I have several fruit trees (Apple, Cherry, and Peach) that all have an identical growth on the bark. It looks like a fungus to me, but I'm uncertain of the exact identification and what to use to treat it. Could someone identify this and offer a recommendation for treatment?
That is lichen, which is not detrimental to your tree's health (it's not a parasite, it lives off of photosynthesis). This is normal, no need to worry.
Yes, It is a lichen. It belongs to Parmeliaceae family. The picture is of poor quality, but it could be Parmelia saxatilis if there are some isidias, or Parmelia sulcata if there are some soralias (on the thallus).
Lichens are not a problem for your trees, they are in fact constituted of a symbiotic association between a fungus and a photosynthetic algae (it is the mushroom that invented agriculture!).
Some species are valuable to assess the air quality. Generaly yellow species indicates poor quality and air pollution...
Cheers,
R.
