Test Your Diagnostic Skills

[Sirius]

Hi, I have a problem that has been ongoing with my plants for the last couple weeks now. There has been a lot of different approaches I've tried over the course of this time in attempt to keep it from getting worse, but it still seems to be advancing, perhaps a bit more slowly. Also, this is our first real grow, so we're still learning how to take care of everything. What I'd like to do is post a comprehensive set of pictures of all of these plants (which all show the same symptoms to some degree), and explain the general specifics of the environment, leaving it a little more open for ya'll to go with your instincts and tell me what you think the problem is. I'll be basing my approach going forward on what is said here, as I've tried a lot and really need to get this to stop before it really starts affecting the health of the plants as they begin flowering.

Now, they are growing in coco, which was well-flushed and pH adjusted from the beginning. They've been in 3.4 liter pots of it, and had been for a couple weeks before the problems started showing up. They are being fed with coco-specific nutrients, usually with a dose of calcium and a dose of magnesium. The water is from tap, but we usually try to leave it sitting at least a day for the chlorine to evaporate. The water has always been adjusted to 5.8. Watering has been every other day or sometimes every day. Also, the plants were in a bigger rockwool cube when they were transplanted - I didn't know at the time that this was a no-no. It had been a couple weeks since this transplant, though, before the problems really began to develop, but I still am suspicious of the crappy stuff.

They are underneath a 600 watt HPS. Right now they are probably about a foot away from it. There was a couple of days when the temperatures were reaching 90F, but this was quickly adjusted to make sure that it stays around 75F. The problem has been advancing since this time, which would seem to rule out heat stress. The humidity is pretty low due to the air conditioning, but the coco is always kept very moist.

The plants are about six weeks old or so, and have been on 12/12 for three days now. The roots are finally really showing up on the sides of the pot, and will be transplanted into 16 liter pots as soon as sex is verified, which should be here in the next couple days.

Anyways, that is the general situation. Please tell me what you think, feel free to ask any questions if there's something I can say that will help. Basically, though, I'm just looking for an intuitive feel on what this could be, to help confirm or deny my suspicions. So, this is kind of a test for everyone. They really seem healthy beyond these leaf edges burning like this. Here's the pictures of all of the plants. I think the flash might make them look less green in the top shots than they actually are, which is noticeable when compared to the side shots.


Greenhouse's Arjan's Haze #3:


AH3 1

AH3 2

Critically Smashed (Critical Mass x White Rhino):


CS 1

CS 2

CS 3

CS 4

Mandala's White Satin:


WS 1

WS 2

WS 3

WS 4

WS 5

Thanks for your help!

 

[maryj315]

i am no expert but since you have suspicion i will give a opinion just for thought until somebody who you trust chimes in. although i have read some of your posts and i think you would figure it out for yourself in no time, but i think it is nute burn,ph fluctuation or using tap in coco i read you need a 50/50 mix or straight ro with cal mag. have a good day

 

[DIGITALHIPPY]

looks like an intresting situation, i see mag and calcium defs. yet the lower leafs look burnt/rootbound it could also be a ph flux or from a incident of dehydration.

id sugest getting sensical to use with what im assuming is RO or clean-ass tap.

water? what kind?
nutes? what kind?
fans? what kind?

there not too bad really. id sugest a foliar (2-3 min before the light turns off) of epsom salts (1tsp/liter) just soak the plants leafs with it. should make-em green-up alot more.

 

[Sirius]

Hey, thanks for replying. I'm looking for every input from every angle on this that I can get, so don't worry about feeling reluctant about sharing your perspective on the matter.

I'd comment on my take on what you think it might be, but I'd rather wait because I don't want to offer more of my thoughts on what and why it might be, so I don't influence anyone else's ideas before they say.

 

[Sirius]

looks like an intresting situation, i see mag and calcium defs. yet the lower leafs look burnt/rootbound it could also be a ph flux or from a incident of dehydration.

id sugest getting sensical to use with what im assuming is RO or clean-ass tap.

water? what kind?
nutes? what kind?
fans? what kind?

there not too bad really. id sugest a foliar (2-3 min before the light turns off) of epsom salts (1tsp/liter) just soak the plants leafs with it. should make-em green-up alot more.

Hey, very interesting reply. Let me get back to this in a little while with some more information, tied up at the moment.

 

[MedResearcher]

I use to use a PH of 5.8 in my CoCo as well, until someone suggested aiming for 6.1


So now I am always at 6.1 or close to it maybe .1 off


Since I changed my PH which was maybe a half a year ago, I stopped seeing defs and lock outs. Getting my Nute line dialed in, and getting rid of all the additives helped alot as well.


Although 5.8 isnt extremely low so I dont think it would be causing a lock out. At the same time CoCo specific nutes +cal mag +tap water should be a ton of Mag and Cal, so there shouldnt be a defficency, so I would guess its a lock out.




