Minnesota is home to over 1 billion ash trees, more than any other state. Ash trees are known to be very ecologically and economically important to our state, providing food and habitats for wildlife, and even removing one can have far-reaching effects that can cascade through ecosystems.

Unfortunately, according to the Minneapolis Park Board, we could lose over 87 percent of our ash trees in the coming years, as close to 880 million of our ash trees are susceptible to the Emerald Ash Borer. 

Ash trees are deciduous trees belonging to the genus Fraxinus, which comprises about 65 species worldwide. These trees are commonly found in temperate regions of the Northern Hemisphere and are known for their graceful form, compound leaves, and distinctive bark.

To identify one, look for these signs:

• Leaf Arrangement and Shape: Look for compound leaves with several leaflets arranged opposite each other along a central stalk. Each leaflet has a short stem (petiole) and serrated edges. The leaflets are usually arranged in pairs, with an odd leaflet at the end, giving the appearance of a single compound leaf.

• Bark: Check the bark of the tree. Young ash trees typically have smooth, gray bark, while mature trees develop distinctive diamond-shaped ridges.

• Branching Pattern: Notice the branching pattern of the tree. Ash trees have branches that grow opposite each other along the stem. This opposite branching is a key characteristic of ash trees.

• Seeds: Look for clusters of winged seeds, known as samaras or keys, hanging from the tree. These seeds are a common feature of ash trees and can persist on the tree into the fall.

The Emerald Ash Borer (EAB), scientifically known as Agrilus planipennis, is an invasive beetle native to Asia that has wreaked havoc on ash trees across North America. Since its accidental introduction to the United States and Canada likely in the early 2000s, this destructive pest has spread rapidly, primarily through the transportation of infested wood products like firewood. It was first found in Minnesota in St. Paul in 2009.

The adult EAB is a metallic green beetle, about half an inch long, with a bullet-shaped body. It's the larvae, however, that cause the most damage. After hatching, EAB larvae tunnel beneath the bark of ash trees, creating S-shaped galleries as they feed on the inner bark, disrupting the tree's ability to transport water and nutrients. Over time, this feeding activity effectively girdles the tree, leading to dieback of the canopy and ultimately the tree's death.

Detecting the early signs of an EAB infestation is crucial for implementing control measures and preserving the health of ash trees. Here are some common indicators:

• Canopy Thinning: One of the earliest signs of an EAB infestation is canopy thinning or dieback. Infested trees may exhibit sparse foliage or reduced leaf density in the upper canopy. This occurs as EAB larvae disrupt the tree's vascular system, impeding the flow of water and nutrients.

• Epicormic Shoots: In response to stress caused by EAB feeding, ash trees may produce an abundance of small, twig-like shoots known as epicormic shoots along the trunk and branches. These shoots may appear below the canopy and along the main stem and branches.

• Vertical Splits in Bark: As EAB larvae tunnel beneath the bark, they create serpentine galleries, which can cause the bark to split vertically. These splits may be visible on the trunk and larger branches and are often accompanied by small D-shaped exit holes left by emerging adult beetles.

• Woodpecker Damage: Woodpeckers are natural predators of EAB larvae and may target infested ash trees in search of food. Heavy woodpecker activity, particularly concentrated around the upper trunk and branches, can indicate an EAB infestation. Look for peeling bark, holes, or patches where woodpeckers have removed bark to access larvae.

• S-shaped Galleries: If you suspect an EAB infestation, carefully peel back a section of the bark on affected branches or the trunk. Look for winding, S-shaped galleries created by EAB larvae as they feed on the inner bark. These galleries are a distinctive characteristic of EAB infestations.

Emerald Ash Borer Adult Beetles: In the summer months, adult EAB beetles may be visible on or near infested trees. These metallic green beetles are about half an inch long and may be seen crawling on the bark or foliage.

Our insecticide treatment plays a crucial role in preventing and controlling infestations of the EAB, specifically formulated to target and kill EAB larvae before they can cause extensive damage to ash trees, thereby protecting ash trees from infestation and subsequent damage. 

Our trunk injections are a common method of delivering insecticides directly into the vascular system of ash trees, where they can be transported throughout the tree and effectively target EAB larvae feeding beneath the bark. This method minimizes environmental exposure and reduces the risk of unintended harm to the tree.