Help, lemon tree dying
I have a Meyer lemon tree and a stem started to grow from the tip. A few days later, the "bud" turned black/brown and died. I didn't really care, because there was new growth happening else where too. Then, a few days later I saw to tip of the stem turning brown. As the days go on, the brown on the stem goes lower and lower. The stem where it is brown is hard, so I am assuming that it is dead, but why is it spreading down the stem? What do I do? Do I cut off that stem, and if I don't, will it kill the whole tree? And how did this even happen, and how do I prevent it from happening again?
I have many questions, since I am not an experienced citrus grower, and I would love it if someone helped me.