There are many kinds of scale. All suck out the nutrients of a tree and produce a sugary excrement that can create a sticky mess known as “honeydew” on your outdoor furniture and walkways. Lecanium scale is a soft body scale that is light brown and can be found on many species of maple, oak, birch, hawthorn, and elm trees. Stressed trees attract scale more than healthy, vigorous trees. So a good fertilizer program is recommended to maintain the health of your tree to help prevent a scale infestation.
There are a couple different methods that can be used to treat a scale problem. The first is a dormant oil that will suffocate the pest in their shell. This treatment is done in the very early spring, before leaves start to emerge. The second is an injection treatment that will send a chemical through the tree and as the pest sucks out the nutrients, they will suck up some of the chemical and die. This method is used later in the summer when the babies or “crawlers” are out on leaves sucking up nutrients.
Many people don’t notice a scale problem until their tree starts to turn black. That is called black sooty mold and there is another article describing that issue. Have your local Certified Arborist come out and take a good look at your trees to avoid these issues, and keep a nice and healthy landscape.