Azalea bark scale develops new appetite

This summer, Texas entomologists released a warning about a new menu item for the azalea bark scale -- crape myrtle. The aggressive pest (Eriococcus azaleae) has been increasingly attacking the ornamental tree primarily in Dallas County landscapes.

Look for sooty mold on the bark and branches. The pest will most likely appear near pruning wounds or in branch crotches, said Michael Merchant, extension specialist at Texas A&M University. In Dallas, it’s attacking both established and young trees.

The azalea bark scale is white to gray, and larger female scales “bleed” a pink liquid when crushed.

Azalea bark scale was first found attacking crape myrtles in Dallas three years ago, and it “has made a remarkably fast appearance as a new pest,” he said.

“Until now, crape myrtles have had a reputation for having few serious insect pests. It’s too early to know whether this insect will be an annually important pest of this important landscape plant,” he said.

Texas A&M Extension is working with the University of Florida to determine if this pest is a different Eriococcus species.

Texas control recommendations for azalea bark scale are still being developed. But Merchant and his colleagues have determined some control suggestions in the interim.

* During winter, apply dormant oil applications to bark and crotches of the plants. Thorough coverage of the tree is especially important when treating with oil.

* Time your summer spray activities to coincide with the presence of smaller scale insects. The presence of several large, white scales means it’s probably not a good time to spray. Wait one or two weeks and check plants again. March to mid-April is likely a good time to spray in most areas in Texas.

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For more: Michael Merchant, Texas A&M Extension, (972) 952-9204; m-merchant@tamu.edu.