Explore Plants

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
    
 

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
Not Yet Rated

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 Trees Questions

Trees to plant around horse corrals
September 07, 2010 - I would like to know what types of trees would be good to plant around my horse corrals.
view the full question and answer

Space for a desert willow in Odessa, TX
April 23, 2009 - I have a small planting space about 5X5 that is four feet in front of the side of my front door. It is right under the eaves of my house. It's rather an enclosed porch space. I have a new very sma...
view the full question and answer

Will non-native and invasive Mexican petunias grow under oak trees from St. Augustine FL
March 24, 2013 - Will Mexican Petunias grow under an Oak tree?
view the full question and answer

Dry browning leaves on Monterrey Oak from San Antonio
August 08, 2013 - I have a Monterey Oak that was planted four years ago and was doing great until the last two weeks. It has turned brown and the ends of the branches are very dry and brittle. The root flare was cov...
view the full question and answer

Repairing damage to Anacacho Orchid Tree in Austin
April 30, 2008 - Hi You Guys!! We have an understory Anacacho Orchid Tree in the front and my sweetie was trimming the big oak and dropped a branch down, splitting one of the large branches off the Anacacho. The wou...
view the full question and answer

Smarty Plants's Facebook profile Support the Wildflower Center by Donating Online or Becoming a Member today.

Mr. Smarty Plants wants you to be his Facebook friend. Click the Facebook icon to add yourself to Mr. Smarty Plants list of friends.