Sorry its taken so long to post a photo. hope it works! I have one of the vines (there are multiple ones around the base of the tree) up into the tree & showing a patch of brown leaves & another photo of the base of the tree where they are planted.
Sorrry i cant post a photo of the leaves with the browning at the centre going out from the veins - i didnt think at the time of photos but will do next time i find some.
hope this helps to give me some guidance. thanks