Rusty Brown spots on Upper Leaves

[SweetIndica2]

I just put 3 females into flowering, one is a hashberry and the other two are blockhead. Upon my last feeding (2 days ago) the hashberry started showing these rusty brown spots, i did overfeed slightly, as all the plants had like a mm or two of burnt tips on the leaves, but none of the plants showed the rusty spots like the hashberry. Temps are 85-88 during the light on period, and 70-78 at night when the light is off. Humidity is 35-45% usually. The light i am using is an aircooled 1000w hps, the lens is cool to the touch, light is about a foot away from the plants. I fed them 2 tsp of PBP grow, and 3 tsp of PBP Bloom. PH is adjusted to 6.6 before each watering, i haven't been testing run off though. But all the other plants are acting fine and not showing any of these symptoms.

Here are pics of the rusty spots:

 

[inflorescence]

Add cal mag to your regiment.
You've got ca defic.

 

[SweetIndica2]

Yea, i figured it was either a cal def or ph problem. Problem is, there are no stores within a 100 or so miles that would carry cal mag. Is there anything else i can use in a pinch to fix the cal deficiency?

 

[inflorescence]

Are you using ro for your pbp or tap?
PBP is notorious for needing cal mag in RO. Most tap has enough cal mag (hardness).

 

[SweetIndica2]

I use tap, but my water is fairly soft from what i remember. I haven't tested it in awhile though. I actually just found a bottle of growmore micro which says contains calcium and is ph buffered so i'll add a little of that when i water. Thanks for the help.

 

[SweetIndica2]

And, should i give it to them now or wait until next watering. The spots appear to be getting worse by the day.

 

[ninfan77]

You could mix dolomite and water and foliar feed them. I think its 1 TB dolomite per gallon. Not 100% sure on that ratio though.

 

[inflorescence]

You could mix dolomite and water and foliar feed them. I think its 1 TB dolomite per gallon. Not 100% sure on that ratio though.

Yes, mix dolomite and water the plants with this solution but do NOT foliar with dolomite.
Ca alone is a big molecule and it's usually micronized in order for it to work as a foliar and ca combined with carbonate (dolomite) is an even bigger molecule so no way would the ca in dolo be absorbed by the leaves.
Problem is it will also take a while to be absorbed by the roots.

 

[tree&leaf]

I don't agree that plant is Calcium deficient, it looks over-fertilised and burnt to me.

All Mandalas strains are very nutrient efficient and only require very light feeding - there's no reason at all that, that Mandala strain should come out Ca deficient whilst the others don't, being fed the same nutrients - bearing in mind that the Hashberry is pretty nutrient efficient. It's more likely to be overfed than deficient.

The dark green leaves are probably overdosed on Nitrogen.

I'll be interested to see if adding Calcium to that plant cures your problem.

Just my 2 cents..

 

[Guest]

I don't agree that plant is Calcium deficient, it looks over-fertilised and burnt to me.

All Mandalas strains are very nutrient efficient and only require very light feeding - there's no reason at all that, that Mandala strain should come out Ca deficient whilst the others don't, being fed the same nutrients - bearing in mind that the Hashberry is pretty nutrient efficient. It's more likely to be overfed than deficient.

The dark green leaves are probably overdosed on Nitrogen.

I'll be interested to see if adding Calcium to that plant cures your problem.

Just my 2 cents..

I fed them 2 tsp of PBP grow, and 3 tsp of PBP Bloom.

6 of my 10 Mandala Satori just sprouted. Mandala recommends very light nutes for its strains. Sounds like you gave those plants a pretty heavy dose of that Pure Blend to me....at least heavy with regard to the Hashberry.

May I ask, if your plants are in flower, why the PBP Grow at all? The flower has Nitrogen in it. If I recall correctly, Over feeding with Nitrogen can lock out Calcium( the symptom you have). Something about the preference of the plant for N cations over Ca cations I think.

The vast majority of my 30+ years of growing experience is with non cannabis plants so you need the input of the experts on weed here I think. I wouldn't give it anything but water till you hear more. I don't think it is Ca deficiency though.

as above, my 2 cents
Obli

 

[inflorescence]

showing up in younger leaves, ca is immobile.


Ca defic pic from mynamestitch thread

ca defic pic from old AN website

 

[Guest]

I think we agree it appears to be a Ca deficit, the question is why?. I don't think it is a Ca deficit because his other plants aren't showing it. And Hashberry doesn't need the strength of nutes he is giving it. I think Tree&Leaf is correct. That plant suffers from N overload and THAT is locking out the Ca. Adding more Ca may well make things worse.

Obli

 

[Guest]

Look how dark the green is too.

 

[SweetIndica2]

Alright, thanks. Yea, i haven't given it anything yet. I'm going to wait until the next watering (tomorrow or the day after) and i'm going to back off on the N a little, i'm only going to give them .5 tsp or 1 tsp of grow, and 3 tsp bloom. Thanks for the help.