Native Plants

Q. Who is Mr. Smarty Plants?

A: There are those who suspect Wildflower Center volunteers are the culpable and capable culprits. Yet, others think staff members play some, albeit small, role. You can torture us with your plant questions, but we will never reveal the Green Guru's secret identity.

Help us grow by giving to the Plant Database Fund or by becoming a member

Did you know you can access the Native Plant Information Network with your web-enabled smartphone?

Ask Mr. Smarty Plants

Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.

Search Smarty Plants

See a list of all Smarty Plants questions

Please forgive us, but Mr. Smarty Plants has been overwhelmed by a flood of mail and must take a break for awhile to catch up. We hope to be accepting new questions again soon. Thank you!

Need help with plant identification, visit the plant identification page.

rate this answer

Not Yet Rated

Tuesday - November 09, 2010

From: Dallas, TX
Region: Southwest
Topic: Trees
Title: Webbing on oak leaves and fuzzy yellow growths on leaf veins
Answered by: Nan Hampton and Eric Beckers

QUESTION:

I have a large red oak(?) and live oak that appear to have the same problem. Clumps of leaves all over the trees are covered by fine webbing and the leaves appear to be curling up and dying in the webs. I have not seen any worms in the webbing and the individual webs do not seem to cover as large an area as web worms that I have seen on other trees in the past. The leaves at the ends of the branches on the red oak are almost entirely covered by the clumps of leaves and webs. The same leaves have another issue on both trees. On the underside of the leaves there are rounded, fuzzy yellow growths on the leaf veins. Is it possible that I have 2 different diseases/insects at the same time? I thought about some sort of leaf galls and spider mites.

ANSWER:

I consulted Eric Beckers with the Texas Forest Service about the fine webbing on your oak trees and he said that he can't imagine anything other than webworm. The size of the web might have been kept to a minimum by a late hatch after the September rains followed by a very dry October. Lack of caterpillars could have been a sign of good predator activity (we had a bumper crop of wasps this fall!).

The fuzzy yellow growths on the underside of the leaves are most likely galls caused by a tiny wasp. Acraspis erinacei, Andricus quercusflocci, Andricus quercuslanigera, Andricus laniger, Andricus fullawayi and Andricus ignotus are all gall wasps that produce fuzzy galls on oaks. There is no evidence that your two problems are linked since these tiny wasps that produce the galls are not likely to be predators of the webworms.