Thanks for writing. Without being able to see your cassia in person, I can't say for sure what the problem is. (Unfortunately, this free service really isn't designed for diagnosing plant problems because so often you need to see the plants in person to give a reliable answer.) There may even be more than one issue going on.
For more help, I'd contact your Broward County Cooperative Extension Service at: http://www.broward.org/extension/ The staff should be able to help more if you can bring in samples of the leaves for them to examine in person.
---Justin, Senior Garden Editor, BHG.com