Invasive Forest Pests and Disease
Spotted Lanternfly
In 2022, the spotted lanternfly, an invasive plant pest that is native to Asia, was confirmed in Lucas County. This insect is a destructive pest of grapes, hops, and apples, as well as several other species. Its primary host tree is the invasive Ailanthus or “tree of heaven,” that also is found in our area. Adults which have bright red, tan, white and black wings, can be seen in late summer into fall.
Click the links below for more information on identifying and reporting this exotic insect pest:
Emerald Ash Borer
The Emerald Ash Borer (EAB) is native to Asia and was accidentally transported to the U.S via wooden shipping material around 2003. Adult beetles are iridescent green in color and measure between 7.5 to 13.5 millimeters long. Larvae are white to cream-colored and are much longer than the adult beetles. The adults emerge in May or early June and have a one year lifecycle. They feed on leaves of ash trees, creating small irregularly shaped patches on the edges. After feeding, adults mate and females lay eggs 1-2 weeks later in cracks and crevices of the bark on tree trunks or branches. Seven to ten days later, larvae begin to chew through the bark. They feed for several weeks and create an S-shaped gallery below the bark that gets wider as they develop, overwintering here.
In April or May, they pupate into adults and one to two weeks later the new adults exit the tree creating a D-shaped hole. EAB spreads primarily through flight of the adults and accidental movement by humans and has infested nursery stock, firewood and other wood products made from ash trees. Beetles are also good flyers and can reach new ash trees far from the tree from which they emerged. EAB larvae damage trees by boring into the trunks or branches. Beneath the outer bark of the tree are the xylem and phloem which transport water and nutrients throughout the tree. Feeding by larvae disrupts the flow of the xylem and phloem. Without normal flow of water and nutrients, branches die and the crowns become thin. Ash species native to Ohio like white ash and green ash typically die after three to six years from EAB infestation.
At Metroparks Toledo, many parks lost nearly all their mature ash trees by around 2010, greatly impacting the canopy composition and structure, and in many cases opening up the understory to invasive plants like reed canary grass.
For more information on EAB in Ohio, and research on impacts of EAB in Metroparks, use the links below:
- Is Emerald Ash Borer on the Rebound in Ohio? [Read]
- Fourteen years of swamp forest change following invasion by EAB [Read]
- Dynamics of surviving ash populations in areas long infested by EAB [Read]
- Using Dutch Elm Disease-tolerant elm to restore floodplains impacted by EAB [Read]
- Co-variation among vegetation structural layers in forested wetlands [Read]
- Species and landscape variation in tree regeneration and 17 years of change in forested wetlands invaded by EAB [Read]
Oak Wilt Disease
Oak trees at Wildwood Preserve Metropark, Secor, sites throughout the Oak Openings Corridor, and areas within Oak Openings Preserve Metropark have been suffering from a disease called oak wilt caused by a fungal infection that prevents water from reaching the tree’s leaves.
Oak wilt infects only oak trees. White oaks are moderately resistant, but red, black and pin oaks will, unfortunately, die within a single season of contracting the disease. The disease is spread in two primary ways: by root grafts that form underground between adjacent trees; and by sap-feeding beetles above ground, which can transport the fungal spores from an infected tree to new wounds that are leaking sap on an otherwise healthy tree.
One method to prevent underground spread is to use a vibratory plow to separate oak tree roots around infected trees, to preserve as many healthy trees as possible.
Just as there are many ways to treat human diseases, there are options for treating diseases in woodlands. As numerous oak trees have become infected with the oak wilt fungus, Metroparks decided on a two-fold plan to efficiently manage this serious, invasive disease: trenching with a vibratory plow to separate root grafts around infected trees, and removal of infected trees to prevent overland spread by beetles.
The method chosen results in no removal of healthy oak trees from the park. However, oaks that have recently died or are dying, will need to be removed before spring, as there is a chance for the fungus to spread to new trees. This combination of above- and below-ground methods is effective in eliminating the center of infection, minimizing oak losses over time and significantly slowing the rate of spread within the park.
For more information on the disease, click here.