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
Not Yet Rated

Wednesday - July 20, 2011

From: Arlington , TX
Region: Southwest
Topic: Diseases and Disorders, Shrubs
Title: Leaves on yaupon holly turning brown/black
Answered by: Nan Hampton

QUESTION:

Arlington TX Yaupon Holly has leaves on stems closer to the bottom of the plant and moving up that are turning brown/black. Is this a disease, over/under watering? There is black gummy soil, but it has been so hot and dry. The plant is in full sun during afternoon.

ANSWER:

There are molds (e.g., sooty mold) that blacken leaves on hollies such as Ilex vomitoria (Yaupon holly) as well as other landscape plants.  The mold forms on secretions of plant sucking insects such as aphids and mealybugs.  If it is sooty mold, though, you probably can recognize it fairly easily and it will wash off.   My strong conviction, however, is that this is a result of the extreme heat and drought that Texas is undergoing.  You can visit the U. S. Drought Monitor map to see that most of Texas is in "extreme" or "exceptional" drought conditions.  I don't know how much and how you are watering the tree, but when you do water the soil needs to get a thorough soaking—the equivalent of an inch or more of rain.  (The Texas Forest Service recommends 1-4 inches of water every 10 days.  Use a rain gauge or some sort of container under the sprinkler pattern to measure it.) This will insure the water seeps deep into the soil and it will reach the plants roots there and keep them from growing toward the surface.   Also, the roots generally grow out to at least the same distance as the spread of the tree—the drip line—so watering with a soaker hose at the drip line is an efficient way to get the water to the roots.  Be aware that it takes longer to deliver 1 or 2 inches of water using the soaker rather than a sprinkler.  Mulch spread around the tree can also help to hold in the moisture.  Here is an article, Mulching Trees and Shrubs, from North Carolina State University with good tips on mulching and here is an article from our website, Helping Plants Handle Summer Heat.

Of course, overwatering can be harmful to trees, too, with many of the same symptoms of yellowing and dying leaves.  If the soil you describe as "black gummy" is always wet and gummy then you probably are overwatering.  If your soil is always damp more than 4 or 5" down (use a screwdriver or similar sharp instrument to push into the ground), then you are watering too much.   Here is a an article, Watering Trees and Shrubs, with more information from the University of Arizona College of Agriculture & Life Sciences Cooperative Extension Program.

 

More Shrubs Questions

Germination of Sophora seeds, and Dodder identification in Kingsland, TX.
May 02, 2012 - Our Mt. Laurel has just produced seeds. Can those be scarified and planted now or do they have to dry out. Also what is the stringy orange substance that gets on bluebonnets and other wildflowers ...
view the full question and answer

Foundation garden in shade in Durham, NC
April 29, 2009 - I'm trying to replant a 3'x8' garden near the foundation of our house in Durham, NC. This part of the yard gets little, if any, sun and is mostly clay. I've tried adding compost and soil conditi...
view the full question and answer

Privacy Hedge Plant for CA
January 26, 2016 - We recently moved into a new home right on the border of Cherry Valley and Beaumont, Ca. We are at an elevation of 2,900 ft. We are looking for a plant that we can use as a privacy hedge along our bac...
view the full question and answer

Evergreen plants for a windbreak
June 13, 2008 - Our church has need to plant a windbreak. We would like fast growing native plants, preferably evergreen or really early 'leafers' to protect us from our windy season beginning in mid/late February....
view the full question and answer

Growing non-native Knockout roses and golden euonymus together from Crystal City MO
May 19, 2013 - Can you plant knock out roses and golden euonymus together?
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