Jupiter Apple Tree Fungus Identification and Erradication

I have a Jupiter Apple tree the I have trained into an espalier over the last 8 years or so. It has never produced more than a couple of apples and in the last two years has been suffering from this white fluffy disease that I cannot identify. I have asked for help before and was told to winterwash which I did this winter but the fungus has come back even more vigorous than ever.

Can you help identify what this disease is and how I can erradicate it and hopefully actually get some fruit.

Thnajs Everyone