I have had this jade plant for 3-4 years and it was doing fine until just recently when I noticed a lot of leaves dropping off. First healthy ones were dropping, then they started drying up and before they dropped. It also has a lot of brown scaly bark covering the bottom of the trunks. I have attached pictures. Should I prune the plant now (late summer)? Where should I be cutting back if I do? It's too tall and weak to hold itself up, so I have it staked. I would love to have a full jade plant. Please help!