Do you have crape myrtle bark scale?
There is one thing that every Oklahoman knows is going to happen when summer rolls around, and that is…it’s time for the crape myrtles to bloom! And that it’s going to be miserably hot for 2 months straight…..Even if you know nothing about plants, I can guarantee you that you have seen a crape myrtle. Beautiful, multi trunked trees ranging in size from 3 feet tall to well over 30, in various shades of white, pink, red, and purple, that continue to bloom well into late September. They are tough, durable, low maintenance trees that are a staple all across the southern half of this country.
Many of the most popular varieties that are available for purchase today were actually cultivated by a well-known research doctor from Oklahoma State University, Dr. Carl Whitcomb, and regardless of which cultivar/variety you choose, you will not be disappointed by the performance that these plants will put on throughout the summer.
In general, crape myrtles typically do not have many issues with insects or disease, with the exception of aphids and powdery mildew, but over the past few years a new pest has begun to emerge as a serious threat to the crape myrtle’s ability to perform. That pest is called crape myrtle bark scale, or CMBS for short. The bark scale is in a classification of scale insects known as felt scales, and has an appearance similar to a puffed up grain of white rice. These insects attach themselves to the bark and twigs of crape myrtles and begin to feed on the interior juices of the plant, while laying anywhere from 100-300 eggs!
Fortunately, scale is very easy to identify because in addition to the white insects themselves, they also leave behind a large amount of honeydew on the bark of the tree. If you’ve ever gone out and looked at your crape myrtle and seen a large amount of black tar-like substance covering the bark, that’s the residual honeydew. Heavy infestations will cause these crape myrtles to have weaker blooming and the residual honeydew on the bark makes them look unsightly. If left untreated for multiple seasons CMBS will eventually kill out younger crape myrtles, and allow for a greater spread of these insects around the community. The good news is that CMBS is easy to treat for with a consistent regimen of spraying.
Early in the year, February-March, it is recommended that you spray your crape myrtles with a horticultural oil to choke out any insects or fungal spores that are overwintering in the bark of the tree. Then from late April through the end of June or early July you’ll want to spray a combination of contact insecticides on your trees to keep them free of the scale insects. Another great way to protect your trees is by using a systemic insecticide and pouring it around the base of your trees as a drenching treatment.
The root system of the tree will absorb the product and then trans-locate it throughout the tree, effectively protecting it from the inside out. Systemic insecticides are readily available to the general public and are easy to use, look for the active ingredient imidacloprid on the bottle! As a homeowner it is important to pay attention to your landscape, do regular scouting of your plants for insects and disease and to thoroughly inspect the plants you are purchasing from the nursery before you buy them. By following these guidelines you are helping to ensure that future generations can continue to enjoy this wonderful plant for years to come!