Managing Hemlocks for HWA: What You Can Do

No landowner is happy to hear that an invasive pest species is present on their property. Consequences of pest infestations can include a reduction in property values, dangerous situations involving dead or damaged trees, and increased costs of managing a property in order to treat an infestation and protect forested lands. These and other issues can cause headaches for landowners, but there are some steps to take in advance of infestations to reduce the impact of those negative consequences. When it comes to HWA, there are several things that landowners can do to prepare for managing emerging infestations.

1. Keep tabs on your trees

You’ll want to know both where your hemlock trees are and their overall health in order to prep for HWA management. You’ll also want to know whether or not your trees are infested. If there is no HWA infestation present, there is no need to treat, but be sure to check back each year in case HWA does arrive. If HWA is present, treating right away will eliminate HWA in the tree and protect it for up to seven years. To look for HWA, find your hemlocks and check branches and twigs on all sides of the tree if there are reachable branches. If you have large trees, keep an eye on branches or twigs that have fallen on the ground from above as these can tell you what is going on higher in the canopy.

2. Establish priorities for management

Treatment prioritization is important for two reasons: there is a limit on the amount of HWA treatment product that can be applied per acre per year, and, if you have a large property, treatment cost can limit the number of trees you can treat. Marking priority trees can help you to organize management efforts and spread out treatments over time if needed. Priority trees can be the biggest, healthiest trees on your property, trees near water, trees that are important wildlife habitat, or trees near your home or other structures that you want to conserve. Ultimately, taking the time to establish those priorities in advance will help streamline management efforts when the time comes. If you would like help thinking through prioritizing your hemlocks, we have tools and assistance available.

3. Get your community involved

If you are part of a neighborhood group, lake association, outdoor club, or another community organization, consider setting up a fund to help your group members pay for HWA management. If your club or group has regular dues or fundraising goals, it can be useful to save for HWA treatments on a member’s property in the event of a local infestation. Treating your own trees is a great way to help protect your local hemlocks, and HWA treatments on a neighbor’s property can help protect your trees, too.

4. Know what resources are available to you

It is critical to know who you can reach out to in the event of an infestation including local pesticide applicators, foresters, and invasive species specialists. In the case of HWA, landowners can treat their own trees using a soil drench application of imidacloprid. There are other application options available to professional applicators that make the treatment process faster or allow treatments closer to water where a soil drench is undesirable. For more information on imidacloprid treatments and application methods visit the management section of our website.

Landowners looking for a licensed pesticide applicator may reach out to us at, or to their county’s Cornell Cooperative Extension office. Additionally, landowners should familiarize themselves with their regional Partnership for Regional Invasive Species Management (PRISM) team. In some cases, landowners may have treatment costs covered through small grants or special projects, depending on the location of the infestation and the other conservation interests on a given property.*

According to the Department of Environmental Conservation, 76% of New York’s forested lands are privately owned. For this reason, landowners play a vital role in forest stewardship in New York. You can help manage and slow the spread of HWA by keeping an eye on your trees and planning for hemlock conservation on your property.

Although spring is typically the best time for HWA treatments, fall is also a good time to treat. Get to know more about HWA management and start planning treatments on your property by visiting our HWA Management page.

*Landowners in the Adirondacks are especially encouraged to notify the NY Dept. of Environmental Conservation (NYS-DEC) if HWA is discovered on private property. Since this region is at the forefront of HWA infestations and has the densest hemlock forests in the state, it represents a vital conservation value. In these cases, DEC may treat trees on private property at no cost to the landowner to protect hemlock resources and prevent local HWA spread in the Adirondacks.