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?


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
Not Yet Rated

Saturday - March 30, 2013

From: Clarkridge, AR
Region: Southeast
Topic: Non-Natives, Edible Plants, Trees
Title: Will corn fall victim to allelopathy from hackberry in Clarkridge AR
Answered by: Barbara Medford


Will my corn be inhibited by a nearby hackberry and if so would it help to cut it down? I understand that sometimes the soil is full of the chemicals the tree produces.


What you are probably referring to is allelopathy, which is the production of chemicals in some plants that inhibit growth in competing plants nearby. This article from Cornell University includes this statement:

"One of the most famous allelopathic plants is Black Walnut (Juglans nigra).  The chemical responsible for the toxicity in Black Walnut is Juglone (5 hydroxy-1,4 napthoquinone) and is a respiration inhibitor.  Solanaceous plants, such as tomato, pepper, and eggplant, are especially susceptible to Juglone.  These plants, when exposed to the allelotoxin, exhibit symptoms such as wilting, chlorosis (foliar yellowing), and eventually death.  Other plants may also exhibit varying degrees of susceptibility and some have no noticeable effects at all.  Some plants that have been observed to be tolerant of Juglone include lima bean, beets, carrot, corn, cherry, black raspberry, catalpa, Virginia creeper, violets, and many others."

Black walnut isn't the only tree that produces juglone. This chemical is also secreted in smaller amounts by English walnut, hickory and pecan trees.Other trees with allelopathic properties include tree-of-heaven, sugar maple, hackberry, American sycamore, American elm, southern wax myrtle, cottonwood, black cherry, sassafras, red oak and black locust.

So, we know about Black Walnut not being a threat to your corn, now to find out if Celtis laevigata (Sugar hackberry), which is a member of the Ulmaceae (elm) family, could exibit allelopathy. We found this list of pests in corn:

Frankly, we think any of them would be worse than a nearby hackberry. Since the center of origin of  Zea mays (corn) is believed to be native to Mexico or Central America, we don't know  too much about it. If your (native) hackberry is shading the corn, you might want to think about it, but otherwise, we feel the corn is safe.


From the Image Gallery

Sugar hackberry
Celtis laevigata

More Trees Questions

Disease or insect damage on a Mexican plum
September 08, 2013 - Help, Our Mexican plum tree is about 13-14 years old. Earlier this year we noticed the trunk is oozing black stuff and whole branches are dying off. We have watched as our beloved tree has lost most ...
view the full question and answer

Need suggestions for plants for a privacy screen in Long Beach, NY.
August 10, 2011 - I have recently added 1500sq.ft. to my backyard. My backyard faces a busy road. I would like to place native trees and bushes along the fence for added privacy, shade and to protect my house from the...
view the full question and answer

Native Perennials for Bees and Butterflies in VA
April 15, 2015 - What native perennial plants and trees can we plant to help honey bees and butterfly larvae in Harrisonburg, VA?
view the full question and answer

Trees & Shrubs for a NY Slope
July 03, 2012 - Our community has a large steep slope (100'high by at least 600' wide) that is sunny & dry. The builders planted "wild flower seeds" on the slope that is now just weeds. We would like to know what...
view the full question and answer

Viability of Desert Willow in clay soil in Fredericksburg, TX
November 25, 2005 - I have recently purchased a house in a new subdivision in Fredericksburg, TX. The lot was not landscaped. I have a small lot (85 X 135), my back yard is about 50 X 85. The soil is a heavy clay. I am c...
view the full question and answer

Support the Wildflower Center by Donating Online or Becoming a Member today.
© 2015 Lady Bird Johnson Wildflower Center