Dwarf Valencia orange - fruit only on lower branches
I am new to citrus growing, so please bear with me. I've searched the posts on this forum but haven't found an answer. Hopefully someone can help. My 3 year old dwarf seedless Valencia orange is planted in the ground in mostly full sun and looks very healthy. There is lots of very dense foliage and new growth (looks more like a bush than a tree), but I'm baffled as to why there is only fruit on the lower part of the tree. The oranges are good size but they are almost completely hidden in the foliage so they never get any sun on them. They taste more sour than sweet. Is this just a normal growth habit for this type of orange, or should I prune to open it up to let light in?