En EspaŅol

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
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
1 rating

Wednesday - May 06, 2009

From: San Antonio, TX
Region: Southwest
Topic: Non-Natives, Diseases and Disorders, Trees
Title: Will Mountain Laurels be harmed by juglones from my pecan tree?
Answered by: Jimmy Mills

QUESTION:

Hi. I just bought a house. It has a big pecan tree at the edge of the front lawn next to the street. I guess it's about 25 feet from the front of the house. I was thinking of planting mountain laurels near my front windows, pretty far from the pecans, but I read on another forum that mountain laurels will not grow within 50 feet of a walnut tree. Doesn't the pecan have the same toxin as the walnut, and so would it be a bad idea to try mountain laurels in my spot? If not, what about loquats?

ANSWER:

The pecan Carya illinoinensis (pecan) is a member of the family Juglandaceae which contains the Hickories and Walnuts. Members of the family produce the chemcal juglone that is allelopathic  to some plants but not others. One role of the toxin is to prevent the growth of competing plants under the tree. It appears that the level of  juglone in pecans is less than in walnuts. 

You can see lists of plants susceptible to juglones and those tolerant of juglones from Michigan State University and Ohio State Univeristy. Mountain Laurel Kalmia latifolia (mountain laurel) appears on the susceptible list, but this is probably not the Mountain Laurel you have in mind (it doesn't usually grow in Texas). In San Antonio, Mr. Smarty Plants suspects that you want to plant Sophora secundiflora (Texas mountain-laurel) which is not on the susceptiple list, and would be a great addition to your front yard.

As for loquats; since the mission of the Ladybird Johnson Wildflower Center is to increase the sustainable use and conservation of native wildflowers, plants and landscapes, Mr Smarty Plants would prefer that you not plant loquats which have been introduced from Southeastern Asia.


Carya illinoinensis

Sophora secundiflora

Kalmia latifolia

 

 

 

 

 

 

 

 

 

 

More Non-Natives Questions

Sticky leaves on non-native weeping willow
August 03, 2008 - Our weeping willow trees look healthy but have sticky leaves that attach to everything. They sparkle/shine from this very sticky mess. They are watered regularly, are they getting too much water? ...
view the full question and answer

Possibility of invasiveness of blackberry bush
March 27, 2008 - I bought a blackberry bush from Home Depot last year. My sister said if I planted it in the ground it would take over my lawn. So I put it in a big planter up against my fence, but I'd like to put it...
view the full question and answer

Information about ice plant (Carpobrotus edulis)
May 06, 2008 - I recently planted some Carpobrotus edulis, Ice plant, and wanted to know if I can mulch or put stones around the entire garden and plants. They are a ground cover plant.
view the full question and answer

Non-native, invasive rescue grass in meadow garden in Smithville TX
September 20, 2012 - Despite numerous efforts, a solid field of cool weather rescue grass keeps desired wildflower and grass seeds from successfully growing on my "vacant" lot in town. I plan to I put out a 6 ml plasti...
view the full question and answer

Problem with Chinese Pistache tree
September 01, 2014 - We have a gorgeous Chinese Pistache in our yard, about 25 feet tall. We bought it for its gorgeous fall color. The problem is that it has never turned color for us. All the other pistaches in the neig...
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.
E-NEWSLETTER | BECOME A MEMBER | DONATE NOW | MEDIA | SITEMAP | STAFF
© 2015 Lady Bird Johnson Wildflower Center