut twig beetle. It’s a progressive disease that kills a tree within two to three years. Confirmed populations are scattered throughout western states and Tennessee. TCD may be present wherever susceptible walnut species grow.
- Ash is threatened by the Emerald ash borer (EAB), an exotic beetle that was discovered in southeastern Michigan near Detroit in the summer of 2002. The larvae feed on the inner bark, disrupting the tree’s ability to transport water and nutrients. It’s established in the Midwest, and all North American ash trees are threatened.
- Maple, Birch, Poplar, Willow, Elm, Ash and other related hardwood trees are being killed by the Asian long-horned-beetle (ALB). It grows and reproduces within deciduous hardwood trees, eventually killing the host tree. ALB is native to eastern China, Japan, and Korea and was discovered here in 1996. The beetle is believed to have arrived in wooden packing material used in cargo shipments from China. The ALB is known to be in Massachusetts, Ohio and Toronto, Canada.
- Elm Dutch elm disease (DED) is caused by a fungus and is spread by the elm bark beetle (EBB). Native to Asia, the disease was accidentally introduced into America in the 1930s, where it has since devastated native populations of elms.
- Oak California Oaks are being plagued by the gold-spotted oak borer (GSOB) a half-inch-long beetle. The trees seem to have no natural resistance to the GSOB, and no natural enemies of the beetle have been found in the state. The risk is that it will spread beyond California.
- Pine More than a dozen insects that attack pines have been introduced to North America. Among the worst are mountain pine beetles (MPB) which affect pine trees by laying eggs under the bark. The beetles introduce blue-stain fungus into the sapwood that prevents the tree from repelling and killing the attacking beetles with tree pitch flow. The fungus blocks water and nutrient transport, killing the tree. The MPB outbreak in western states is severe.
Scary, isn’t it? State and Federal forestry services are working to contain these killers. You can help by being aware, buying wood locally and never transporting green wood or firewood across state lines.
