LSU AgCenter's Weekly Message

Managing Crapemyrtle Bark Scale: Part 1

In my last article, I discussed what crapemyrtle bark scale (CMBS) is. Managing CMBS has multiple components. This week’s article discusses non-insecticide aspects. The next will be about insecticide options. (It’s not just a matter of “what to spray,” so I want to have plenty of space to address the topic.)

First, if you’re thinking about planting a crape myrtle, consider whether you may want to choose an alternative. A couple of plants that fill a similar role in the landscape (small, flowering trees for sunny sites) include chaste tree (Vitex agnus-castus) and large cultivars of Chinese fringe flower (Loropetalum chinense), pruned into a tree form.

If you do decide you want to plant a crape myrtle, check the trunks and branches before bringing it into your landscape. Certainly, avoid plants that have black sooty mold on the trunk, but also check for the small, cottony coverings of certain CMBS life stages. As mentioned in the last article, the life stages that have the white coverings are immobile, so if you poke it and it moves on its own, it’s not CMBS.

Choose a sunny site for your crape myrtle. Full sun exposure may reduce CMBS as well as promote more flowering.

Washing trunks of crape myrtles with a soft brush and mild soapy water can help remove CMBS and associated sooty mold. This is unlikely to get rid of all the CMBS individuals, but it can quickly improve the appearance of the plant and reduce the number of insects.

Sometimes, certain shoots have particularly heavy infestations, so you can prune out and dispose of these. Of course, if you don’t want to deal with CMBS at all, you can remove the plant.

In the next article, I’ll discuss ups and downs of different insecticide options, including soil drenches with systemic products and sprays that target the crawler stage.

Let me know if you have questions.

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Dr. Mary Helen Ferguson is an Extension Agent with the LSU AgCenter, with horticulture responsibilities in Washington and Tangipahoa Parishes. Contact Mary Helen at mhferguson@agcenter.lsu.edu or 985-277-1850 (Hammond) or 985-839-7855 (Franklinton).