En EspaŅol

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
Can't find the answer in our existing FAQs, submit a question to Mr. Smarty Plants.
Need help with plant identification, visit the plant identification page.
rate this answer
10 ratings

Sunday - June 08, 2008

From: Helotes, TX
Region: Southwest
Topic: Trees
Title: Best time to trim oak trees to avoid oak wilt
Answered by: Nan Hampton


When is the best time to trim oak trees? Concerned regarding oak wilt if cut at wrong time. Ball moss is not harmful but will it help or harm if trees trimmed. These are large oak trees. Thank you.


The Nitidulid beetles that carry the fungus (Ceratocystis fagacearum) that causes oak wilt are most active from February through May. Their activity declines as the summer temperatures rise but they are still around June through October. Their activity also subsides during the colder months November through January. Definitely, do not trim your trees from February through June. Probably the best time to trim is during a particularly cold period in the November through January range. Alternatively, the very hottest months—July, August, September—would be a reasonably safe time to trim. No matter when you trim be sure to paint the wounds IMMEDIATELY with pruning paint or even latex paint.

Read "Guidelines for Proper Pruning to Prevent Oak Wilt Infection" by Kim Camilli (Oak Wilt Coordinator, Texas Forest Service) and "Studies on Pruning Cuts and Wound Dressings for Oak Wilt Control" by Kim Camilli, David N. Appel, and W. Todd Watson. Arboriculture & Urban Forestry 2007. 33(2):132-139. Also, visit the Texas Oak Wilt Information Partnership page for more information.

Regarding the Tillandsia recurvata (small ballmoss), they are epiphytes and not parasites; however, if they become too numerous on the limbs they can shade out leaves where photosynthesis occurs and interfere with the health of the tree. You don't really need to trim off the branches to remove the ball moss unless the limb itself is already dead. You can remove the ball moss from the limbs mechanically. There are also chemical controls, but unless the density is high, you probably can leave them where they are with no harm to the tree.


More Trees Questions

Are magnolia trees toxic for dogs?
February 05, 2014 - Del Mar, California- are magnolia trees, (their bark, roots, pods) toxic to small dogs? My Westie terriers are exhibiting lack of appetite and diarrea this late winter. Tonight I saw on our local n...
view the full question and answer

Tree for wet area in Central Illinois
July 30, 2010 - I live in Central Illinois. When it rains I get a lot of water in my backyard. What kind of tree would be best to plant in this wet area?
view the full question and answer

Chlorosis in sycamore in Kyle TX
August 04, 2011 - I'm trying to assist an elderly neighbor of mine with a plant issue. We have designated street trees in this community, our street being a Sycamore. The previous foreman out here called it a Mexica...
view the full question and answer

Failure to bloom of Magnolia in Webster FL
May 24, 2009 - Do all Magnolias Bloom? I live in Central Florida - transplanted a Magnolia 7 1/2 years ago. It is a beautiful tree - very healthy - at least 10-12 ft. It has never had a bloom!! I have another li...
view the full question and answer

Protecting storm-damaged pecan and black walnut trees in TX
June 29, 2015 - Several trees on our property in northeast Texas were uprooted by a tornado. A pecan tree with a circumference greater than 93 inches was carried to the ground. Although it is completely horizontal,...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2015 Lady Bird Johnson Wildflower Center