This tiny, little, moisture-sucking bug makes its host ugly and can eventually kill it. It has many looks and many different hosts. This bug moves with the wind and is very persistent. I have listed a few types here but there are many more.
Pinon needle scale presents itself as tiny black bugs on the needles. A single needle can have more than 15 or 20 bugs on it. You can tell you have the bug when the needles start to brown from the inside towards the tip. Once this bug attaches itself to the needle, the needle will most likely die. Enough of these bugs and your tree will look thin and sickly. To treat for this bug, we use dormant oil, usually in late February or early March, depending on weather and bug activity. To defend against this bug, hose the trunk off with a hard spray, especially in the crotches and on the undergrowth of the tree where the rain doesn’t hit it. **
Euonymus (and Boxwood) scale presents itself as white specs like dandruff. With a really sick shrub, you will find heavy populations on the leaves, twigs and limbs. Treatment and Defense – Hosing this off can be a little harder but dormant oil works well in February, March or April. This bug also responds well to chemical treatment if necessary and we would not do that until after May or later. **
Sycamore scale presents itself as tiny little dots along the veins of the leaves. It can also leave a dew on your car if you park under it. A bad infestation will show as browning leaves and will cause premature leaf drop in the summer and fall. Treating with dormant oil is okay but this bug is active all summer long and dormant oil can only be used in spring temperatures. The most effective treatment is systemically* in early March. Here’s the rub. If your neighborhood has a lot of Sycamore Trees, your tree probably has or will have scale. It’s like taking your kids to daycare. Even the healthiest can get sick. And because this bug is so persistent, we treat many trees annually, even our own. **
Purple Leaf Plum scale can affect any Plum, Cherry, Apricot, Pear, Hawthorn, and others. It presents itself as very tiny dots on the twigs and leaves. It leaves a sticky residue that can stain your car, walls, and sidewalks, and it will turn the tree trunk black. Dogs and people often track into the house. Suffice it to say, it is just a mess! You can treat the tree with dormant oil in the spring or chemical treatment starting in May. This bug is very active in the summer and many customers treat more than once annually. **
Oak scale looks like tiny little snails. By the time you notice the bug is there, your tree shows severe signs. If you live in an area where there are few oaks, systemic treatment can be done (best in March) and the bug controlled in usually 2 seasons. **
Elm scale presents itself as sticky leaves and black trunk or limbs. This tree can sustain scale without showing real devitalization, but it leaves a mess on anything underneath it. We usually treat systemically* in March. It keeps the patio furniture clean and dew-free throughout the season.
*Systemic treatments are those done at the base of the tree. It takes about 2 weeks for the treatment to move through the tree depending on the size of the tree and the amount of water the tree gets. Systemic treatments only work when trees are well watered since the water is what pushes the chemical through the vascular system.
**The best defense is to make sure your tree gets plenty of water. A strong, healthy tree can defend itself. If the neighborhood is heavily populated with your host tree, you will have a hard time defending it and will most likely have to treat.
As always, if you have any questions, feel free to contact your friendly, neighborhood Arborista – I diagnose trees and I make the coffee in the morning. ;o)