You must obtain permission from the landowner or management agency to perform any treatments. Public lands with hemlocks may have a management plan for their hemlocks, which could include chemical treatment, biological control, or both. You should not take it upon yourself to apply pesticide on public land, and if biological control is being pursued in the area you are concerned about, applying pesticide could interfere with those objectives.
The extent of these management activities depends on the resources and capacity of the managing agency, and HRI works on many state and some federal lands to implement their HWA management. If you see hemlocks that you are concerned about on public lands, you can reach out to the managing agency and express your concern and desire that the hemlocks be protected. They may be able to tell you what HWA management work they have been doing in the area you are concerned about. If the land you are hiking on is owned by a land trust or private landowner, we recommend you reach out to the landowner and find out if they are aware of the HWA on their hemlocks and the options available to protect the trees.
Additionally, you can advocate to state and federal policy makers on behalf of hemlocks and include information about the particular areas and trails that you are concerned about. Elected officials often respond to the loudest voices and personal stories.