A good question! The rosehip tree (or rose tree, I suppose) was planted by a previous owner of the house. It has small pink flowers in spring and massive red hips in autumn, so it's quite unlike a cultivated rose. I have no idea what variety it is, but it makes plentiful rosehip syrup. It has no pests at all, indeed no kind of maintenance has been required except to cut it back when it got too large.