Persimmon trunk damage

Coralie Endean starts with ...
Hi again guys!
I was wondering if you could help me with a diagnosis of what is wrong with my persimmons. They are about 4-5 years old and have cropped heavily this year and were netted until 2 months ago (see fig1). Recently they have started to colour and loose their leaves. However, one persimmon didn’t colour, rather the leaves died and fell off! On close examination there are blisters along the trunk, which at some points exude gum (see fig 3). What is happening? Is this a borer? (I cant see any holes) or is this phytophora or some other sort of fungal disease? It appears to be spreading to the adjacent tree (see Fig 2 – The sick one is far right). How do I fix it?
Hope you can help
Coralie

Pictures - Click to enlarge
Picture: 1	Picture: 2	Picture: 3

Coralie says...
Hi again, We do have hare damage (to far north for rabbits) on some of our fruit trees in winter that are outside the dog fence. I dont think this is either rats or hares because it comes up in a blister first before breaking out into weeping sap. Probabily the picture I sent was deceiving.
Coralie