Scale on Tulip Poplar Trees

Asked July 13, 2018, 11:13 AM EDT

I have a large number of very tall tulip poplar trees surrounding my house. It has been raining sticky honeydew all over everything this summer. I have found scale as shown in pictures on the lower branches surrounding the driveway. most of the other trees are too tall and the branches too high to even investigate. What can I do to help solve this issue? Any advice on treatments would be appreciated. Many of the trees are over 80 ft tall and the lowest branches are already above what I could remove with my pole saw.

Carroll County Maryland

3 Responses

The insects looks like tuliptree scale, a (soft scale) sucking insect. They excrete a honeydew as they feed and this fosters the growth of a black sooty mold. If there are ants on the tree or on the foliage, they tend the scale as they feed on the honeydew. This honeydew fosters the growth of a black sooty mold.

If you have ants, we recommend that you try to control them. You can purchase large outdoor bait stations and place around the base of the tree. Control helps to let the predators and parasites come in and help control the scales naturally.

It is recommended in the dormant season to spray a dormant oil spray (when the trees lose their leaves). A thorough spray will help control overwintering immatures. You may need to hire a certified arborist if the tree is too large to spray.

If you want to use a systemic herbicide to control the scale, you would have to work with an arborist or a landscaper who is a certified pesticide applicator. This would be in early spring. Some systemic insecticides are restricted for homeowner use now, as per the Maryland Pollinator Protection Act that became law in January 2018. You can find a certified arborist using the following website from the arborist association:


I have not seen ants, but I can put out traps and see if it helps. It sounds like the only treatments can be performed in the winter and early spring. So there is nothing I can do right now to reduce this population? It is a full infestation, every branch I have looked at on over 10 100 ft tall trees is completely covered.

Will this just come back next year if my neighbors do not all treat their trees as well? Should I have any concerns about the health of the trees? They are close enough to my house that if they die I would be in danger.

is this common in the area? I live in Carroll County. Is there concern this will spread if I do not act?

This has been a good year for tuliptree scale and we have had several reports. Large populations on large trees may suffer leaf yellowing, premature leaf drop, and branch dieback. In most years native parasites and predators keep the insect from being a pest. This is a native tree and a native insect where it may feed throughout the growing season. Populations can fluctuate from year to year and you may never a problem.

No control is recommended now. The trees are very large and oil and soap sprays can be phytotoxic to the foliage in high temperatures. Also, coverage is very difficult when there is foliage on the tree. Sprays are ineffective when eggs are present from August through September.

You will have to decide treatment based on the health of the trees and damage. If you want to treat, the best time is when the tree is dormant as mentioned above. If you are noticing decline, you may want to contact a certified arborist for the best way to proceed and to make sure the trees are not a hazard.