I have an idea on what it is but i would like some second opinions before i take action. Its week 4 and its on 2 of the oldest fan leaves only.
Looks like a calcium deficiency in the photo. I’d rub it first just to be certain it isn’t rust mold. Rust mold can cause rust spots that look like a calcium deficiency but they rub off and leave a rust colored stain on your fingers.
@MDBuds What causes rust mold? I use cal mag every watering (3ml per gallon) with RO water. Should i add a lil more?
@2Grow4Love rust mold usually happens with cold night time temperatures and high humidity. Pretty much anything under 60f with humidity over 60 rh. You can treat it with organic fungicides but I prefer to just wipe the plant down and spray with a 50/50 mix of raw or organic milk and water. Milk is actually safer, faster, and more effective than most fungicides.
On the cal mag it depends on what brand and the amount of calcium and magnesium in it on how much you should increase it.
Thanks a million @MDBuds. Your knowledge is second to none!
@2Grow4Love you’re welcome. I appreciate the compliment. Happy growing.
@2Grow4Love also, just to be on the safe side, I’d check the undersides of the leaves just to make sure you don’t have pests. Spidermites can cause the rust spots too. You can use a jeweler’s loupe just like checking for trichs but you’re hunting for mites.
@MDBuds Lol that was the first thing i checked for. I am OCD about pest prevention. Good news is there are none in sight🙏🏼
@2Grow4Love awesome man. Sounds like you got this. Just do the rub test then to diagnose if it’s rust mold if it doesn’t rub off and leave some rust on your fingers proceed as you initially intended by increasing your calmag a little.
@MDBuds 10-4 brother and thanks again!!