Hello I've recently purchased a few barberries from a local nursery. They are about 4 weeks in the ground now. Per the recommendation of the nursery I've been watering them one good watering every two days. We've also had an abundance of heavy rains for the last couple weeks. It looks like the leaves are dying and falling off at the bottom of the plants. Do you think this is from some type of fungal? Any advise? I can return them for 50% refund if needed.