Large white spots. Please help.

I have six plants, all different varieties and all different ages, from 3-8 weeks. I'm growing outdoors in Oregon (medical marijuana grower/patient)

I was on vacation and my plants didn't get fed. They JUST started to flower about 4 days ago and I fertilized them yesterday with a fairly strong solution(4 tbsp fish emulsion, 1 tbsp MORbloom to ~ 3 gallons water).

Today all of my plants have large (1/4" - 1/2") whitish spots on the large fan leaves (though even the baby plant has some smaller white spots on its small leaves)

It doesn't appear to be spider mites (phew!) as the spots appear too large from what I've seen on the internets.

Does anyone know the possible causes of this? I've done extensive searching and can't find any photos that look similar to what I'm seeing.

The spots are not on the edges of the leaves and there isn't any browning. The leaves and plant otherwise look perfect.

EDIT: Many of the spots are on the edges of the leaves.

I'll post photos tomorrow if none of you experts can give a possible diagnosis.

Thanks for any help.

Fade On

what is the humidity there. It could be powder mildew. can you wipe it off the plant?

I don't think it's mildew as the spots cannot be wiped off and the humidity is relatively low these days. They're getting lots of sun.

Im having the same prob with 2 of my plants outdoors. I thinks its a ph prob or cal/mag def or both. I showed pics to a couple of guys at the grow shop and they thought it was the same thing without me mentioning what I thought it was. I'd check the ph of your nutes next time before you feed and possibly add some cal/mag. Im adding some tommorrow when I feed, I'll let you know how things turn out in a few days if you'd like.

pictures? I know it is leaf miner season in the northwest.

mm

did you spray the leaves at all? could be water magnification.

i did spray the leaves now that you mention it. I think you may be on to something carokann. I'll keep an eye on them and if the spots don't enlarge I think you hit the nail on the head. Next time I'll be more careful and definitely not get water on their leaves in the heat of the day. Thanks!

Here are some photos of my girls. The spots haven't enlarged and the plants look otherwise very healthy. I'm thinking it was possibly sun damage from water magnification. What do y'all think?


I'm growing 5 plants in 10 gallon smart pots, 1 is a large seedling that will be in a smart pot in a couple weeks.
Strains: Elvy, Goo, Honey Bear, Shiskaberry, Permafrost, and Hollands Hope.

Thanks for all of your help. This is my first grow in many years.