Trees in question: Ponderosa Lemon and Trovita Orange.

Zone: 4 (Minnesota)

window: South Facing

fertilizer: foliage pro

Hello all,

I have been noticing some tiny dark brown/ black spots on the stems and leaves of my Ponderosa lemon tree. Some (on the stems) can be scraped off, while others (on the leaves) seem to be more ingrained in the leaf. A few leaves have been coming off as well. These leaves have been rolled up on themselves. It’s hard to say if they come off the tree that way or if they start to roll up after sitting off the tree and drying out. Any ideas about what I might be dealing with here? Any thoughts on treatment? (picture attached below)

Party bonus if you feel like confirming/denying my thoughts on why my orange tree has been having yellowing leaves/leaf drop. Both trees are in a reptibark/crushed granite/turface mix. The mix was screened using window screen, but I do wonder if the reptibark is a little too coarse for the mix. I only water when my moisture meter reads dry/when the mix feels dry when testing with my finger. This works out to be about once a week to week and a half. Despite all this, the tree is acting like it has been over watered. I have noticed some teeny bugs in the soil after watering... possibly fungus gnats? I haven’t seen any adults flying around though. I did a diluted peroxide drench for my last watering and plan to hold off on watering for awhile now. I just worry about the tree getting too dry... It often looks thirsty after about a week and a half. Anything else I should be trying?

Other information that may be relevant- I have recently installed two (one for each tree) 40 watt LED grow lights (positioned approximately 20 inches above each tree). I only mention this because my husband seems to think the lights are somehow causing the trees to be stressed out. I hate to admit it, but he might be right. The trees were putting on a bunch of flowers/new (leggy) growth before the lights... Now... not so much.So I dialed back the amount of time the lights are on from 12 hrs to 8. Maybe it was too much too soon?

Th