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Friday - May 21, 2010

From: Austin, TX
Region: Southwest
Topic: Trees
Title: Is Black Cherry allelopathic from Austin
Answered by: Barbara Medford

QUESTION:

Is the Black Cherry an appropriate tree to plant in north Austin as a shade tree? Your site says this tree may be allelopathic to garden plants . Do you know specifically which plants it might help or hinder? Thanks.

ANSWER:

There are five members of the Prunus genus with the words "black cherry" as part of their common names and are also native to Texas. They are Prunus serotina (black cherry), Prunus serotina var. eximia (black cherry), Prunus serotina var. rufula (black cherry), Prunus serotina var. serotina (black cherry) and Prunus serotina var. virens (black cherry). Of these, 2 are native to Travis County: Prunus serotina (black cherry) and Prunus serotina var. eximia (black cherry).

We found the reference to allelopathy that you mentioned on the webpage in our Native Plant Database for Prunus serotina (black cherry):

"The plant drops lots of twigs, leaves, and fruit, and in cultivation can be allelopathic to garden plants."

All members of the genus Prunus have poisonous parts. In fact, the only parts not poisonous are the skin and the fruit. The seeds are extremely poisonous, and the leaves, especially shriveled leaves, as well as twigs, branches and roots are poisonous. If soil beneath a plant is covered with litter that is toxic in nature, that is going to be a big barrier to the germination or flourishing of anything else.

Different plants have different chemicals which cause their allelopathy. With the black cherry, it's a substance called amygdalin. The black walnut has juglones, the magnolia sesquiterpene lactones. The acidity in pine needles causes acidity in the soils which can be damaging to plants. To our knowledge, there are no studies presently available on what plants would be resistant to these allelopathic agents, regardless of what chemical is involved. If you had something you really wanted to plant beneath a Black Cherry, about your best defense would be to keep the ground beneath it thoroughly raked, removing and disposing of any litter as quickly as it appeared.

For many years, we gardened with volunteer (probably brought to us by birds) Prunus caroliniana (Carolina laurelcherry). This was long before we had ever heard of allelopathy, and had a lot of native Quercus stellata (post oak), also suspected of emitting substances to keep competitors from coming up. It was difficult to grow anything in that yard, and we always thought it was just the shade from the oaks. This article from Floridata, Prunus serotina, says that most people acquire the tree as we did, by bird delivery, and it is not widely available in the nursery trade. It can grow from 40 to 60 ft. tall in cultivation, and is said to be fast-growing.

Your question was whether this plant would be appropriate. That is a decision only you can make; if you are determined to have flower beds beneath the tree or if you have small children or pets that might eat some of the fallen material, it is probably not appropriate.

From our Native Plant Image Gallery:

Prunus serotina