As spring eases into summer, tree insects such as scales and borers begin to rear their ugly heads. Certain trees are susceptible to certain insects, and now is the time for specialized treatments to protect them from pest infestations. On the radar for the coming months for Denver tree pros are scales, borers, aphids, and mites.
Scales are some of the hardiest and most insidious pests in Colorado, causing branch dieback and even death in the infested tree through the long-term removal of the tree’s sap. The European elm scale, Oystershell scale, Striped pine scale, Juniper scale, and other scales are tiny, armored insects that secrete a waxy material from the pores on their back. This coating not only protects them from the hazards of Colorado weather, but also insulates them from some sprays used to contain them.
Aphids and mites, as well as scales, are sucking insects that cannot digest the sugars in plant sap. They produce a liquid called “honeydew” that drips onto the lower branches of whichever plant they have taken over; these shiny, sticky leaves are clear sign of infestation. Aphids and mites prefer tender, green buds and can be found on any new growth on your plants. Keep an eye out for these signs, as early detection and the development of a treatment plan with professionals is best for preserving your woody plants.
Emerald ash borers tend to do the most damage to ash trees in their larval stage, between August and October. These borers can infest ash trees for years before visible signs of decline appear. Infestation symptoms include sparse leaves or branches toward the top of the tree, along with vertical splits in the bark and damage to the leaves from feeding. Honey locust borers and oak borers are also active during this season, after hatching from eggs laid underneath the bark of honey locust and oak trees.
It’s vital that trunk treatments, either injections or sprays, are applied at the proper time for effective treatment against these pests. Scale eggs hatch in June and July, where the nymphs (or “crawlers”) then reside on the undersides of tree leaves until late summer. Borers need to be sprayed when they are newly hatched and emerging from the bark. Trunk injections every other year is recommended for keeping borers at bay.
Trunk injections are a treatment that uses a special injection tool to place and seal insect control directly into the tree, allowing the tree to distribute a minimal amount of pesticide from root to leaf tip. Trunk sprays are applied only to the bark of the trunk and lower branches; however, foliage doesn’t need to be treated. Both methods are quick and effective, with low environmental impact.
If you think your trees may need treatment, contact American Arbor Care, your Denver tree, shrub, and lawn specialists, dedicated to tree and shrub health management. Call (303) 639-8584 for your pest assessment, evaluation, and resolution needs.