When sycamore trees fail to thrive, we often look at leaf diseases like anthracnose and powder mildew as the major culprits. While these diseases are easy to spot, there is an insect that is much harder to see that often times contributes to sycamore problems. Sycamore scale is a small (1/16”) scale that feeds mostly on leaf tissue. This reduces the vigor and overall health of the tree. When sycamores are weaker they tend to get leaf diseases worse, which continues the downhill spiral of tree health.

These tiny scale insects overwinter on the bark and in the duff below the tree, then move to the leaves during the early spring. As they establish on the leaves they begin feeding and reducing the ability of the tree to produce and store energy in the form of sugars. When they are quite established, you can often see little “pinpricks” on the leaves as you look through the canopy. Left untreated, the tree will slowly begin to decline.

While unchecked infestations of Sycamore scale typically do not kill a tree outright, the trees are weakened enough that other diseases more easily attack both the leaves and the twigs. Excessive leaf drop from leaf diseases and twig dieback from branch diseases can become problematic season after season.

A good program for preventing diseases, regular nutritional feeding and proper watering should also include insect prevention to keep these tiny scale insects from becoming a problem. If you are concerned about your sycamore trees your Arborwell arborist can inspect and develop a program that encourages a healthy tree and discourages insects pests like Sycamore scale.

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