The discoloration of this aspen and the bright orange tendrils are caused by the fungal disease Cytospora. There is no effective treatment for Cytospora, the focus should be on prevention and keeping the tree as healthy as possible. Cytospora affects a variety of trees, including spruce.
Fire Blight is a bacterial disease primarily of apple, crabapple, pear, mountain ash and hawthorn trees. It gets its name from the scorched appearance of affected leaves, not to mention how fast it spreads. Treatments are available but they are not a cure-all.