Weird spots on leaves! Can not figure out.

Most of response I’ve gotten from other forums was a potassium deficiency. Not sure what’s going on but they are only on 4-5 fan leaves that are closest to the fan. Growing in coco.

I am in week 4 of flowering. Temps are 75 day, 65 night. Humidity 30-50. Have dehu Light is 315cmh in a 4x4 tent. Has heat blowing in bottom when needed and exhaust fan pulling air from top. Have oscillating fans. Using h3ads formula, with slight modification to adjust to plants needs. 4ml micro, 10ml bloom per gal, ro water. Ph 5.8. Ec 1.6
Just started getting these spots and it’s only on like 4 or 5 fan leaves that are closest to the oscillating fan side. doesn’t seem to be spreading to other leaves yet but still worried

I was watering twice a day to 10-20% runoff but after seeing these spots develop I decided to back off to once per day.

Not sure if it’s fungus or nutrient deficiency? Any help would be really apprecited! Thanks

It does look like you're having potassium def.

TheSadVeryBadMadGrower said:

It does look like you're having potassium def.

How to fix Cannabis Potassium Deficiency (K) Pics & Symptoms

Leaves with a potassium deficiency have yellow, brown, or burnt edges and tips. It may look like nutrient burn, but the leaf margins also turn yellow.

www.growweedeasy.com

Click to expand...

Thanks for the response and the link. The article stated over watering can be causing the issue. Hopefully watering once per day fixes the issue. Not nothing serious but I like to get on top of the problem at the first signs

I typically don’t water everyday myself, maybe u have really thirsty girls or girl. I feed and water every other day.

Feed
Nothing
Water
Nothing
Feed
Nothing
And so on..


Maybe over watering/feeding is your issue if you are doing either everyday. You may also have a potassium problem like the 1st responder said. Kind of hard to say. Looks like a trial and error situation to weed out the issue, no pun intended. I had fan leaves issues also, mine just had reddish/brown spots. I had to back off the Nutes for a while ( not stopping entirely) to stop it from getting worse and affecting the entire plant.

Dontjudgeme said:

I typically don’t water everyday myself, maybe u have really thirsty girls or girl. I feed and water every other day.

Feed
Nothing
Water
Nothing
Feed
Nothing
And so on..


Maybe over watering/feeding is your issue if you are doing either everyday. You may also have a potassium problem like the 1st responder said. Kind of hard to say. Looks like a trial and error situation to weed out the issue, no pun intended. I had fan leaves issues also, mine just had reddish/brown spots. I had to back off the Nutes for a while ( not stopping entirely) to stop it from getting worse and affecting the entire plant.

Click to expand...

Tanks for the advice. I’m in coco and have always read to feed with every watering and not to let the medium dry out

My mistake, u did mention that u were in coco. In that case, watering daily is a must. Not sure about the need to water with Nutes everyday though. How large are your pots?

Have you looked for mites with a magnifying glass? Have you been spraying them, is that residue from a foliar spray? How hot is it? Sometimes they'll sawtooth up like that with heat stress. Use an IR gun to measure your leaf temp. Could be windburn too from the fan, maybe most likely. I don't think its lack of K. 1.6 is plenty, could have a build up, I'd flush them if its been few weeks since your last flush.

Feed every day...and don't flush them. If you don't feed every day and you do try to flush them, you're just asking for issues. Full plant pics would be more useful vs. a few leaves. Never the less, I wouldn't sweat it. Just watch them daily and be sure your pH and nutrients are line. Good luck.

Yes looked for bugs with magnifying glass. There is 0 sign of pests. I checked my ec and Ppm again and they were way too high from what I seen unless my tdm meter went crazy out of no where. Like I said it’s just a few leaves, but I get ocd about this stuff. Here is whole plant pic and a pic of the section with bad leaves. A few days went by and it looks more like nutrient burn more than anything, which would make sense if my ec is way too high.

I get the whole OCD thing. One minor thing gets over looked and the entire plant goes haywire. Overall it looks pretty healthy. Typically it’s not that difficult to recover from a nute burn if that’s what u suspect it being.

Have you tried moving fan up a little more in height?
I only say that because the effected area looks right at the fan...if I'm see the pics correctly.
Usually if its something like nutes you see it in more then 1 area.
Where when its showing problem in 1 area its usually something in that area like fan or intake etc.
Best of luck and happy growing