The “witches’ broom” growth characteristics are even more pronounced in this picture. The repeated leaf and twig infection causes them to drop from the tree. When this is repeated year after year, this causes severe growth deformity. The tree needs to rid itself of this repeated infection, but needs help to do it. Over a few years of proper treatment and fertilization, sycamore trees can recover from this disease. The key is to catch it before the decline gets too bad.