My mandarin trees don't look that good. This is the second year in the ground.
Pic of tango
Pic of satsuma
The satsuma is loosing most of its leaves and the tango has some dead branches and is starting to loose some leaves. I've fertilized a few times this year with a citrus fertilizer. Did I over/under fertilize. I water every three days with drip micro sprayer for 100 minutes. Too little to much water. I have a kishu in same row that looks healthiest. Gold nugget doesn't look bad but hasn't grown since I planted it. All 4 trees have quite a few mandarins.
Possibly too much water, or too little water, hard to know since we don't know where you live, what your weather is like, sun exposure, soil type, etc. Have you checked your soil moisture to determine whether or not you need more or less water? Provide us the above info, and we can help you a little better :-)
I suggest that you perform a skewer / dowel test. Insert and remove and feel of the skewer / dowel is wet or dry. I can't get away with 3 day interval here in Danville... every two days minimum in June-July-August. [trees are in the ground 2 years]
I just went through this drama with my yard. I was doing the good civic duty of minimizing water use - bare minimum due to the drought - and while i was away on an extended trip got a surprise week of 90-100 (this was back in May). Yellow tips, leaf drop, cupping - the whole bit.
I doubled the water and my Okitsu re-leafed within a month. The Owari took a month longer. The roots got toasted so i can't blame them. I always cheer water sprouts now :-)
Having said all that, your pictures show that the roots are not happy.... and symptoms of too much water are very similar to too little water.
Thanks for the replies. I will check moisture with a meter today. It was very hard to walk around the trees since I was growing spaghetti squash as ground cover. The vines dried up and I recently cleaned area up which may be indication of too little water.
I live in Rancho Cucamonga and it's been in the 90s and hotter most of the summer.