Have you checked for root aphids?
They are impossible to see without a loop.
Also, I had dying plants on my hands, and treated with aspirin. 325 milligrams per gallon of water, and plants made a miraculous recovery in 48 hours.
The aspirin boosts the plants immune system. Can be used as foliar spray also.
Grasping at straws here, but good luck.
appreciate it! never had root aphids and am pretty sure i dont, but will look. have merit 70 for any root bug problems.
aspirin huh? may try anything at this point......