Over Water?

Also like smokeanagan said, it could be a ph lockout but your leaves still look attached. If the leaves and new growth are dying off raise your ph a couple parts per. The rusted spots are telling me your low on potassium and the iron and copper boron micros are rusting up. Usually tap water is bad for it because of the chlorine. Tea up some Epsom and cal mag and use that when you feed.

The little spots are from one of few things. Rather your plants are using iron from a deficiency such as potassium or magnesium in places it doesn’t need to stay alive. Usually from spraying leaves in lights on or other def. , or Your plants leaves are looking yellow because they are lacking nitrogen needed before flower. If you didn’t give enough nitrogen while in veg, it’s a 50-50 and I would use a 8-8-4 ratio during flower. Even though they don’t require much nitrogen during flower they still require a little. If they didn’t have enough nitrogen during veg, whatever nitrogen they do have left will get sucked in and that plant will die. To me it looks like a calcium issue because your preflowers have nice pistil formation. If the leaves only had crinkles on tips I’d say nitrogen or potassium , but where there are black spots on your leaves, Its telling me that the plants are using its iron to stay alive. I would use some cal mag every other watering and since your in preflower I would switch to a 2-8-4 bloom or I would go some black magic 5-5-5 all purpose and make a foliage tea to spray the leaves since it has the needs and calcium the plants might of missed out on. Look to see if the black spots have a purple tone to them. If so it’s iron. It’s not necessarily an iron deficiency it’s just use an extra iron and put it in places other than the roots. Good luck and I hope it helps

I think you need watch the ph of your water and adjust accordingly. Might be a nutrient lock out from this

Hey Marc7201vos plantes reflète un blocage de nutrition du a un ph mal adapté. Veuillez vérifier le ph du sol utilisé et ajusté l'eau d'irrigation irriguer jusqu'a ruissellement répéter ce geste 2 à 3fois. #LoveUnityAndPeace

If your using soil pH to 6.5-6.8. If you are using Hydro like coco( please make sure you adjust pH to 6.0 even when watering or feeding. I always check ph first when I run into things. Also make sure your pH meter is calibrated. You are feeding 600 and for some reason your ant can't absorb it.. that means your pH is off to a point where any is not absorbing. If pH is fine and pH meter is fine. Raise ppm from 600 to 800-850 ppms.. Definitely will fix your problem.

Hi, by the looks, you have deficiency all around: NPK and micro nutrients cal-mag. Furthermore, your PH could be off. Right now, your plants need more phosphorus in flower, but be sure to incorporate all!