Plant Emergency! Mango Plant rusting away

Greetings Gardeners,
I have 2 mangos indoors in a bright big windowed room in San Francisco, CA
They were doing fine until we moved offices and then I noticed the leaves were turning brown, first it was just a leaf at a time, then more and more. The leaves would then just drop off the plant.
Also after we moved we discovered some small bugs on it as well, it looks like small white/clear bugs that turn black as they age. The rusting started around the same time, I have sprayed it with insecticidal soap which was not that effective and changed to Bayer Insect, Disease, & Mite control 3in1. But it has not resolve itself. Most of the leaves have already fallen off one and the other has most of its remaining leaves rusted.

Thanks in advance for your help

circling the drain, so to speak.

I propose that there is no real bug / fungus problem going on, but that there's a major physiological problem (root rot) that may have begun when you changed offices. then light or air changed, the plant's needs changed and it got too wet. It can go all downhill from there, especially as plant owner tries a bit too hard to help it recover.

Now let's see if anyone agrees.

I water it once a week, and its pretty dry here in CA

I hoped to get another opinion on your plants by now.

Can you get a good close up of the bugs? Don't sound like spider mites, but they can be devastating.

If you really want to save these plants, you may need to investigate further. Watering once a week sounds fine, but what kind of soil, how long have the plants been in the pots, does the pot drain freely, etc. I have been very surprised when I have had mysteriously sick plants. When I take them out of the pot, I find roots in bad shape, or roots that are dry inside a thick mass while the soil outside appears wet on top , or water runs around the edges and drains.

I don't think you just need a different spray, fertilizer, or something. If you take the plants out and correct something, will you be happy with plants with leaves just on top?

The plant that has new growth I repotted it last week in hopes it will get better.
They are in ordinary soil... recently I have been adding spent coffee grinds on top as a mulch, maybe it is now retaining too much water? When I was repotting it was kinda moist, one thing i did notice while repotting was the snapping noises coming from the roots. The bugs are pretty much gone... since it is an office maybe someone else was also watering it? Since the pot was clear and I only water it once a week there is no drainage, the container is not permeable.

Also since it was a clear container maybe the sun was directly heating up the soil/roots?
Since no drainage maybe too much water collecting? (Filtered water)
Or maybe it was too dry and the leaves are browning due to no water?

I cant figure it out but sucks to see it in that condition.
Thanks for any help

Here is a pic of the bugs on the mango, they start out as white larva looking things then grow into these black insects.

I can't see the bugs clearly enough to say anything about them. Bugs aren't my forte any way. And I could be wrong about the cause of your plant's illness.

Filtered water is excellent. New growth is a good sign! Maybe it is headed in the right direction since you repotted. It is almost ALWAYS better to keep the plant too dry than too wet.

A pot that does not let excess water run out freely is a set up for sick roots. Best to have a pot that can drain- this can be set inside another pot that does NOT drain but will keep you from having drips on your documents and desk. and the cachepot (non draining cover pot) is NOT an excuse to let the plant sit in a puddle. watering enough but not having the plant drip all over the office is of course a challenge.

There are other plants that tolerate an office very well. Spathiphyllum, Aglaonema, Epipremnum...

The coffee grounds are likely to kill the containerized plant.

FWIW - I think that ultimately you'll find your answer by looking to the condition of the roots, which is where a huge % of problems originate for containerized plants (I'd guess at least 90%), even if indirectly - this includes insect infestations, diseases, poor growth, spoiled foliage/appearance .......... so I'm on the same page as Sally, here.

BTW - while Bayer 3-in-1 is approved for plants grown indoors, you shouldn't be spraying it indoors, so for safety's sake, please be sure to move the plant outdoors in shade to spray & allow it to dry before bringing it in.

Al