I have a Dendrobium that has dropped leafs a little yellowing and black. the leafs are firm, the bulb is purplish, no odor roots firm, was split 2 weeksgo and transplanted with sterile technique please help. Its a huge pla the rest of plant is very healthy. is this a normalcy or a pest or disease problem. help i'm desperate... for your advice. their is a pic in my gallery I am not familiar with comp tech so please bear with me.........thanks