Yellow-brown crispy spots on fan leaves on 4 different strains.

Hello people.It's been about 10 days I have this problem and it seems it's getting worst gradually.I'm growing 4 different strains:Masterkush, Super Silver Haze, Ice Cream and Blue Cheese.


Here are some pictures:



And the most affected plant, masterkush:


I've switched to 12/12 5 days ago.I'm using a 400 watt HPS and it's 45cm away from tops.Not overwatering or underwatering, temps 27-29 C lights on and 20-21 C lights off.I've fed them twice with biogrow, 1/3-1/2 of minimum suggested dosage and ten days later I added biobloom, 1/2 of minimum suggested dosage.It's been a week since the last.I'm using tap water which I let it sit for 4-5 days prior to watering.I suspect that it's the water though because it's very hard.

I've been searching pretty hard and the symptoms look like potassium or phosphorus deficiency or light burn.Light burn seems unlikely because of the light distance.I can't check the ph but since I've fed them very lightly I don't think it's off.So what's your opinions?

def got a lock up there. what brand of soil? I would flush for the next waterings and when you do feed again I would drop that down to 1/4. i would also take a ph reading of your water, i know it has been sitting, before and after you add the nutrients. do you let the nutrients sit for the 4-5 days as well? good luck

Well i dont know but them leaves look a bit tough, dark green and crispy, as well as the obvious burnt bits. I would say 29celcius is at the max end for lots of strains and without Co2 run at 25celcius max. Some might disagree but always been what i aim for, lower temps would be a quick easy fix whilst considering possible deficiencies etc etc etc Peace

Dont you know MaryJanes a lesbian these days and dont have no 'boyfriend'.....

I doubt it's pH lock out as well, but just to rule that out is there any way you CAN check it? Looks to me to be a Potassium Deficiency. A P deficiency appears as a more well defined crisping from the leaf margins and curling/twisting. The first pic is classic K deficiency. Get them some fast acting K.
BTW, not everyone is familiar with all the NPK values of those "bottled nutes", so you may wanna give NPK values as well as name brands. Just a thought.

cacamal said:

def got a lock up there. what brand of soil? I would flush for the next waterings and when you do feed again I would drop that down to 1/4. i would also take a ph reading of your water, i know it has been sitting, before and after you add the nutrients. do you let the nutrients sit for the 4-5 days as well? good luck

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I bought the soil from a local store, no big brand but I remember buying it because it was lightly fertilized.I've used one more time with no problems.I didn't know I should let the nutrients as well, why is that?I shake the solution though.

Kingrow1 said:

Well i dont know but them leaves look a bit tough, dark green and crispy, as well as the obvious burnt bits. I would say 29celcius is at the max end for lots of strains and without Co2 run at 25celcius max. Some might disagree but always been what i aim for, lower temps would be a quick easy fix whilst considering possible deficiencies etc etc etc Peace

Dont you know MaryJanes a lesbian these days and dont have no 'boyfriend'.....

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hahahaha!
I can put the light higher but then it won't be intense enough.I'm waiting for the weather to get cool because it's still pretty warm.

Jack Harer said:

I doubt it's pH lock out as well, but just to rule that out is there any way you CAN check it? Looks to me to be a Potassium Deficiency. A P deficiency appears as a more well defined crisping from the leaf margins and curling/twisting. The first pic is classic K deficiency. Get them some fast acting K.
BTW, not everyone is familiar with all the NPK values of those "bottled nutes", so you may wanna give NPK values as well as name brands. Just a thought.

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I can't check the ph anytime soon.It also seems to me like a deficiency or, worst, a lockout but since I wasn't overfeeding or underfeeding (i think), it troubles me.The biogrow contains 8-2-6 and the biobloom 2-6-3.5

Did you get any nutes on the leaves. I slosh my water around alot and wreck a few fans leaves that way

Duku said:

Did you get any nutes on the leaves. I slosh my water around alot and wreck a few fans leaves that way

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No I was careful about it also.I've made a solution and added alg-a-mic a little less than half the minimum dose.It contains NPK 0.1-0.1-0.1 plus calcium (0.2) and magnesium (0.1).I was thinking to feed the three of them and flush the masterkush.

That's a pretty mild NPK, I'd give them a full strength dose. If it were like 20-20-20, I'd be cutting back, but that's really mild fert at those values. Your pH would have to be pretty far out of whack to create that kind of a problem in soil. Like I said, I doubt it's lock-out, and I believe you have a definite K deficiency. Maybe P too, but for sure K.

