I lost a Bradford Pear tree last year. I planted it in the back corner of my yard about 7 years ago and it appeared to be thriving well until late last spring. After blooming nicely and putting on leaves, the leaves turned brown as the summer heat came on. they later fell off and the tree produced some buds. I read Howard's sick tree recipe and promptly went out and purchased the ingredients. I applied green sand, lava sand, dried molassis, and horticultural cornmeal. I removed the dirt around the base of the tree to expose the flare, applied the treatment and covered with cedar mulch. Nothing ever happened and the buds never opened and are still there. Now the adjacent plants (redtips) have the purple spots and the leaves are turning yellow and falling off.

The area where they are planted is pretty poor with hard clay about 6 inches down. Seven years ago when I created the bed, I tilled to about 1 foot and added a lot of gypsum and other materials. The reason for the poor soil is that the lot was graded out of a hill for my development. Just behind the bed is a 4 foot railroad tie retaining wall and my neighbor has a swimming pool on the lot above it.

Did my sick tree treatment kill the pear and now the redtips?

From the info you supplied, it does seem like you killed your trees. The sick tree treatment was not the cause. When you tilled the area and added the amendments, you created a "pot" or "bowl" effect that the roots probably stayed in. In other words, the roots didn't go down into the ground but kept circling in the amended area. You could dig down in the area and verify this. Read the planting instructions below:

http://www.dirtdoctor.com/view_question.php?id=56

_________________
The "soap" you use is normally chemicals, etc. Use real SOAP !!