Wow I never knew they were that harmful.
I like the Avid, but it is good to rotate, I usually use Forbid in the spring, Avid in the mid summer, and Bayer Insect, disease, and mite control in the fall. But this year I didn't do it and paid the price.I hate-um too. This year I popped for some Abamectin (generic Avid) and a tyvek suit--It works.
I've never seen spider mite damage look like that. Mites are sucking insects; they suck the juices from the leaves, but don't "eat" them. Neither do they to my knowledge defoliate a plant.
You said these were Serissa. It seems more likely to me that something else may have been involved -- like too many chemicals applied at once -- or the Serissa merely acting like Serissa?
Regarding Serissas, is it normal for them to have greenish fungus-looking growth around the base of the trunk? I have one that i have been trying to rid of what is suspiciously close to that green ring around the first picture and thought it was due to my watering habits at first. I almost desertified the tree trying to kill the greenish crap by laying off the watering. As soon as i water the green comes creeping up the trunk.....