Watch out for crape myrtle scale

Published 7:00 am Sunday, April 26, 2015

A new scale infesting crape myrtles has made its way into Mississippi.  Crape myrtle bark scale is a relatively new insect pest that was first reported north of Dallas in 2004. Since then, it has spread east and has been reported in Shreveport and Houma, Louisiana. Last year there were infestations reported in Mobile, Alabama. There had been none found in Mississippi until March of this year when it was found on the Mississippi Gulf Coast.

Crape myrtle bark scale is a type of felt or bark scale. Its closest cousin is the Azalea bark scale, but that species has never been associated with crape myrtle. Current evidence suggests that the scale may be a migrant from Asia, which is common on crape myrtle in Japan and China.

One of the first signs of a crape myrtle bark scale infestation is a black (sooty mold) coating that appears on the bark of the trunk and on the branches of crape myrtles. Leaves and limbs may feel sticky from byproducts of the insect’s feeding.

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The insects appear as white, waxy encrustations that can occur anywhere on the plant, but most likely near pruning wounds or in branch crotches. Up close, the scale insect is white to gray in color. Large female scales ‘bleed’ a pink liquid when crushed. Careful examination may reveal dozens of pink eggs under some of the larger white scale covers.

If crape myrtle bark scale becomes a problem in our area there are some control strategies that can be used.

• For heavy infestations, use a soft brush to scrub reachable trunks and limbs to remove females, crawlers and eggs. This will improve the insecticides effectiveness and remove a lot of the black, sooty mold.

• Apply a systemic insecticide to the plants root zone during May and July. Systemic insecticides include dinotefuran, sold as Greenlight Tree and Shrub Insect Control with Safari or imidacloprid, sold as Bayer Advanced Garden Tree and Shrub Insect Control. Allow several weeks for these insecticides to work.

I hope this new scale insect doesn’t find its way into our area of Mississippi, but more than likely it will. If you detect crape myrtle bark scale on your crape myrtles, please give me a call.  We would like to track the movement of this new pest throughout the state.

Rebecca Bates is director of the Lincoln County Cooperative Extension Service. To contact her, call 601-835-3460.