From your description I would agree that it is more of a competition problem. Al

hman,
I've always wondered how much of the 'juglone' effect was merely due to things being planted in the root zone of a large, overtopping tree that was well-established and able to out-compete smaller newcomers for available moisture, nutrients, and sunlight.
Growing up in the Southern pecan belt, I've seen and grown azaleas/rhododendrons beneath large old (100 yrs) pecans, with no noticeable stunting - and they're one of the species on the 'juglone impact' lists I've seen, so at least based on my experience, I'm inclined to believe that pecans/hickories don't produce sufficient juglone to have significant impact..

For the pecans it has to be competition, I saw a paper maybe two months ago that showed that the root/aerial mass ratio depends strongly on the level of competition.

For the walnut, it is juglone. I have a large one myself, and I have a friend who planted a small orchard within 80 ft of a BW (despite my repeated discouragement). So he planted every vigorous near (about 50-60 ft) the tree, and everything small (dwarf apples) as far away as possible. Now he has the dwarf trees which are the tallest in the orchard, and the first line of trees looks puny and I do know how it is going to end. My own BW has one root that has traveled a good 70 ft from the trunk. Who knows how far the finer roots go.

My point is that BW has the same kind of competitive root system as the pecans, they even look physically the same and if the pecans are stunting trees without juglone why would the stunting affect of the BW roots not be brought about by both poison and competition? The peaches under the pecans are as stunted as any I've seen in spite of generous mulching and a very good, extremely well drained and more than adequately deep soil. Also ample N. and water.

My experience has been different here. Seven or 8 years ago I planted a peach tree within 80' of the trunk of a large BW that is old enough to be in decline not knowing about the Juglone issue. The peach tree has thrived and turned into a very productive tree, go figure.

Michael, was there a thick mat of tough black roots throughout the soil when you planted it?

Harvestman BW nuts that decay on ground what does damage in shuck's of nuts. You put six fresh walnut around tree trunk let decay that tree goner or screw up. What did to my pecan tree made have 2 shells one inside other then nut meat half's.

Gator, I don't know what part of the tree has most concentrated juglone. The little I've read suggests all parts of the tree contain it but the roots are a constant source of juglone and I gather, the largest problem.

H-man: I really don't remember anything about a mat of roots of any sort nor do I recall having any trouble digging the hole to plant in. My red raspberry row ends aren't more than another 10 feet away from the walnut than the peach tree and they have also been doing very well for the last 5 years +-.

That walnut tree sure feels good buning in my wood stove right now :) thanks neighbors!

I wasn't going to comment but I'm bored.
My wife has an evergreen patch. so far 5 white pines and 2 blue spruce.

Everything has done fine with one exception. We planted 2 identical blue spruce. One at one end and one at the other. They were about 2ft tall. The one farthest from the walnut is about 7-8 foot tall. The other that is about 25ft from the BW is about 3 ft tall and losing it's botton branches.

My wife doesn't like it and is going to make me remove it.

It may be a coincedence.. that's why I did not want to say anything.

Something that comes to mind is that HM may have a low juglone genetic variation. Walnuts do exhibit a good amount of genetic variation. I have a friend who has a walnut growing on his property in Northern Michigan, a place that has, over the last 150 yrs, experienced at least one killing frost every month of the year. Walnuts are not supposed to grow there. Both he and HM may have something Cornell Univ. may be interested in.