Dealing with Crape Myrtle Bark Scale
Crape myrtle bark scale, a new insect appearing on crape myrtle, has been found in
Arkansas and in Garland County.
Hot Springs, Ark. – Crape myrtle bark scale, a new insect appearing on crape myrtle, has been found in Arkansas and in Garland County. The insect was first noticed in a north Dallas, Texas, suburb in 2004. Although the exact taxonomy is still not known, the insect is most commonly referred to as crape myrtle bark scale (CMBS). Since the initial sighting in 2004, the insect has been spreading at an alarming rate across the Southeast. In October 2013, the insect was confirmed in Germantown, Tennessee (Memphis area), in Little Rock, Arkansas in January 2014, and in Hot Springs, Arkansas in 2015.
Crape myrtle bark scale is easy to identify since, in the U.S., it is the first and only known bark scale to occur on crape myrtles. The adult females appear as white or gray felt-like encrustations on small twigs to large trunks, often appearing near pruning wounds or in branch crotches on older wood. Up close, CMBS is white to gray in color and approximately 2 mm in length. Careful examination may reveal dozens of pink eggs or crawlers under some of the larger white scale covers. Most gardeners will be alerted to CMBS by black sooty mold which appears on the bark. The presence of sooty mold may confuse the diagnosis since that is also commonly associated with a significant aphid problem.
Based on our limited experience with this pest, it does not appear that CMBS will be easy to control, though soil-applied neonicotinoids do provide significant suppression. Our current best suggestions for control of this insect include:
• For heavily infested plants, wash the trunk and reachable limbs with a soft brush and mild solution of dishwashing soap. This will remove many of the female scales and egg masses and make insecticide control more effective. Also, washing will remove much of the black mold that builds up on the bark on infested trees.
• Horticultural oil has not yet been shown to be effective against this insect; however, a winter application of dormant oil to the bark and crotches of the plants where scales shelter may be beneficial. Be sure to use sufficient volume to allow for penetration behind loose bark and into cracks and crevices. Winter is an especially good time to treat for scales because a higher (winter) application rate can be used without damaging the plant. Thorough coverage of the tree is especially important when treating with oil.
• Application of systemic insecticides as a drench applied to the root zone has shown the most promise in tests to date. Systemic control is best when applied between May and July. When drenching the soil with a systemic insecticide, allow several weeks for the product to be distributed throughout the plant.
More information about crape myrtle bark scale can be found on our web site at www.uaex.edu and search for FSA 7086 under “Publications”. If you notice symptoms of scale insect infestation on your crape myrtles contact the University of Arkansas Cooperative Extension Service at 236 Woodbine, call 501-623-6841, or email Allen Bates at email@example.com.
Master Gardener Information
Master Gardener meetings are held on the 3rd Thursday of each month at the Elks Lodge. They’re open to the public and guests are welcome. For more information call the Extension Office at 623-6841 or 922-4703 or email Allen Bates at firstname.lastname@example.org.
Are you interested in joining an existing Extension Homemakers Club? EHC is the largest volunteer organization in the state. For information on EHC contact Jessica Vincent on 623-6841 or 922-4703 or email her at email@example.com.
We have several 4-H clubs for our Garland county youth who are 5 to 19 years old. For more information on all the fun 4-H activities that are available for our youth, call Linda Bates at the Extension Office on 623-6841 or 922-4703 or email her at firstname.lastname@example.org.
The Arkansas Cooperative Extension Service is an equal opportunity/equal access/affirmative action institution.
By Allen Bates
County Extension Agent - Agriculture
The Cooperative Extension Service
U of A System Division of Agriculture
Media Contact: Allen Bates
County Extension Agent - Agriculture
U of A Division of Agriculture
Cooperative Extension Service
236 Woodbine Hot Springs AR 71901
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