16/07 - Beginning of week 2 in veg. I applied a garlic solution to prevent pests. I am trying to fine-tune water yet.
18/07 - Some problems with nutrients. I flushed a little bit and monitored the plants. Give filtered dechlorinated water only. The new leaves seem healthy.
20/07 - Finally fine-tuned water and nutrients. The plant looks beautiful. I applied a little bit of LST and the response was almost instantaneous!
22/07 - Last day in week 2 of veg. Trying to correct my soil pH.
Only on one leaf of one plant. Is this some fungus or virus?
It looks a bit like coffee rust, but I couldn't find anything else like it.
How should I proceed?
Thanks in advance!
Pretty certain this is Leaf Spot Fungus otherwise known as Rust Fungus... and you'll need to jump on this quickly as it spreads fast... it spreads by spores that you can't even see so don't think you've got any time to waste here... I won't go into all the details of what you need to do as this article is very thorough.. Do give it a read and get going so you don't lose your entire grow...
https://www.urbanorganicyield.com/rust-spots-on-leaves-during-flowering/
Good luck!