Cal Mag Problems or something else?

Background info:

Medium: Soil
Strain: Cheese
How far gone: 4 weeks into flower
Tent size: 150 x 150cm
Light: 750w
Canapy distance to light: 20"
Extraction fan: 10"
Internal fan: 12" ocolating fan aimed at light and across canopy
Day temps: 25
Night temps: 17
Pot Size: 25 ltr
Nutrients: Hesi full range
PH: 6.2 - 6.8
EC: 1.3 - 1.7

I first noticed the problem about 3 weeks ago and assumed cal/mag deficiencies due to the purple stems and the brown spots starting to appear so started to add a cal/mag supplement to my feed schedule -
Nothing changed over the next 7-10 days, so flushed as thought it maybe a nute lock.

I have 25 litre pots so used 50 liters of water ph'd to 6.5, I should have really used 75 liters of water but time constraints and moving the water meant I could only use 50 liters and not 3 x your pot size as per all the flushing guide lines. On the final few liters of water i put though I included the cal mag and 1/4 strength nutes, I've since increased back up to full strength but gradually not to shock them.

I took a leaf sample to my local grow store and they agreed that it was a cal mag def. As above I had already purchased a cal/mag supplement from them the week before so they suggested I try a folilar spray, I used the spray but no improvement, if anything they got worse

I'm pulling off each leaf in which 50% of it is brown and where the ends are curling upwards which are beyond repair and each morning another leaf has the same symptoms, it mostly effects the large fan leaves but is now moving to the smaller leaves underneath the bud sites.

Finally, I notice some spider mites about 10 days ago so used a spray 20 mins before lights out and turned the wattage down to 400w and lifted the light to 25" above the canopy so the leaves would not burn - I'm not sure if this made the leaf ends curl up on themselves, as I said it was only 20 mins before lights out and the light was turned down to 400w and the lights were raised to 25" above the canopy.

*Whenever I have had cal/mag problems before the leaves have gone very yellow with brown spots where as now they are still greenish and look healthy apart from the rust spots and the leaves.

Any suggestions please ))

How often do you water? What is your water source? Do you let them dry out between watering?

not knowing any thing about your grow style,i would guess phosphate or lack of,i say that because I c lots of purple?

Moldy said:

How often do you water? What is your water source? Do you let them dry out between watering?

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Hi Moldy,

Before I had the problems, every 2-3 days all dependent on how light the pots were.

Water source is tap, I leave 24 hours then skim any chemicals off the top.

Currently they are very wet due to panic attempts to nurse then back to health so leaving then for a few days to dry out with a dehumidifier on.

I forgot to mention when I flushed them, the nutes I used on the last few liters of water were Revive from advanced nutes as these have all the trace elements in where as flower if only nutes don't have them in such abundance. Since then I've switched back to my normal nutes but only 1/2 to 3/4 strength.

Thanks

Looks like a bit of P deficiency but also Calcium too, is your light LED?

thumper60 said:

not knowing any thing about your grow style,i would guess phosphate or lack of,i say that because I c lots of purple?

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budman111 said:

Looks like a bit of P deficiency but also Calcium too, is your light LED?

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Thanks both,

Thumper - Could be a good call actually, the bible I use doesn't show the problems I have for P, but just done a quick search and u could be right

Bud man - I'm using a gavita hps, 660w upto 1150w.

Thanks again guys

I'm going to do some phosphorus investigations now.

It looks like deficiencies but I'd guess the cause is lockout. I'm guessing you burned your plants and did the flush with revive to fix?

Did you pH your water?
What's your soil pH?
How long between true nutrient feedings?

Most nutrient lines will have everything you need so real deficiencies like that, especially with tap water, aren't too likely. It's usually a lockout.

Thank Trimothy (Great name

I flushed because after 7-10 days of using the cal/mag supplement nothing changed and the leaves were getting worse so I suspected a lock out, I used revive for the last few liters as its made up of mostly base minerals and not the addition things they put in a nute for flowering only so thought this was best... I've since switched back to my normal nutes but nothing is improving.

