I have an apple tree with this disease (see photos). Not sure exactly what the disease is - some kind of leaf spot. Initially I had tried removing leaves and intermittent spraying with copper, then later with natria, but the disease spread and is pretty much through the entire tree. There are some new leaves at the top that look healthy. Pruning off diseased branches/leaves doesn't seem like a viable option since it's pretty much the entire tree.

What is the recommended approach?

If removing severely affected leaves and branches is still recommended, how much is too much?

Should I just wait for next season?

What treatment is recommended?

Thank you

Do you have cedar trees around? Looks like rust or it could be a blight of sorts. Best bet is to contact your State Extension service for help since they will know what is affecting apple trees in your state the best.

It's Apple scab.
What you should do no is rake all the leaves that fall and burn or compost them after adding lime. You may want to fertilize with urea and zinc to encourage leaf drop: the spores overwinter on the leaves, alive or dead, so they must be disposed of.

The spores are dispersed by wind and fungal growth is encouraged by high moisture: for next year plan to protect the tree from overhead irrigation if you have any.
Since you now know Apple scab is in your area, next year as soon as the leaft tips emerge spray the tree with a copper based fungicide. If the season is wet you may consider using a captan or tebuconazole fungicide to protect the tree, but remember fungicides must be applied at the onset of wet weather and are preventive, not curative.

ElPolloDiablo said: It's Apple scab.
What you should do no is rake all the leaves that fall and burn or compost them after adding lime. You may want to fertilize with urea and zinc to encourage leaf drop: the spores overwinter on the leaves, alive or dead, so they must be disposed of.

The spores are dispersed by wind and fungal growth is encouraged by high moisture: for next year plan to protect the tree from overhead irrigation if you have any.
Since you now know Apple scab is in your area, next year as soon as the leaft tips emerge spray the tree with a copper based fungicide. If the season is wet you may consider using a captan or tebuconazole fungicide to protect the tree, but remember fungicides must be applied at the onset of wet weather and are preventive, not curative.

It's not a huge tree, should I manually remove all the leaves? I was concerned that may risk it's health. Or should I wait until the winter?

Most fungicides that work for apple scab are preventative not curative. They must be applied prior to infection to prevent the scab spores from germinating on the leaf or fruit. Captan and Rally are two that work well. Rally, Eagle and Immunox are all brands that contain the same active ingredient (myclobutanil).

grillmaster513 said: It's not a huge tree, should I manually remove all the leaves? I was concerned that may risk it's health. Or should I wait until the winter?

As said to speed up leaf drop fertilize with urea and zinc. Foliar sprays act faster, just don't buy gallons of them to avoid wasting money.

Scab doesn't kill apple trees: it weakens them, meaning next season they may produce fewer/smaller apples, and much more critically spoils the fruits. For farmers scab apples are unsellable and don't expect them to be palatable.