White spots on leaves - Powdery Mildew and Spider Mites unlikely!

[FlyingHedgehog]

Hello fellow growers,
Nearly four months into growing, I have noticed some white spots on the leaves of my plants.
Of course I checked online, but the spots seem too defined (not powdery enough) for powdery mildew, but I also checked very well and couldn't find any webs or mites, which most people said would definitely be found in the case of spider mites.
If you think it's one of the two anyway or have any idea what else it could be, I would be really grateful!!
Thanks in advance,
FlyingHedgehog

More infos:
Strain: White Widow
Nutrients: T.A. Tripart
Lights: 600Watt LEDs
Growmedium: Soil



====== UPDATE ======

Following the advice of multiple replies, I checked again and more thoroughly for spider mites, and you guys were indeed right! The parasites have infiltrated my growroom. Thankfully I seem to have discovered it in the early stages as there are not too many yet and zero webs, and I started a treatment. Hopefully it will be alright! Thanks a lot for the help and happy growing to everyone xxx

[PLreef]

You won't always find webs when you have spider mites. The tiny white dots are definitely a red flag. Check a leaf the has the white dots and carefully look on the underside of it. Mites are freaking tiny but you can see them with the naked eye. Do you have a jeweler's loupe or a magnifying glass?
I had them recently and they are assholes. If you do have them you'll want to take steps asap to rid your grow of them. I using predatory mites to kill off any lingering mites I might have left from my last battle..
Let us know what you find. Good luck

[kingfish]

I have to agree with PLreef. Looks like "The Borg" to me.

[FlyingHedgehog]

Ok, thanks so much for the reply. I do have a jeweler's loupe and checked the underside of the affected leaves, but I really couldn't find anything! But I will double check again and keep you updated.

[SoOrbudgal]

I was gonna say exactly that, but grower sounded convinced they are not so............

[FlyingHedgehog]

I did the checks I found online, but I could be mistaken of course. I'll double check again, thanks for the reply!

[dilvish]

you're at 16 weeks? I didn't see any buds. anyway if it's something new at 16 weeks I wouldn't really worry about it unless it gets worse. Maybe an accidental overspray from the nutes? It can sometimes leave those kind of marks. Just check to make sure everything else is correct and check the roots to make sure the plant isn't root bound.

[FlyingHedgehog]

Yes, it's the first time I have non-auto strains and I want to let them get really big before switching to flowering. Thanks for the reply, I'll consider those tips as well! Though the other growers seem to suspect spider mites after all, in which case it is important to act... I'll recheck and update the post if I find the problem.

[dilvish]

if it is spider mites just use Diatomaceous Earth. sprinkle a thin layer on the top of the soil/coir and spray the plant with a mixture of 1 teaspoon with one litre of water. let it sit on the plant for a day then rinse/spray it off with clean water.

[FlyingHedgehog]

Thanks for the tipp! Following google's advice I bought some other stuff, but if I see no change I'll try your method.