I always PH and the run off measured 6.3 - 6.5 which I was happy with.

I tend to feed, feed, water then repeat.

Maybe by using the additional cal/mag I've locked out the phosphorus?

Wait, are you expecting the damage to improve? It wont, ever.

Or are you seeing new damage and damage on new growth?

If you aren't seeing new damage or other new problems, your problem is likely resolved, you'll just have to get by with an ugly, less productive plant.

What you are seeing is the aftermath of mite damage. I picked mine early rather than deal with bugs in my buds. (washed before drying)
Some of my veg plants recovered nicely but others are still struggling. The indica did way better overall. My blue dream and Durban poison were decimated.

TrimothyLeary said:

Wait, are you expecting the damage to improve? It wont, ever.

Or are you seeing new damage and damage on new growth?

If you aren't seeing new damage or other new problems, your problem is likely resolved, you'll just have to get by with an ugly, less productive plant.

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Trimothy thanks again, I'm expecting the leaves which have the issues to stay as was and for it not to spread to other leaves which it's currently doing.

I'm actually pulling off the leaves when they are 50% brown and all curled up as I believe these are toxic to the plant but the next day other leaves are showing the same symptoms and within a few days the once green leaves are now browning and curling up like the pics which is why I don't think I've resolved the problem

Chunky Stool said:

What you are seeing is the aftermath of mite damage. I picked mine early rather than deal with bugs in my buds. (washed before drying)
Some of my veg plants recovered nicely but others are still struggling. The indica did way better overall. My blue dream and Durban poison were decimated.
View attachment 3626455

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Thanks Chunky, I check daily for spider mites and thrips as I've had them before but cannot see anything at present which is why is thought is was a nute issue?

Continues to spread...

Doesn't look like mites to me but I've only had them once, so I can't be 100%.

I think calcium toxicity can lockup magnesium, or maybe it's the other way around.

If it were my plant I'd flush the bejeesus out of it, feed a 1/4 dose normal nutes, and hope for the best.

Thanks Trim, I'll do it to one and see how it goes

Flushing done with 3 x The volume of water that the pots are and then a 1/4 strength nutes to end. It's been 12 hours and 50% of the leaves which yesterday were uneffected are now effected I picked off the badly damaged leaves whilst flushing so the plants looked normal but now it looks like I've left them on...

How long do you think before I see any improvement from flushing, or in this case before the leaves stop curling and browning?

Also when would be best to feed next? I've pretty much flushed all existing nutes and replaced with 1/4 Strength so when should this go back up to my std feeding schedule?

Maybe next feeding, or the one after. But let your soil dry out first. Just gonna have to watch and hope and be patient. That's a lot of leaves to lose.

Now you're between a rock & a hard place. Your plants aren't going to drink much water for a while -- and you just watered the shit out of em.
You can hope for the best or repot into soil that is extremely porous. Repotting adds more stress so I could go either way.
Good luck.

Thanks both

I've got a dehumidifier running so that should hopefully dry the soil quicker... I would repot but they are in 25 ltr pots which are huge so think I'll sit it out and hope

I would guess that your calcium is locked out or suffering low osmosis.
Try some bvits and enzimes to recharge your soil also some mollasis to replenish the sugar/carbohydrates for microbial activity, as you are in late flower and this is the time the plant stops emitting sugars at the roots as its pushing them into the bud to ensure the best start after pollination when the buds fall. These sugars kick start the microbes in the soil when they recieve the sugars in the bud.
That's how I understand it anyway.

Edit: forgot to add, remember less is more, gradual additions keep the girls happy

Thanks The Nine,

I added enzymes with the 1/4 strength nutes and will add some vits when I water next.

They are looking bad The leaves are browning and curling at an alarming rate despite the flush.

At this point I'm thinking it's going to be a total write off, hopefully I'll be able to water with some more nutes on Monday but at this point I can't seem them lasting another week