Emerald Ash Borers are no longer a just a threat, they are here. It has been confirmed that the emerald ash borer (EAB) has hit New Jersey with ferocity. Bergen, Mercer, Union, Hunterdon and Somerset counties have all reported populations of this insect with Bridgewater being an area of high saturation. If you have ash trees on your property you need to read this column and act in a proactive manner to protect your trees.
Adults prefer to lay eggs on open grown or stressed ash, but readily lay eggs on healthy trees. Damage occurs in infested trees due to larval feeding. The serpentine feeding galleries of the larvae disrupt the flow of nutrients and water effectively girdling the tree. The tree will eventually no longer be able to transport sufficient water and nutrients to the leaves to survive.
White and green ash, the primary species of ash in our area, are killed quite rapidly if not protected. Many of the specialized predators and parasitoids that suppressed EAB populations in Asia are not present in North America. Without factors that would normally suppress EAB populations in its native range (e.g., resistant trees, predators, and parasitoid wasps), EAB populations are quickly rising to damaging levels. After initial infestation, all ash trees are expected to die in an area within 10 years without control measures. EAB populations can spread 12 miles a year. However, it primarily spreads longer distances by transport of firewood and other wood products that contain ash bark, which allows EAB to reach new areas and create satellite populations outside of the main infestation. EAB threatens the entire North American Fraxinus genus. It has killed tens of millions of ash trees so far and threatens to kill most of the eight billion ash trees remaining throughout North America. The loss of ash from an ecosystem can result in increased numbers of invasive plants, changes in soil nutrients, and economic disaster.
Identification and Life Cycle
Adult Emerald Ash Borers are bright metallic green and when they reach 0.33 inch long and 0.063 inch wide the adults begin to emerge from trees. After emergence, adults feed for approximately one week on ash leaves in the canopy before mating. Males hover around trees, locate females by visual cues, and mate. A typical female can live around six weeks and lay approximately 40–70 eggs, but females that live longer can lay up to 200 eggs. Eggs are deposited between bark crevices, flakes, or cracks and hatch about two weeks later. After hatching, larvae chew through the bark to the inner phloem, cambium, and outer xylem where they feed and develop. By feeding, larvae create long serpentine galleries. Fully mature larvae are 1.0 to 1.3 in long. In fall these larvae excavate chambers about 0.49 inch into the sapwood or outer bark. These larvae develop into pupae and adults the following spring. To exit the tree, adults chew holes from their chamber through the bark, which leaves a characteristic D-shaped exit hole.
Treatment
Insecticides with active ingredients such as imidacloprid, emamectin benzoate, and dinotefuran are currently used since they are systemic and remain effective for one to two years depending on the product and application method. Ash trees are primarily treated by direct injection into the tree or soil drench. These insecticides cannot be applied by homeowners and must be applied by licensed applicators. It is highly recommended you speak to companies who specialize in Emerald Ash Borer control.
Please contact Tree Dr. with any questions or to schedule a consultation at www.TreeDrNJ.com