Question
I live in Ft. Worth,TX (Northern TX) I have a crepe myrtle that is approx 10-12 years old.It has not bloomed as vigorously as previous years and some leaves are turning yellow and falling off since early summer.It generally looks unhealthy and I have noticed tiny brown specks on the bark that will rub off when touched.
I apperciate any help.thank you

Answer
Sounds like a scale type insect. These insects suck the plant juices from the plant and usually secrete a substance called honeydew that is high in sugar content and sticky. A 10-12 year old tree maybe too tall to treat with a spray insecticide so I would next spring treat the tree with an insecticide called Bayer Advanced Tree and Shrub Insect control. This is applied to the soil around the tree and the roots will transport it to the twigs and leaves and when the scale sucks the plant juices it is killed. Wait until the Spring that is the time the plant is moving water and nutrients to the new leaves.

You can spray the tree with a Horticultural oil this Fall after the leaves have fallen The entire tree needs to be covered with the spray (all limbs and twigs) If the tree is small enough to reach this may be a method you would prefer. Check with your local nursery fro these insecticides. Here is a web link for more information on the Bayer product.

http://www.bayeradvanced.com/product/Tree-Shrub-Insect-Control/concentrate.html