Host an Event Volunteer Join Tickets

Support the plant database you love!

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
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

Will desert rose (Rosa stellata) survive in south Florida
July 30, 2008 - I have a mature desert rose and I wanted to plant it in the ground. I live in southwest Florida.I want to know will it survive and should I wait to plant it next year?
view the full question and answer

Wound from non-native date palm thorn Naples FL
November 12, 2012 - Was trimming my pygmy date palm when a frond fell and a thorn pierced my rubber gloves and stuck me in the web of skin between my thumb and forefinger. Did not see a broken thorn but area where struc...
view the full question and answer

Yellowing leaves on non-native Hibiscus rosa-sinensis
July 03, 2006 - I purchased a chinese hibiscus hiros small tree and after 1 month the leaves keep turning yellow. What's wrong? It's in a large pot and never outside below 60 degrees. Thanks.
view the full question and answer

Non-native Philadelphus Innocence mock orange from Paris TX
June 20, 2012 - What is the best place in the garden to grow Philadelphus Innocence mock orange in Paris, Tx? Also, how long after transplanting do flowers occur? Any tips appreciated
view the full question and answer

Milkweed and non-native goatweed in Austin
May 28, 2011 - Which parks or fields can we find many milkweed and goatweed in Austin, TX? I live in Austin, TX 78757.
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.