Allelopathy in Tung Oil Tree (Vernicia fordii)

[_Keith]

This tree is fabulous in spring, but my nearby W. filibusta is all but dead for no apparent reason. A Magnolia 'Little Gem' nearby is also faltering. The Tung Oil is healthy as a horse. I keep wanting to suspect Allelopathy, but am not finding any references to back that up. I know we have some true experts here on the forum, and lots of very educated amateurs as well. What do you think? Possible, probable, or am I barking up the wrong tree, lol?

[The Silent Seed]

I would only assume - since the leaves and fruits that fall onto the ground are equally poisonous - I can easily see those chemicals building up in the soil around the other trees. Very cool observation though!

[Bennz]

I was waiting for an expert to comment before I made any remarks.

My understanding of alleopathy is it usually is related to inhibiting germination of competition, rather than killing established plants. I don't know this tree and have no experience with it. It seems unlikley to me that in its habitat there would be no other plants in its vicinity at all, which would need to be the case if your suspicions are correct.

I grow some alleopathic Eucalyptus trees here. They start as benign seedlings, then as they establish they start preventing competitors germinating through alleopathy, then finally start killing competing vegetation through competition for water and nutrients. Could this be the same pattern with your tree?

I guess you needed to tell us how old the three trees are. I'm assuming you have not recently planted the Washie and Magnolia?

[The Silent Seed]

Just to clarify; competition is not allelopathy. It makes for some very interesting reading for sure.

If your Eucalypts are basically hoarding nutrients, etc - that is competition, not what is called negative allelopathy.

If a plant is releasing toxins, chemicals, such as presented here, or another common tree named the Black Walnut, it will suppress, inhibit, and kill surrounding plants, which is called negative allelopathy, as opposed to positive allelopathy, where a plant is encouraging other species to grow, for any given reason, to benefit it.

If the "other" plants were present before; and the allelopathic started life in that area later, then as it grows, it would have the same impact as if there was already an established plant there, preventing newly planted plants from growing.

Hope that clears it up.

Edited December 31, 2014 by santoury

[Bennz]

Just to clarify; competition is not allelopathy. It makes for some very interesting reading for sure.

If your Eucalypts are basically hoarding nutrients, etc - that is competition, not what is called negative allelopathy.

If a plant is releasing toxins, chemicals, such as presented here, or another common tree named the Black Walnut, it will suppress, inhibit, and kill surrounding plants, which is called negative allelopathy, as opposed to positive allelopathy, where a plant is encouraging other species to grow, for any given reason, to benefit it.

If the "other" plants were present before; and the allelopathic started life in that area later, then as it grows, it would have the same impact as if there was already an established plant there, preventing newly planted plants from growing.

Hope that clears it up.

I think we are saying the same thing, but I'm not 100% sure. In my example, Eucs seedlings establish with no impact to surrounding vegetation, but as time moves on their alleopathic properties prevent germination of other seedlings, while at the same time their vigorous roots compete with existing plants for moisture and nutrients. So the alleopathy is stopping germination, the competition is with already established plants.

Taking the black walnut example, I would say a black walnut seedling establishing in a palm grove would not cause much problem to the existing palms, but would cause problems to palm seeds that might otherwise have germinated in the stand. I suspect the competition from black walnut would be less than from a euc, buit could be wrong. Certainly I have 30+ year old black walnut trees here that still have good grass growth under them.

SO back to Keiths problem. If the washie and magnolia were planted under the tung then alleopathy might be the issue (if the tree actually is alleopathic!), but if they are similar age or older I would suspect something else. I doubt competition would impact a Washie much, from what I've seen in NZ. Magnolias certainly get restricted by competition though.

[Alicehunter2000]

There is a Tung Oil tree behind one of my stores....the woman there grows lots of things in her yard....never noticed that plants were struggling nearby....would have to check to make positively sure.

You would think....just from the nature of the chemicals in the tree that it would have some degree of allelopathy

[_Keith]

By total chance, in another gardening book, I may have found my answer. Apparently the fruit dropping from the Tung Oil fruit allowed to build up can bind up the Magnesium in the soil to where it is unavailable.

[trioderob]

tung oil makes a wonderful finish for pine- makes it a real pretty golden color