Brown spots followed by necrosis on Mandarin Sunset.

My grape leaf attached by mold https://ibb.co/S74s3Br

Could be one of 3 things,I think. 1. Pest damage (especially that small cluster of spots. 2. Ca, p, or k deficiency or lockout. 3. Wind damage (especially that crispy, yellow, spotty fan leaf) So if its only affecting plants best the wind source it could be burn from to much fan action. This happens to me often and I try to move the plants around the tent a bit to prevent it. If it's affecting overall health check the leaves very closely top and bottom for signs of pests, you'll want a magnifying glass. Hopefully it's just nutrients related and you can adjust your flush and feed fairly easily.

Hey there dirty hippy, that's pH "fluctuations" that have built up over time. the biological additive regime is to blame. turns out that stuff needs to some time to "gear up", ideally you would be preparing your pots and medium well in advance to make sure the biologicals took hold. Especially the kelp extracts. these arent useful so much as they get microbes going really well. Long story short, over time the kelp will gradually raise your pH and it may end up on the high end of the scale just enough to cause what you're seeing . To prevent this from happening or getting worse, go ahead and cut out all the kelp extracts . it wont change a thing but it will prevent it getting worse. Hope this helps ! 🚀

Hey dirty hippy had a look av never seen those brown spots before top leaves or bottom ones a would tidy it up light defoliation and hopefully fresh growth will resume good luck n sorry cany help any more than that peace

I agree. to many nutrients causing burn. You want to use just water for a while. Especially since your using fox farms potting soil. It has organic nutrients in it already. You want to make sure they are used up before adding high concentrations of bottled nuturents. Happy Growing

Nutrient burning from too much nitrogen, as indicated by the very dark green leaves. Possibly with nutrient salt build up in the substrate too, especially if you are not watering to run off each and every time. Or feeding too much, too often, and with too many things. And possibly a combination of all three ideas. Hope this helps, Organoman.