Jack Harer said:

That's a pretty mild NPK, I'd give them a full strength dose. If it were like 20-20-20, I'd be cutting back, but that's really mild fert at those values. Your pH would have to be pretty far out of whack to create that kind of a problem in soil. Like I said, I doubt it's lock-out, and I believe you have a definite K deficiency. Maybe P too, but for sure K.

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OK tomorrow morning I will give them 1/2 of the dose and check how they're going.

It shouldn't progress any more after you feed them something. I'd still go with full strength of that, but that's me. The crispy stuff, necrotic tissue, will not come back. It's dead, but look for the new growth in a couple of days. It should look OK.

Dont look deficient to me unfortunatly but there are those who would like to see you add ferts, why not should help.
Just out of intrest how many days are you hitting 29c without co2. Peace

maybe heat stress. try gettin one of those thermometers that record the "HI" of the day. make sure your temp isnt tryin to be sneaky

Kingrow1 said:

Dont look deficient to me unfortunatly but there are those who would like to see you add ferts, why not should help.
Just out of intrest how many days are you hitting 29c without co2. Peace

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5 hours a day, at least, the temp is 28.5-29 C.I ordered ph strips, they should be here by Monday.I also found a ph-down liquid I bought 3 years ago when I tested the tap water and it's ph was 7.5-8, I just remembered that.So today I added the ph-down to the solution and I fed them, fingers crossed!

Grow mo said:

maybe heat stress. try gettin one of those thermometers that record the "HI" of the day. make sure your temp isnt tryin to be sneaky

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My thermoterer records the max and the min of the last 24hrs.The temperature never exceeds 29C and most of the day is about 28-28.5.Right now (11.00) the temp is 27C and the light starts at 10.00.The minimum at night drops to 20-21C.

Ok so reguardless of pH and deficiencies i would definatly bring the temps down to 25celcius max, indoor i wouldnt go over this really but some might, safe bet is sort the temps out as well.

Your water pH is fine and adding ferts shouldnt drop it that much, ph or dont ph the water and feeds, for me i dont bother and it makes little difference, lime in the soil can make a big difference ,depending on soil and situation.

Forget the pH just add lime next grow or topdress this one. Most of all id sort the temps out, dose anyone think running at 29c and thereabouts is a little high and can bring about heat stress?? Peace

Kingrow1 said:

Ok so reguardless of pH and deficiencies i would definatly bring the temps down to 25celcius max, indoor i wouldnt go over this really but some might, safe bet is sort the temps out as well.

Your water pH is fine and adding ferts shouldnt drop it that much, ph or dont ph the water and feeds, for me i dont bother and it makes little difference, lime in the soil can make a big difference ,depending on soil and situation.

Forget the pH just add lime next grow or topdress this one. Most of all id sort the temps out, dose anyone think running at 29c and thereabouts is a little high and can bring about heat stress?? Peace

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Lime drops the ph right?How much should I use?About the temps...outside right now we've got 25C, in my growroom 28.8C, so I can't do much about it.Next week the weather will be cooler.

I can only talk about my situation with my soil and lime requirements, it was only in respose to you saying pH nothing else. I only cared that temps of 29 for extended periods and many susequent days could quite easily bring about heat stress and one step at a time i.e. dont go in changing everything, work with the obvious and easiest then go for the others one by one if problem remains unresolved. Peace

Lime will tend to RAISE pH. It's used as a buffer to raise and stabilize the pH of acidic soil, and to buffer soil-less mixes.

I've got updates.Ph is fine.I watered with ph of 7.7 and the run off ph was 7.So soil's ph would be around 6.5 which is ideal.Problem seems to get worse in 1 plant while in others it's quite stable.I think that leads to defficiency...any ideas?

I might be wrong but: pH doesn't work in a linear manner, it is a logarithmic measure of H+ ion concentration. So you can't say mix 50/50 pH 5.0 and 6.0 and be left with pH 5.5.
Your water's pH seems high, I mean maybe your soil needed some additional buffering capacity to start with, but by now you would think it would be ok to water with pH 6.5?
I don't use soil personally, so might be shit advice. But I have been told that many nutrients are locked out around 7 and above, so this could be a source of your woes.

Good luck with the girls.