Years ago, in Iowa, I had a Black Walnut in my yard- the only problem I had was growing Tomatoes (it was rather near my garden). We went out of town for a week and remarkably, the tree was cut down and stolen while we were away!
Since I detest eating Black Walnuts and it was ugly tree, I was (secretly) pleased the thieves stole it. I planted a Weeping Willow very near the stump and it grew just fine. As for residual effects- none were noted. In fact, my tomatoes the following year were almost perfect. btw... about 40 or so feet away, there was a Red Spire Pear (another clone of P. Caleryana ). It seems to do just fine.
Perhaps there is some genetic difference between trees as to how much juglone is produced by any individual.
