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["Alan Haigh" <alandhaigh@gmail.com>]

I manage an orchard which is adjacent to 2 very old northern hardy pecans.  The soil is shallow and at the orchards closest proximity to these pecans there are a group of peach trees which have failed to grow well at all.  I notice that the pecan roots look and smell very similarly to black-walnut roots and have come to the conclusion that they may well be the cause of this faulty performance.

 

When I first arrived at this site years ago, I was asked to replace peach trees that had died in this spot.  I broke up a considerable amount of soil, severing competing roots some distance from the trees and these trees grew as vigorously for 2 or 3 years but than began to runt out.

 

I was unfamiliar with pecan trees so it was a while before I identified them (noticed very small pecans at their base).  Once I decided that my problem could be alleopathy I took a metal spade with a long handle and long blade (King of Spades) and trenched a couple of feet down in about 8' diameter circles around each peach tree.  After this the trees became vigorous again for a year but runted out later and didn't respond the next time to this treatment.  My theory is that the roots of the pecans are now well established beneath the depth I am reaching.  To go still deeper is not practical.

 

My question to you out there with more experience with pecans is whether you've had similar difficulties growing peaches under them.  Other trees in the orchard, even apricots and cherries just as close, have not suffered to the same degree (if at all).  Am I even correct that Carya sp. have the same alleopathic tendency as Juglans?  My google search seems to indicate that to be so but I was unable to find specifics before running out of patience.

 

I also have had the same problem with brambles on the same general site where there is another very large pecan nearby and black pecan roots visible where the berries are planted.