Does a Black Walnut Tree poison the soil?

[ChickenLady]

I've heard you can't grow tomatoes within 30 feet of a black walnut tree. We planted blueberry plants about 20 feet from one and they just didn't grow. I have two Pecan trees I'd like to plant on the same side of the house as the Black Walnut, but I don't want to lose them. Am I safe to plant them near this tree? If so, how far away from the Black Walnut should I plant the other trees?

 

[KenJax Tree]

Its true they produce a chemical called Juglone and plants such as tomatos and blueberries are sensitive to it. The Pecan trees should be ok because they themselves produce Juglone just not as highly concentrated as Black Walnut. Sensitive plants should not be plants within 50-60ft. of a large Walnut tree.

 

[isaaccarlson]

Some fruit trees can grow near walnut, but we found out the hard way that pears are not one of them. Our plum trees seem to love walnut.
Do some google searching and you can find lists of the plants that react to walnut.

 

[Toronado3800]

You can google walnut toxicity and get as good a guesses as anything. I have a row of a dozen or so in a wild grove on a hill. Ash, redbud, elderberry, honeysuckle(yuck!), every vine imaginable, Peach, silver maple and cherry trees are all growing near them. There is bound to be some formula with soil drainage vs this or that. But yes, they are nit friendly competitors!

 

[ChickenLady]

Thank you- Comments Most helpful!

I've heard you can't grow tomatoes within 30 feet of a black walnut tree. We planted blueberry plants about 20 feet from one and they just didn't grow. I have two Pecan trees I'd like to plant on the same side of the house as the Black Walnut, but I don't want to lose them. Am I safe to plant them near this tree? If so, how far away from the Black Walnut should I plant the other trees?

I have read the comments thus far and they are all helpful. I am so glad I found this site and am sure to keep it handy for the future. Thank you so much.

 

[Don McKell]

We had a mature walnut tree at the rear of our house that had begun losing about 1/3 of its previous year's foliage for each of the past few years. It was being attacked by termites and other insects, plus it was at least 50 years old, so we decided to remove it in hopes of planting another species tree in its place. I had the stump ground to a depth of about 25", and then strained all of the loose soil dug up by the stump grinder through a 1/2" wire mesh screen in order to remove residual root parts and stones. I have piled that strained dirt in a separate place until I can figure out whether it's safe to re-use.

My plan was to enrich that dirt with an equal volume of clean topsoil or mushroom compost and then return it to the hole from which it came. Afterwards, I hope to obtain a crepe myrtle in a 24" box and plant it in the exact spot from which the walnut tree was removed.

My questions:

1. For what length of time do you believe the levels of juglone in this soil mixture might have adverse effects on plantings placed in it?

2. In your opinion, is crepe myrtle a tree (shrub) that is resistant to juglone in any substantial way?

Thank you so much for your time and expertise.

Don McKell

Los Gatos, CA (Zone 16)

 

[Mad Professor]

We had a mature walnut tree at the rear of our house that had begun losing about 1/3 of its previous year's foliage for each of the past few years. It was being attacked by termites and other insects, plus it was at least 50 years old, so we decided to remove it in hopes of planting another species tree in its place. I had the stump ground to a depth of about 25", and then strained all of the loose soil dug up by the stump grinder through a 1/2" wire mesh screen in order to remove residual root parts and stones. I have piled that strained dirt in a separate place until I can figure out whether it's safe to re-use.

My plan was to enrich that dirt with an equal volume of clean topsoil or mushroom compost and then return it to the hole from which it came. Afterwards, I hope to obtain a crepe myrtle in a 24" box and plant it in the exact spot from which the walnut tree was removed.

My questions:

1. For what length of time do you believe the levels of juglone in this soil mixture might have adverse effects on plantings placed in it?

2. In your opinion, is crepe myrtle a tree (shrub) that is resistant to juglone in any substantial way?

Thank you so much for your time and expertise.

Don McKell

Los Gatos, CA (Zone 16)

Test the soil by trying to grow a tomato plant in it.

I was worried one year when I mulched my tomato plants with leaf compost that had some butternut leaves in it (walnut relative), it was rotted from the previous year and the tomatoes did fine.

 

[ropensaddle]

This is my hunch, eleochemical Juglone "is I believe" put off by the living organism not the dead decaying. It's my guess after the decay process starts little to no Juglone remains but this is as I've stated a guess. Hopefully someone else may chime in with more understanding of the process.