Slimwhitman, if no one else chimes in I will say my "big" metasequoia has been in the ground eight years about a hundred yards from any of my walnuts.

I have an "Ogon" in thr ground two or three years now about thirty yards away. That yellow needled thing is growing FAST.

My soil is clay, my yars is sloped. Between my and my neighbirs we own a dozen or more black walnuts mostly stradling our property li es.

I do not recall ever seeing specimens of these two trees growing close together in the wild. I have canoed, floated, or walked down many of the streams/rivers of central Texas and a few in north La.

Walnuts release natural weed killers this is called Allelopathy but the trees that you talk about should be too far away to be affected. Can we see some pictures of the trees and of how they were planted?

Someone else stated the distant location. My original quetion was about new blad cypress planted under or very near walnuts. I know the walnuts release this toxin, but not all plants are affected by it. I am wondering if bald cypress or dawn redwood are specifically affected by walnuts.

I found a list from Michigan St. University's horticultural department of plants/trees that are and aren't sensitive to juglone and neither baldcypress nor dawn redwood are on either list. Maybe Dan will know.

Here is a link that might be useful: Black Walnut Toxicity

I just lost a dawn redwood from what I believe was the juglone toxins.. I moved the tree into its location in the beginning of the spring, and a few weeks ago it basically died. It was planted 25 feet away from the main trunk of a 40 year old black walnut tree. I believe that the walnut is what killed the redwood, I can't think of anything else it could have been. I am not really sure what is killing yours, maybe post a picture so we can see just how close they are.. If it directly under the tree, I feel like its the juglone..

J

taxo.. i dont understand..

you dig a receiving hole.. presumably remove all the soil.. and move a balled tree into the hole... and it dies a few months later..

how did the walnuts toxicity get in the hole????

i am not saying you are wrong.. but based on only what you say... how did you jump to that conclusion .... you are a much better plantsman than me.. if you rule out transplant problems .. ahead of everything else ... or there are a whole bunch of facts about the job that you have left out .. was there enough sun 25 feet from a 40 year old tree??

ken

An update:
I went back the the area to re-evaluate the problem areas. We actually have several walnut trees on the perimeter of the bald cypress grove we are trying to establish. There are several on the north side, one on the south side and a couple on the east side. In all cases, most of the bald cypress/dawn redwood whips and B&B trees have died under those walnut trees. Almost all other B.C./D.R. have lived in other areas not directly next to/under the walnut trees.
The death sometimes takes a few years. It seems clear to me that the walnuts are the problem. I just wanted to verify that with some study that may have been completed and published somewhere, but there seems to be nothing documented on the subject.