Unable to identify dark grey spots

Hey all! My first time posting but not my first grow. What is going on with these dark grey splotches on my leaves? I’ve had the worst time with these clones of an unknown strain. The older leaves and those closest to the stem base are dying off.

I had been feeding them the Homegrown brand organic nutes and supplementing them with FoxFarm Big Bloom and Kangaroots according to their feeding schedule. I started them using the FoxFarm line and they did fine with that until they didn’t. That’s when I switched over.

They are photoperiods I got back in May and they stalled out 2 months ago when I was on vacay and temps hit 95° for a week which nearly killed them. I trimmed everything that was dying off and they bounced back by filling out but only gained 16” in height in 2 months.

I’ve done 2 autoflowers from seed this season using the exact same feeding schedule and they turned out amazing 🤷🏻

In 10 gallon fabric pots with Ocean Forest soil.

@Stickyfingerz , I’m not a super experienced grower I’m actually on my 3rd grow ever, there is an app called GrowCush you take a picture of the leave or leaves in question and then answer a couple questions and then it’ll give you some answers it’s a great little tool I’m not sure how accurate it is but maybe give it a try it may help

Tips are dark too. I’m a newbie, but, maybe nutrient burn. There’s many more experience people on here that can recognize it. Look at some of the “problem” videos on YouTube. Good luck :sunglasses:

@Stickyfingerz that looks like some insect damage and a fungus. I see what appears to be insect droppings from thrips or caterpillars and those darker circular spots with the gray/brown centers looks like leaf septoria.

That sounds great, but it doesn’t appear to have an iOS version yet. :disappointed:

I would think nutrient burn as well, except it’s only on the oldest growth.

Insects would not settle for just the oldest leaves though, right? I had just treated them both with neem oil last week as well as copper fungicide. The others around them are doing great in the same medium and conditions. I’ve had some powdery white mildew when humidity was around 65% and temps close to 100°. Using a solution of baking soda with a splash of Dawn kept the worst if it at bay. I did lose about 8g of bud from a nearby autoflower that had a touch of bud rot. I attached a full plant pic for a better idea of my situation

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They both nearly died 2 months ago and it’s been rocky ever since.

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@Stickyfingerz if you didn’t treat the soil and still have high humidity you can still get leaf septoria. I looked closer at what I thought was insect droppings and it’s actually just pycnidia forming (the black breeding structures of the fungus) and some of them have the conidia forming (the white spores that spread the fungus).

You can also see clearly that it’s likely leaf septoria because it’s only on the lower and middle portion of the plant mostly on the inside leaves where humidity and lower airflow allow it to breed.

I’d put down a mulch layer and take off the affected leaves and try to increase airflow as much as possible.

Leaf septoria usually doesn’t attack the flowers so it’s mostly just a nuisance unless it gets out of control and takes out all of the foliage. When that happens you’ll have a diminished harvest because you lose all those solar panels for photosynthesis and the stored nutrients. In extreme cases the whole plant can die because it can’t photosynthesize or eat.



How do you recommend going about treating the soil? This is my first time in 10 years of growing that I’ve had to deal with this issue!

What do you suggest for treating the remaining foliage? They are currently outdoors and temps are in the 90’s the rest of the week. I don’t want to bring them indoors and potentially contaminate the phat girls finishing up in my grow room.