Q.Problem With Pink Double Knockout Tree
I put in 6 pink double knockout rose trees three years ago and they have been beautiful. This year, all are coming out except one. Its new growth foliage is shriveled and not growing. The remaining plants seem fine. I have fertilized and added iron but nothing seems to help. I cannot find anyone who knows what is happening to the plant. Any ideas?

It sounds like it may either have a virus of some sort or something either got sprayed upon the foliage or somehow poured onto the soils around the tree rose. There are some viruses that will cause this sort of thing and unfortunately there is no know cure. If it does not snap out of it soon, I would dig it out along with all the soils in a 20 inch diameter circle around it. Replace the soils with good amended soils and plant a new tree rose. It is sometimes best to get rid of the rose tree effected as soon as possible so as not to risk speading of the problem to the others.