I realize the pictures may not give you enough to go on to make a quick judgement.
White Widow, 1 full week of veg, Fox Farm Ocean Forest Soil, PH was pushing 7 after last watering. Since that watering I have determined that my water is PH 7.8 ish. (depends on how long ago it rained.)
I just noticed this morning, don’t remember seeing anything last night. This is the only plant with any problems that I can see.
My guess is it has to do with the PH, or the little gnats that have been showing up.
Too many gnats usually means too much water, the soil might not be draining as well in this container and this along with pH could certainly cause deficiencies or damage that will show in the leaves.
Get some PH down. If you do not want to wait on shipping; Go to auto parts store and buy a battery refill. This contains pure diluted sulfuric acid, and is perfect for use with plants. I buy the big shop box and use it in my greenhouse for all veggies. much better calue that the diluted phosphoric acid sold as “PH down”
First indoor grow. Strawberry Kush. Germinateded 11/1. began flowering 1/15, 12/12. 2 plants in a grow box. 68-74 F. Humidity 40-60% pH 6-7. 2 T5 Flourescents. 120 cfm fan on and off with heater. Miracle grow 1/2 strength every other water cycle. Thought it might be thrips, Two treatment with NEEM oil. Thought it might be calcium. One dose lime. Leaves are damping off at the stem and wilting. EVERYTHING is new. Box, soil, smart pots. Any help would be appreciated.
What are you feeding it? Even if your pH is ok, if you are not feeding it regularly, you could still end up with a deficiency.