En EspaŅol
Share

Ask Mr. Smarty Plants

Mr. Smarty Plants - Are hackberries harmful to other trees?

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

Wednesday - March 25, 2009

From: Austin, TX
Region: Southwest
Topic: Trees
Title: Are hackberries harmful to other trees?
Answered by: Joe Marcus

QUESTION:

A neighbor warned me that a hackberry tree that naturally sprouted up recently will harm the roots of other trees nearby and that it is such a bad tree we should take it down before it gets too big. It is surrounded by mostly cedars and an oak. Do you thinks hackberries can do harm and are worthy of removing for that reason?

ANSWER:

Every plant that puts down roots in the earth compete in some way with its neighbors; some compete more aggressively than others.  The rhizosphere, that is, the soil where roots grow, can be thought of quite accurately (if not a bit simplistically) as a war zone.  Plants, animals, fungi and microorganisms living within the rhizosphere continually struggle with one another for their share of the resources available there.

Many trees and other plants interfere with their competition through one of a multitude of processes known collectively as allelopathy.  Allelopathy typically involves living or dead and decaying plant parts exuding, volatilizing or leaching chemical compounds that are inhibitory or harmful to nearby plants.

Hackberry trees, Celtis spp. are known to inhibit the growth of competing plants through allelopathic processes.  The mechanism used by hackberries involves the release of a witch's brew of chemicals known as phenolic phytotoxins leaching from fallen, decaying leaves.  The leachates from rotting hackberry leaves have been shown to inhibit the germination of seeds and the development of seedlings.  So yes, hackberry can do harm to nearby plants, though it is unclear if it has any effect at all on established plants such as trees, shrubs or even mature perennials. 

Ashe juniper, which is probably the cedar your mentioned in your question, and oaks are also known to be allelopathic.  Few plant species will thrive beneath the canopy of Ashe juniper.  If there are any sycamores, pecans or walnuts in your garden, they're also waging chemical warfare on one another.  Lest you come to think of these trees as "bad plants," you should know that as time goes on we will certainly come to learn that many, if not all, plants employ chemical defenses (and offenses) in one form or another.

As landscape plants, hackberries are not without other problems.  They're messier than most other trees, tend to be short-lived, are prone to breaking in storms and don't often make particularly handsome specimens.  On the other hand, hackberries are extremely important sources of food for wildlife.  Many birds, mammals and some butterflies depend on hackberries for their survival.

On balance. hackberries definitely play an important role and have a place in nature and maybe even in peripheral areas of your landscape.  They are probably best left out of more prominent parts of your garden, though.

 

 

More Trees Questions

Sticky sap (honeydew) on car
July 10, 2012 - MY CAR IS CONSTANTLY COVERED WITH STICKY SAP. I LIVE IN AN AREA WITH MANY COCONUT PALMS AND OTHER TREES. COULD THE SAP BLOW AROUND EVEN THOUGH I KEEP CHANGING THE PARKING?
view the full question and answer

Distinguishing elm species from volunteers in yard
April 10, 2008 - What's the best way to distinguish young elm tree species apart from one another? We have a bunch coming up in our yard and we're trying to figure out if they are Winged, Cedar or American. Some of ...
view the full question and answer

What is causing leaf drop on oak in Morgan Hill CA?
June 23, 2010 - Dear Mr Smarty Plants: We have a large, young Valley Oak (about 20 yrs) which is dropping leaves even now in early summer. I have a feeling that the problem might be an invasive weed that is flourishi...
view the full question and answer

Treating suspected drought-stressed live oak
July 13, 2011 - I have a live oak with excessive leaf drop - it was planted approx. 20 year ago surrounded by heavy pavers. very little grass - I did not plant the tree - I have noticed in the last few years the dro...
view the full question and answer

Failure to thrive of Eastern Redbud in Dearborn, MI
May 26, 2009 - Our Eastern Redbud, multi-stem tree has done well for several years. This year the pods did not fall off, the tree looks anemic, lots of dead stems, no pink blooms this spring. What can we do??
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
© 2014 Lady Bird Johnson Wildflower Center