Ask-a-Dave's-Gardener: Dying apple tree , 4 by alcina

alcina wrote:
My little Golden Russet has been struggling since I put it in the ground last fall. It was bare root planted into a mound of amended soil. The area I planted into has a lot of clay, but we spent the prior year filling deep garbage pits and otherwise amending with organic matter. This spring, the tree leafed out nicely and then immediately showed signs of what looked like rust. As my other apple -- a Crimson Topaz -- was also showing signs, I removed the infected leaves and treated the trees with Serenade. The Crimson Topaz has done fine, but the Russet has gone through phases of rallying and waning. The CT, however, is planted in a different area -- so different soil. This past week, the Russet has taken a very bad turn. It\'s been suggested that the tree is sitting in perched water, and so I planned to move it. However, with the recent changes, I\'m wondering if the problem is something worse. The new leaves are frequently yellow, older leaves develop spots and then yellow, and last week dark olive-coloured areas have appeared and are spreading through the entire leaf. The leaves, however, are not dried out, but rather feel like thin leather. Any ideas what it could be? And is it worth digging it up and moving it to try to save it? Thank you.
(Originally posted in the Fruit & Nut forum with no luck.)