Plants can DO this?!

Yes, Cheryl, they sure do.

A classic example of this is the Black Walnut tree. Usually nothing will grow in a wide perimeter near its roots.

Here is some rather interesting reading about the phenomenon:

http://www.forestry.uga.edu/ou...

That is very interesting, Janice. Thank you for posting your idea for me to learn from.

My pleasure, Cheryl!

This is a little trick that alfalfa does, too, except that it only affects other alfalfa seeds. It's also called autotoxicity in alfalfa. So if you have an alfalfa field that is getting old, you can't just throw out new seed. You have to till the old plants under and plant something else until the effect dissipates. One of the joys of *trying* to grow alfalfa!

Thanks, Woofie! Interesting!
How long to wait to plant another Alfalfa crop?

found this:
http://www.americasalfalfa.com...

and
http://www.extension.purdue.ed...

In our area, the neighbors I know who have replanted alfalfa just waited about a year before sowing new seed.

The squirrels keep "planting" black walnuts directly next to our property. The are 2 trees (2 that I know of, hopefully not more).

The allelopathic properties of Black Walnut trees are often exaggerated. I grow plants of dozens of genera in close proximity to a huge tree. I won't list them here, but they are listed in the first few posts of this thread, grouped according to their distance from the trunk, in the Juglone Cubit.

http://cubits.org/juglone/thre...

woofie said:In our area, the neighbors I know who have replanted alfalfa just waited about a year before sowing new seed.

Thank you, Woofie!

Those darned squirrels, Marilyn......

Thank you, Zuzu, for the link! What a wonderful thread with such useful information!

It's good to hear that the tree is not universally problematic!

zuzu said:The allelopathic properties of Black Walnut trees are often exaggerated.

My thoughts exactly... There are a lot of people being scared off from growing a beautiful native tree as a result of the hype.

Maybe people oughta discuss the allelopathic properties of cogon grass instead...

It is a beautiful native tree, Stone. I agree.

Allelopathy need not be seen as a negative thing.
More it is a coping mechanism for the organism to protect its turf and resources for its own survival.

As in Zuzu's thread, many plants grow well near Walnut trees.

It's true with black oil sunflowers, too. Anything we planted beneath the bird feeder died. The weeds, however, seem to have developed a tolerance to it...

Amazing those weeds ,huh, Renee?

If only perennials had the gene pool of weeds, they'd REALLY be perennials,.... capable of leaping tall buildings in a single bound!!!

And landing on top of that building and taking root and taking over the world!!!! (too much SF at a tender age... )

http://www.permies.com/t/5151/... There is a list in this forum at Permies.com of plants that grow under/near black walnuts. There is another permaculture model in Toby Hemenway's Gaia's Garden.

Thanks for the great links, Hazelnut!

A wealth of useful and interesting information there!

The stump of a black walnut tree that I cut down (shouldn't have) is now colonized by sand pears. Sand pears are sometimes used to graft roots of nursery-grown regular pears. My neighbor cut down his pear tree and left the root, which seeds like crazy all over the place. Its not malus, but I think this means pears don't mind growing around black walnuts.

Does anyone know if the Aegopodium, Bishop's Weed has allelopathic properties? I thought I read that somewhere long ago. It is a highly invasive groundcover, sometimes variegated, sometimes all green, seldom welcome.