fruit tree (peach) that did have wonderful peaches then developed a fungus ( I guess).
Hi- the growth on the branch are lichens. Harmless to the tree. They indicate that that portion o the branch is largely shaded.
It's hard to tell from the photos but we suspect the fungus that developed on your peaches is brown rot- a widespread disease of stone fruits that makes growing stone fruit a challenge for Maryland gardeners and commercial growers. Sanitation and properly timed fungicide sprays help to combat the disease. The fungus overwinters in twig cankers and in mummified fruit that is left hanging on the tree or has dropped to the ground. So, pick off and dispose of infected fruit (and fruit stems) from the tree and rake up any that has fallen around the tree.
Next year, apply labeled fungicides when the blooms are between 5-10% open, at full bloom, and about 2 weeks prior to harvest. It is best to apply fungicides before a rain event is predicted instead of waiting until after. Additional cover sprays will be necessary if we are experiencing a cool, wet spring and summer. Rotating fungicides helps to reduce the fungus from becoming resistant to the preventative sprays.
Fungicides available to home gardeners can prevent but not cure infections. Organic fungicides like sulfur can be somewhat effective but may damage new spring growth. Immunox, captan, and Bonide’s Fruit Tree and Plant Guard are the three available synthetic fungicides.
More brown rot information:
VA Tech fruit pest guide and spray schedule: