Yellow spots, slight leaf deformaties: Can anyone help identify please?

Outdoor, container grow in Northern California. Strain is Strawnana, two weeks into flowering.

A few days ago noticed a couple leaves with yellow spots, one was deformed (half of the leaf was narrower and curled), then today I’m noticing a lot more (I’ve cut them off - about 2 dozen). The spots are almost all fan leaves and can show up anywhere on the plant (bottom and middle mostly). Plants otherwise looking very healthy. I have other strains nearby and they don’t have this problem.

Something to mention: Saturday night we had a very atypical (for NorCal) thunderstorm, with lightning, thunder, wind and light rain. The plants got a little rain before I could cover them, and they dried out pretty quickly the next am when the sun came out.

I could really use some help identifying problem and solution - thanks!

1 Like

Looks like a nutrient problem to me

Great resource. Thank you.

Have you eliminated a possible pest issue? Could be lacking in magnesium? It wouldnt hurt to apply a tablespoon per gallon of epsom salts. Make sure to use horticultural stuff. It likely wont fix the damaged leaves but will slow down the progression and hopefully stop it all together.

1 Like

No problem! and i agree with @Cannabian i don’t think a little epsom would hurt if you haven’t tried it.

Thanks for the replies - very helpful. I’ll try the magnesium supplement and see how it goes.

Thanks again, really appreciate it.

Is very interesting. I have:
One Blue Dream,
One Blue Cookie,
One Black Jack,
One Vanilla Frosting and
One Strawana.
All are planted in 7 gal fiber pots, same soil mix, watered and Fox Farm Trio fertilized on the same schedule. According to ph strips everything is hanging in that neutral zone.
My Blue Dream has had this same issue, yellow spots, for some time now. All the other plants are fine. Maybe the Blue Dream needs more magnesium. It definitely is the fastest grower. Have to go check the magnesium content in the Fox Farm. Just seems like with all things being equal, all plants would have yellow spots. Then again, with the thunderstorms came a heat wave that caught me off guard. Blue Dream and Blue Cookies took it hard with a lot of leaves going yellow and burnt tips. Went from watering every 48 hours to every 24 hours but one afternoon of 98 degrees did it’s damage. The other three plants were fine.

Hey GTDR, definitely looks like the same problem. After the replies to my post I did a little reading this a.m. then stopped by Global Garden Supply in Burlingame (it sounds like you’re in NorCal as well). I showed someone I think is the owner (a great guy - very knowledgeable) a photo of the spots and he immediately agreed - magnesium deficiency! He recommended a product called CALiMAGic that you add to your nutes when feeding. I just fed them so we’ll see, but he seemed confident the CALiMAGic would do the trick.
BTW, I have four plants: the two Strawnana’s with the spots and a Vanilla Frosting and Purple Punch with no spots. The Strawnana’s were definitely the faster growers. The GGS guy suggested adding the supplement when feeding all four plants, saying it would definitely help the Strawnana’s and might help the other two avoid a magnesium deficiency but in any event wouldn’t hurt them.


Be sure to loo really closely under your leaves.

In the meantime, adding a LITTLE extra magnesium won’t hurt

Now What? I’ve been fighting these little green wormie things, on Blue Cookies for a few weeks. They munch a lot! They are really hard to find, I have spent hours looking for them, got three of them, but they blend in so nicely with the plant it’s just luck when I find one. I’m about to go nuclear on them. Today I spotted these little buggers insisting on landing and sitting on my girls. Friend or foe I ask?
And along with the heat wave there is a fire on the coast and the air is heavy with smoke and the smell of smoldering wood.
Which brings up more questions. Like how did all the wildfires in California affect cannabis crops the last couple of years? Probably a question for somewhere else in the forum.
I’m staring deeply into the crystal ball and I see a trip to the nursery looming in my future :slight_smile: magnesium grasshopper, magnesium

Bonide captain jacks dead bug brew. Knocked my Caterpillar and thrips down to non existent after 1 app…