Rust spots getting worse? could it be fungus or deficiency?

Hi again all.
My poor poor mango kush is in trouble again. I have done a google search and being a newbie not sure if she has rust fungus, deficiency/toxicity, light burn or a pest??
I know she had nitrogen issues awhile ago so I cut right back on fertiliser.

She had gnats hanging around a few months ago until I dried out the soil and added a bowl of vinegar dish soap and they have gone.

She is in week 4 -5 of flower and the rust spots started to show about a week ago and they seem to be spreading mainly on the sides of the leaves mainly and some have a slight curl downwards.

Not sure if this is a fungus or crystal. I prefer it be the latter.

A few more through a loupe .
This one is the reason I wonder if it’s a fungus. I read that fungus is raised and not within the leaves.

This is the bottom of the leaf. I hope you can see how it is curling underneath.

Only the brown and green are the leaf the rippled grey is the table it was on.

Strain: Mango Kush
Age: 16 weeks. in flower 4 - 5 weeks.
problems: eaten by strawberry slugs, nitrogen toxicity, split stem, now this :-(.
Medium: 50/50 Coco Perlite. (still has some old soil around the base from when I transplanted.
Feed: ozi magic grow juice monsta bud. recommended dosage once a week.
pH: 5.5 (was 6.5 until last week)
Tent: 1mx1mx2m
Light 450W

Question: If it is rust fungus is it fixable this late in flower or dangerous to health if smoked? and will any treatment effect taste?

Looks like a calcium deficiency . Are you any using cal/mag additives?


I have been using ozi magic grow juice monsta bud as per label;

I’m not familiar with that product. I do know that coco coir is a calcium and mag hog. I have the same issue currently also on week 5 using Adavanced nutrients for coco. This late in flower your going to see deficiencies. I feed full dose of nutrients every other day and add a 1/2 tbs of Epsom salt to help with Mag



I agree, I think @Watt-Sun nailed it. It looks like calcium deficiency to me, too. But before you adjust your feeding, make sure you pH is near 5.8 so she can get the goods. Depending on the nutrient line, I believe cal/mag gets cut back later in flower, yeah?


Not sure about when to cut back. AN nutrient line doesn’t reccomend using cal/mag because it’s coco specific it’s suppose to be higher in calcium and mag. Since I stopped giving plain water every 3rd feeding I haven’t had anymore spots appear :crossed_fingers:


@Watt-Sun @elheffe702

I use epsom salts to bring the pH down, then I add their nutes. I would think they are getting plenty of that. I use 2tbsp per 600ml water now with a pH as per a gardening site I was reading. Was told I can;t go wrong with E.S as plants love it.

The newer leaves have been curling but not up or down but in a moon shape/

Epsom salt doesn’t supply calcium.


@BobbyDigital is right . Epsom salt will give them the Mag they need but not calcium.

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I was/am using it solely as a pH adjuster as my water is 7.1 via a bench-top water filter. I could find no other way tp bring it down.

Several good PH down products are available at grow stores…or online.

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I am doing a search as we speak :slight_smile:

Walmart $4.50
Citric acid granules.
Would only take 1/8 tsp or so to drop a gallon to 6.5 or lower from your 7.1


Calmag isn’t a nutrient as such it has calcium and magnesium 2 separate secondary nutrients.
If you want to just feed them some calcium and you eat eggs take the crushed shells and cover them in vinegar and they will bubble and tomorrow strain out the liquid and mix in water and feed. You can top dress the left over shells.
Taste the liquid shouldn’t taste vinegary

Epsom salt provides magnesium and sulfur

So you don’t have to always feed with calcium and magnesium (CalMag) if they aren’t needing both all the time.

Hope this helps.



That’s a good one! Should put it on the charts and graphs thread. :v:

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