peach and nectarine tree top disease

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I bought and planted 3 fruit trees 2 nectarine and one peach almost 2 years ago. Entire time that they have been in leaf they have seemed to have had a disease at the tip where the fresh growth is. It sometimes has a jelly clear sap clear to amber like substance as part of the diseased area. There was one piece of fruit this year and it also had this clear jelly-like SAP on the side of the fruit. Can anybody tell me what this is and how I might treated as the trees are now at least 2 1/2 metres tall and I imagine we'll probably fruit next season so I would want to treat them wireless app is running before winter. I live in the subtropics North Eastern New South Wales.

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