Trees…They decorate our urban landscapes, live in our rural forests, and create beauty in our parks, cemeteries, and backyards. Yet they are all vulnerable to invasive bugs and evolved diseases that threaten their health.
Hemlock Woolly Adelgid is an invasive species from Asia that affects our hemlock forests all around the eastern United States. The insect affects the needles by feeding on the sap of hemlock shoots which starves the needles of nutrients. Left untreated the tree will start to lose needles, eventually resulting in death typically four to ten years after infestation. This invasive species is very small in the crawler phase and is difficult to detect with the human eye. The destruction caused by the Hemlock Woolly Adelgid can first be seen where the needles meet the twig. A white fuzzy egg mass collected at the base of these needles is a visible sign the tree is infected and the destructive process of the invasive has begun.
Pennsylvania Department of Conservation and Natural Resources - Forestry Archive, Bugwood.org
Oak Wilt is a tree disease brought on by a fungus that affects only oak trees. The most common symptom of Oak Wilt is the browning of leaves. Beginning at the tips/fringes of the leaf the dying of the leaf begins resulting in either a yellow or brown color. Under the bark a second symptom can be seen. Fungal patches develop under the trees bark and in some cases push the bark outward causing stress fractures to appear and emit a fermentation odor that attracts insects. The life expectancy of a tree infected with Oak Wilt can range from anywhere from a few months to a year depending on the oak species.
Minnesota Department of Natural Resources Archive, Minnesota Department of Natural Resources, Bugwood.org
Asian Longhorned Beetle is an invasive brought over to the United States from China. The Asian Longhorned Beetle is a wood boring insect, it has been found to feed on 24 different hardwood tree species. Infected trees will show signs of dieback, discoloration of leaves, the presents of beetle exit holes and perhaps the most obvious indicator of an infected tree: the beetle itself.
Melody Keena, USDA Forest Service, Bugwood.org
Perhaps the most famous invasive of late is the Emerald Ash Borer. Targeting the ash tree, EAB larvae live under the bark of the tree, feeding on the trees tissue effectively choking the tree of nutrients. In a desperate attempt to survive the ash tree may sprout new branches below the damaged tissues. The dying ash tree will show dieback of the canopy and deterioration of the bark around the dead and dying tissues. The presence of increased woodpecker activity on the west and south side of the tree is an indication the tree may have EAB.
Daniel Herms, The Ohio State University, Bugwood.org
Treating and preventing these threats is possible. Advancements in tree preservation have made it possible to affordably protect and save trees. One method of tree pest control is through tree injection. Tree injection is the process of inoculating the tree is similar to that of vaccines in humans. A tree is injected with a chemical tailor made to combat a specific ailment. Read more about tree injection at our blog What is Tree Injection?