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Saturday - September 07, 2013

From: Gainesville, TX
Region: Southwest
Topic: Pests, Trees
Title: Problems with Shumard Oaks and Crepe Myrtle in Cooke Co. TX
Answered by: Jimmy Mills

QUESTION:

I have a Shumard Oak Tree that has been in the ground approx. ten years. It has done great, even passing up some of my older Shumards. In August it began to lose its leaves at an alarming rate. They are very green when they fall. They fall single or in clusters. The end of the tree stem is still attached. None of my other Shumards(5)seem to be affected. I live in Gainesville (Cooke Co.) Tx.,just west of I-35. Also my Crepe Myrtle has been attacked by some kind of "Aphid", the leaves are shiny and sticky. Then they turn yellow with black spots and fall. The Shumard is in the back yard, the Crepe is in the front Yard. Could they be related?

ANSWER:

The problems that you describe are not related, and have different culprits involved.

The Crepe Myrtle, although it is widely planted all over Texas and the southern US, is a non native from southeast Asia. You are probably right to suspect aphids to be the cause of your problem. I am going to refer you to a previous question from last August that explains aphids and honey dew, and contains several links that have even more information about aphids and their control.

For the Shumard Oaks Quercus shumardii (Shumard oak), three culprits come to mind. Two are types of longhorn beetles; twig girdlers and twig pruners. Since the fallen twigs have green leaves attached, twig pruners are more likely causing the damage. Examine the fallen twigs, and if you see a concave end break, cut the twig open; you should find the fat white round-headed borer.

However, if the twigs have a slanted cut end or a sheared-looking end, then squirrels are probably your culprits. (more info)