I have a chem 91 clone and all the leaves are yellow drying out and dying. The temps are 74F 35H and at night 66F and 45H. Im using Empire Builder soil and i have had nute burn and what i think was a ph lockout this is my first time using this soil and i ran into problems with it. I havent feed this plant in 2 weeks due to nute burn and its just been on a water only diet. every leaf is drying up and curly and falling off. i fed it calmag pure blend pro with distilled water. no pics. its basically all leaves yellow and curling up and they are brittle.
Also, check the breeders info on the strain. Some strains almost all the leaves fall off during flower. I did a group of critical nevel haze that's like this.
Could be nitrogen def as well hard to say without pics I know if I don't feed nitrogen nutes a few weeks into flower mine yellow quick
When you have nute burn you flush the plant and reduce the nutrients...... Is not uncommon for leaves to turn yellow at your stage of flowering... Without a ph tester(a must must) your flying blind....Get a Hanna combo. There not cheap but, will be the last one you will ever buy... Limited to diagnosis without pics and more info on the grow and feeding schedule...
I have a cheap digital PH meter and it sucks. Pick up a fish tank PH test kit at a pet store. They're cheap and perfect for the PH we're looking for with our "hobby". I bought one today and it works great for $6. I think it measures 6.0-7.6 Good Luck