Hello GC. This is a public service announcement from dankohzee. I've recently discovered the calcium deficiency I have been treating unsuccessfully is actually a leaf fungus. The two are very easily confused for several reaasons I don't have time to list right now. I just want to get this out there because this leaf fungus is quick and may not kill your plant immediately, but it will destroy any possibility of a decent yield within days. Here are some shots of what this can look like. Keep in mind, though, that there are numerous molds and their appearance can vary slightly. One thing, however, is consistant: brown spots followed by leaf yellowing and leaf drop in cannabis. I wish I had more time to develop this thread further right now, but I'm literally in the process of trying to save my crop. Citrus, fruit, and nut spray, AKA sulphur spray is supposed to be the cure for this. We'll see.
Great pics of a fungus problem! Thanks for taking the time to inform us! Good luck!! Let us know what happens!
Neem oil has decent anti-fungal properties that could prevent this from happening if you have had issues with it. Perhaps you could give that a shot. A sulphur spray would work great but if you could get your hands on a sulphur vaporizer, it will clear it up for sure and also help with pests if any are present. Smells like ass though
Spray with a Baking Soda Water solution, 1 tablespoon of baking soda to 1 gallon of water, seems to be working good for me.