Hi, I am new to this forum, and relatively new to Bonsai. I work in a gift shop that sells Bonsai, and when a former supervisor was getting ready to retire, he started training me to take over the Bonsai. I do the best I can, but with many other responsibilities, both at work and home, I haven't been able to put as much time as I would like into thoroughly researching every species of tree we carry; I research when I can, but haven't gotten deep enough to know what is going on here, or what to do about it.

We have a rather large Serissa, about 10 years old and about 14-ish inches from the top of the pot. Some of the leaves started to turn gray about a week ago. Now more of the leaves have turned gray, and a few are turning brown and falling off. What could be causing this? The tree has not had any flowers since we got it in late last summer.

Any help or advice you can give as far as what it is, to do or what direction to look in, would be much appreciated.
Thanks,
K