Loganberry Brown Edged Leaves

Woz starts with ...
I have recently planted two Loganberry Plants into pots using a quality potting mix. Initially they started to grow with prolific green healthy leaves. From the photograph it can be seen that the edge of the leaves is now browning and deteriorating further. We are coastal NSW and are watered on a automatic system daily sufficiently to wet the ground but not waterlog (approx. 4 minutes). Can anyone suggest where I have gone wrong and how I possibly can reverse the problem. Many thanks.

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