Blueberry bush lost all its leaves
For her birthday in the spring I bought my aged ma a blueberry bush. It's about 2 - 3' tall, with about 5 main stems, in a pot (too small for it) of ericaceous compost. It's produced a little fruit. Last week it lost all its leaves and is looking a bit sorry for itself. Is this likely to be early autumnal leaf fall or is something wrong? She's been watering it assiduously all summer - possibly too much at times?
Any ideas? Apart from potting it on, how do I prune it?