Scale Infestation of our Tulip Tree
We have a 4-story tulip tree that has become severely infested with scale insects. We'd like to know possible organic-based solutions. We have well water and make every attempt to use natural or organic solutions to problems to cause minimal harm to the environment or the wildlife we've worked hard to attract. The tree is too close to the road/driveway, power lines and our house for simple removal. It's started to drop a significant amount of leaves so far. We have not seen evidence of mold or cultivation of the bugs by ants at this point. Thanks!
Harford County Maryland
Sounds like you may be referrring to tuliptree scale and we have had several reports. Large populations on large trees may suffer leaf yellowing, premature leaf drop, and branch dieback. 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. Wasps will also feed on the honeydew.
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 not have a problem next season.
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.
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. 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 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. https://www.treesaregood.org/