Brown spots on Girl Scout Cookies leaves

So I’ve been getting these brown spots showing up on leaves of the Girl Scout Cookies I grew from healthy clones. Seems to get less prominent when I placed a couple of the plants in my flower tent. I sprayed Safer Soap in case it was insects, and also used an anti-fungal in case it was some kind of mold/fungus. I’ve been removing the affected leaves as well.

Anyone have any ideas? Thanks.


Do the brown spots have a yellow circle around them?


Ohhh, yeah they do @nacho…that’s a classic case…

I’ll let you help @bluedreamhazer out here as you’re well versed in Alternaria infections…



Welcome to the forum! I think you have Alternaria, here is how to treat your plants and grow area.

Remove all the bad leaves and mist your plants with Hypochlorous Acid (HOCI) or Hydrogen Peroxide 3% (h2o2). Use the HOCI at full strength all over the plant, to include under the remaining leaves and spray down your grow area. It will spread like wild fire if you don’t! I spray just before lights out and haven’t had a problem with it. I have had Alternaria in a tent before, nasty crap if not treated asap. I have been told by other growers they fog their plants and tents several times, but with HOCI one heavy treatment will do the job. If you use Hydrogen Peroxide 3% (h2o2) 3% it takes 3 treatments over 3 days and will probably come back a few weeks later. Make sure you have good airflow and good exhaust, and keep your eye on temperature and humidity levels.