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.
Did you know you can access the Native Plant Information Network with your web-enabled smartphone?
Ask Mr. Smarty Plants is a free service provided by the staff and volunteers at the Lady Bird Johnson Wildflower Center.
rate this answer
Wednesday - June 09, 2010
From: Austin, TX
Region: Southwest
Topic: Diseases and Disorders, Transplants, Watering, Trees
Title: Texas Pistachio trees dropping leaves in Austin
Answered by: Barbara Medford
QUESTION:
I have several Texas Pistachio that are about 13 years old. Despite good rainfall in Travis county this year, they seem to be losing most of their new leaf growth now in early June. Leaves are simply yellowing and dropping much as they would in the winter. Any idea what the problem could be?ANSWER:
While Pistacia mexicana (American pistachio) is native to Texas, this USDA Plant Profile shows it growing in only one county in the Big Bend area. That doesn't mean it won't grow in Austin, because obviously they do, at least for 13 years anyway. If they had not gone ahead and leafed out in the Spring, we would have blamed the very unusual cold temperatures we had this past winter. That could still be the problem.
What we have to do is try to discover what happened between last year and this year that could be causing this. For instance, has some kind of herbicide or "weed and feed" fertilizer been spread on your grass to get rid of broad-leafed weeds? Trees are also broad-leafed plants, and a too-vigorous application or (in the case of spraying) a brisk wind might have caused the leaf drop. Of course, if the same conditions don't apply to all the trees showing stress, that is probably not the only cause of the problem. Another clue we found said that the pistachio could flourish for years in the right location,and suddenly die of root rot from too much moisture in the soil. Have you put in a sprinkler system or started wateriing more often? We had several dry years and then a more normal rainfall. If the drainage in your soil is not good, the roots of the pistachio could be drowning. Desert trees do not flourish in lush conditions.
Finally, take a good close look at the tree. While we found no documentation of disease or insect pests bothering this plant, it's always a possibility. Beyond that, we are out of ideas. If you are watering more, we would suggest you direct it away from your trees. You might try treating it like transplant shock, and trimming away some of the upper portion of the trees. If the roots are struggling, this could help them get the needed moisture up to the leaves so the leaves can continue to manufacture food for the whole plant. Don't fertilize.The last thing stressed roots need is stimulation to put on new growth when they are just trying to stay alive.
Fiinally, we suggest you contact the Texas AgriLIFE Extension Office for Travis County and see if they have encountered similar problems in the neighborhood.
From our Native Plant Image Gallery:
More Diseases and Disorders Questions
Yellowing leaves of Texas Sage (Cenizo) from Las Vegas NV
November 21, 2013 - Leaves of Texas Sage are turning yellow. Can you tell me why?
view the full question and answer
Soapberry Transplant shock symptoms
July 21, 2006 - Please suggest a cause & cure for general yellowing of the leaves of Western Soapberry when planted in the ground 20 miles NW of Austin (thin, poor clay over limestone). Trees still in containers are...
view the full question and answer
Possible reasons for death of Wax Myrtle (Morella cerifera) in Austin
April 04, 2006 - Several wax myrtles in my neighborhood appear to have died. Should we have the soil or tree checked for fungus, or should we atrribute the death to freeze or age of the trees?
view the full question and answer
Plant mistakes from Cedar Park, TX
April 09, 2014 - At our "Wilts End" in Cedar Park, TX. and are looking for a tall shrub/tree that will hide a 6-ft tall concrete wall and muffle the noise from a busy street. The wall forms a very wide-angled V shap...
view the full question and answer
Hypoxylon Canker removal in Austin TX
March 26, 2012 - I have several oaks that appear to have been killed by Hypoxylon atropunctatum from last summer's drought. Is it safe to cut them down in March or does that risk spreading Oak Wilt too. Should I ...
view the full question and answer
Support the Wildflower Center by Donating Online or Becoming a Member today. |