Friday, May 21, 2010

Possible New Scale Found on Crape Myrtles in North Texas

This bark scale in the genus Eriococcus, is thought to be an exotic insect pest that has infested North Texas crape myrtles. These bark scales appear as white, waxy encrustations near pruning wounds or in branch crotches. Larger female scales “bleed” a pink liquid when crushed. Since this scale excretes honeydew, the limbs and leaves become sticky. In heavy infestations, black sooty mold will begin to grow on the truck and branches of the crape myrtle.
Currently, the crape myrtle bark scale has only been observed infesting crape myrtles in north Texas area (from South Dallas to Sherman). If you live outside this area and believe you have an infestation of this scale, please submit your sample or a picture of the infested crape myrtle to your local county Extension office or to Dr. Mike Merchant ( or myself ( at the Texas AgriLife Research and Extension Center, 17360 Coit Road, Dallas, TX 75252.

Some Control Options:

For heavily infested crape myrtles, it is recommended to wash the trunk and limbs with a soft brush and dishwashing soap solution to remove female scales and egg masses. Also, washing with the soapy water will remove some of the black mold.
Systemic insecticides such as those containing imidacloprid or dinotefuran as a drench applied to the root zone have shown good control when applied between the months of May and July. Also winter applications of dormant oil to the bark and crotches of the plants where scales shelter is an effective control option.

1 comment:

祐祥 said...