Host an Event Volunteer Join Tickets

Your gift keeps resources like this database thriving!

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
1 rating

Saturday - October 06, 2007

From: Burke, VA
Region: Mid-Atlantic
Topic: Diseases and Disorders, Pests, Trees
Title: Possible disease on Eastern Redbud
Answered by: Barbara Medford

QUESTION:

Our Eastern Redbud appears to be suffering from our recent drought. The leaves are turning brown in July/August on a few branches. A few black spots appear on the leaves before they turn brown. Other smaller Redbuds in our yard do not seem to be affected. Is this a disease, a drought protection strategy or both?

ANSWER:

We're assuming that what you have is Cercis canadensis (eastern redbud), as that is the only one in our Native Plant Database that is found naturally in Virginia. Plants native to an area are much more likely to do well in that area, which is why the Lady Bird Johnson Wildflower Center is focused on promoting and preserving plants native to North America.

This Florida Cooperative Extension Service website on the redbud has a great deal of information about the culture of the Eastern redbud, as well as some of the common causes of problems. The only reference we found to black spots on the leaves was in reference to too much rain, so that's probably not your problem. The Eastern redbud can be both an understory tree or stand in full sun, but if you've had a dry, hot summer and the tree in question is in full sun, it may be stressed by that. If that's the case, hopefully some deep watering by sticking a hose down in the surrounding soil and turning on a slow drip for an hour or so will help.

So much for the weather being the problem. How about disease and/or critters? Borers can attack the trunks of older or stressed trees. To prevent this, keep the plant vigorous, which is what you're trying to do in the first place. Scale insects can infest the tree, and can cause sooty mold, which might explain the black spots on the leaves of your tree. Webworms may defoliate parts of the tree in summer and fall. The caterpillars are the larval form of the tiger moth, and they build ugly web nests in the spring or fall. Ugly as they are, they rarely cause any lasting damage. Probably the biggest problem in redbuds is canker. Bark in the canker turns black and a crack forms between diseased and healthy brk. The fungus enters through wounds or dead and dying branches. There is no chemical control, but spread can be at least slowed down by pruning out diseased branches. And, finally, verticillium will attack and kill Eastern redbud.

So, now that we've convinced you that your tree is a rooted Emergency Ward, let's just hope that cooler weather, more water, maybe at least some cloudy days for shade will begin to perk up the patient.

 


Cercis canadensis

 

 

More Pests Questions

Defenses against imported red leaf beetles on lilies
August 06, 2007 - I've recently discovered small red beetles of some kind on my lilies, which they are happily devouring. I've been picking them off with my fingers and squashing them, but I'd like a better alterna...
view the full question and answer

Problems with beheaded non-native Gerbera daisies in Cooperstown, NY
May 31, 2009 - I planted my gerberas in my perennial bed - as usual. Something is beheading them and leaving the blooms along side the plant. Some of the bloom is eaten but most of it is right there. I have t...
view the full question and answer

Plants to repel mosquitoes from Leander TX
May 19, 2013 - What are the best plant for repelling mosquitoes in the Leander area? The land here is hilly and rocky.
view the full question and answer

Dog-proof grass from The Woodlands TX
April 26, 2013 - I am looking for a hardy grass that can tolerate female dogs urine. Zoysia was suggested but I am concerned about it being invasive. Any suggestions?
view the full question and answer

Problem with leaf cutting bees in Houston, TX
December 08, 2014 - I have four Arapaho crepe myrtle trees in my backyard and two have leaves, especially the young leaves, being eaten by something. I do not see ants of beetles on the leaves and have not seen any bees ...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.