En Español

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?

Share

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
2 ratings

Sunday - February 01, 2009

From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders
Title: Problems with wax myrtle in Austin
Answered by: Barbara Medford

QUESTION:

I have been struggling with wax myrtles for the last year! We live in NW Austin, The plants start off great and then thin out, leaves go brown, and die. I then cut off the dead wood in the hope that the plant will come back, but they always look straggly. I have used liquid seaweed, and sprayed the leaves. Would this be my problem? Initially they seemed to thrive on the seaweed, but now I am not so sure. They are only about 3 feet apart, is that too close? Should I prune, or replace?

ANSWER:

We are just as puzzled as you are. From personal experience, we have always considered Morella cerifera (wax myrtle) an excellent native choice for Texas, with few pests or other problems. About all we can do now is to look at various possible causes, and leave it to you to examine your shrubs and see if you can determine the true problem. 

To begin with, you referred to the bushes as thinning out, and then looking straggly. Our website on the wax myrtle (link above) refers to is as a "wispy, multi-trunked evergreen shrub." Perhaps you were expecting it to thicken up and become more dense, when that is not in the plant's nature to do so. However, that should not cause the dieback. There will always be some attrition in leaves, even in evergreen plants. Old leaves will die and drop off to be replaced by fresh new leaves. That is just normal.

Again, according to our Native Plant Database information on the wax myrtle: "Wax myrtle is a fast growing plant that tolerates poor drainage and drought. Essentially a shrub, it serves as an excellent screen plant. It is also good for wetland gardens. Height and legginess can be maintained with a line trimmer or the shrub can be allowed to develop into an airy shrub."  However, it is a high water user, at least until it's well-established, so you might not be watering it enough in our severe drought conditions.

Here are our ideas on what might have caused the problem and how (or whether) to treat them:

1.  Examine the undersides of the leaves for possible insect infestation. Scale, aphids and whiteflies all produce honeydew when they feed and this, in turn, attracts a sooty black mold. The mold itself can cause problems and is unattractive. We don't encourage the use of pesticides in a situation like this, but rather try a hard spray of water on the undersides of the leaves; once these bugs are washed off, they have difficulty getting back on. Or you can spray with a weak solution of Safer Soap.

2.  Examine the pruning wounds for signs of possible canker disease. This University of Illinois Extension website Cankers and Dieback Diseases of Woody Plants has a lot of information on identifying and treating cankers, including  pictures. 

3.  We suspect you're being too nice to your plants and over-feeding them. The advantage of using plants native to an area is that they have evolved to be able to take care of themselves. Wax myrtles, in particular, are sensitive to overuse of nitrogen fertilizer, and some of the symptoms you have described bear that out. We have heard of liquid seaweed as an organic fertilizer, but have no personal experience with it. It's just our opinion that it needs to stop. 

Check out these possibilities and see if you can detect and correct the problem on your own. We don't believe the spacing of the shrubs would be a problem. The wax myrtle likes sun to part shade for its light requirements, and prefers a slightly acidic soil, while the soil in Austin is pretty alkaline. If you decide it is the pH of the soil that is causing the dieback, although we think it unlikely, then you may want to replace the shrubs with a plant which thrives in alkaline soil. 


Morella cerifera

Morella cerifera

Morella cerifera

Morella cerifera

 

 

More Diseases and Disorders Questions

Foam on Salvia greggii in Austin
October 20, 2010 - I have 7 Salvia greggii plants. I am seeing a white foam like substance on tip of all of them (where flowers use to be). Any suggestions on what is happening to the plants?
view the full question and answer

Yellow, pale green leaves on Cedar Elms in Texas
August 30, 2008 - I have had several cedar elms of various sizes planted in our yard over the last 10 years. Only the largest has dark green, healthy looking leaves. All the others have yellowish, pale green leaves. Th...
view the full question and answer

Diseased non-native red tip photinias from Richmond VA
April 08, 2014 - Our red tip trees have a while substance on the bark at the base of each tree..look like some kind of fungus or mold, but we don't know how to get rid of it. Please help.
view the full question and answer

Problems with gaura in Kyle TX
May 10, 2011 - Gaura - I seem to have something going on with this plant. I've tried fungicide that also works on mealy bugs and spider mites, etc., but they're looking rather puny? Any suggestions? thanks
view the full question and answer

Keeping dogs and cats out of flower gardens
March 02, 2009 - Do you have any suggestions to keep the cats and dogs out of my flower garden? They either just walk through it, and trample everything, or sleep on the soft blooms and squish everything. I am despe...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | JOBS | SITEMAP | STAFF INTRANET
© 2016 Lady Bird Johnson Wildflower Center