I would consider raising your PH to aim at 6.1, and let everyone know the specific nutes and the EC of your tap water, as well as EC after you mix in
the nutes. That way you get a better answer, instead of a bunch of guesses.


Also make sure when you water, you give it a ton of runoff. The more runoff the better, gets all the excess salts out of the medium. Salt build up is a for sure way to get a lock out. Especially if the temp is 90 degrees the medium will dry fast leaving alot of salt behind.


Fixing the tempature was a good start, hopefully someone else will chime in with a better fix.

MR^^

 

[Sirius]

The reason I didn't get too specific about the different dosages of nutrients and everything is because over the last couple of weeks, different things have been tried out with some time to see how the plants would respond. I've been a little more general about it all because I'm actually looking for a bunch of guesses, very curious as to how different people read the signs that the plant is giving, supplemented with some basic info about the situation.

That's interesting about the 6.1 pH. I've been considering if it would be a good idea to move up to 6.0. I think this is something we may change. This way, if the pen is inaccurate up or down a few points, its in a good range to allow that discrepancy as well. As for the runoff, we give them 1L of water with nutrients, and there does seem to be a fair bit of runoff. There have been times throughout this period that we have flushed it out with 2L of water, and then given them their nutes. I think maybe we will start this again, because it would be a good idea to get everything out of the coco that the plants aren't using. For 3.4L pots, would 2L of flushing water be enough? Once when we were very serious about flushing everything out to kind of reset everything (after we gave them far too much Ca due to a mislabel on the bottle, it said 1% CaO when it should have said 15%, found out later), we flushed 10L through each plant, 1L at a time. Maybe its time to try that out again as well.

Digitalhippy, I don't think they look that much lime in actuality, but I think the flash brought that out. If you look at the the side pictures, that green color is the way the plants look throughout. Anyways, the color getting more lime and some intervenial chloriosis has been going on throughout this period, but I think its been becoming less of a problem the last few days.

Its just tap water. The nutrients are Atami Coco A and B, and I have a bottle of Bionova MgO and a bottle of Bionova CaO. There is a 215cfm extractor fan pulling air through the cool-tube, and a regular oscillating fan that blows the air between the canopy and the cool-tube to help keep more heat away.

The last few days, we've been giving 2mL/L of the Coco A&B, .75mL/L of the MgO, and .25mL/L of the CaO. I don't have an EC meter, but I profiled the nutrients at CannaStats (didn't have the net weight or liquid volume though, which means it could be understated by as much as 25%). When you add up the ppm of everything, this is what it would be:

N 142
P 42
K 214
Mg 72
Ca 100

My thinking as of late has been that its nutrient burn. When you mention the possibility of dehydration, I think this played a part in the beginning. I think the problem started when there was a magnesium lock-out due to the excess Ca due to the mislabel, and then, when the temperatures were reaching that high under the HPS, the burning started because of the subsequently weaker edges of the older leaves, compounded by the low humidity. The humidity is still low, the temperatures stay right around 26C/85F, but I would think that the coco stays wet enough that the burning isn't due to dehydration. A lot of the burnt edges don't have much of any intervenial chloriosis around them anymore.

Anyways, thanks for all the time and help everyone. I think I'll take some more pictures soon that give some close-ups of the leaves and everything like that, to help show what is happening.

 

[metamorf]

Looks like pH is fluctuating, locking out micros in the process.

 

[Sirius]

I've taken some close-ups of leaves from all of the plants to help show what is going on here. Again, its only occurring with older growth, although the tiny leaves forming from the growth tips seem a very yellow-green. Starting to foliar spray and they will be getting a vigorous flushing in a little while. Hopefully this can be straightened out. No epsom salts around here for the foliar spray, so we're working with our bottle of bionova magnesium. I'll keep this going until some kind of conclusion or consensus on the matter is established. Any input is more than welcome. Thanks everyone for what's been posted so far.

 

[Sirius]

Also, forgot to mention, when we flush and feed tonight, we'll be adjusting the pH up from 5.8 to around 6.2. The pH is the one thing that has remained constant all of this time, and based on what's been said here and the process of elimination, it seems to be the likely culprit. I'm praying it is, because I'm fucking sick of this!

 

[Sirius]

From H3ad's Plant Nutrition and Visual Diagnosis:

Potassium
Type: primary macronutrient
Necessary for formation of sugars, starches, carbohydrates, protein synthesis and cell division in roots and other parts of the plant. It helps to adjust water balance, improves stem rigidity and cold hardiness, enhances flavor and color on fruit and vegetable crops, increases the oil content of fruits and is important for leafy crops. Just as with P, K uptake is highest during the earliest growth stages. K is associated with sturdy stems and resistance to disease in plants.
Deficiency symptoms: Leaf margins turn chlorotic and then necrotic; scattered chlorotic spots often occur on the leaves, and these spots may later turn necrotic. K deficiencies sometimes show on indoor plants even when there is apparently enough supplied for normal growth. Often, potassium-deficient plants are the tallest and appear to be the most vigorous. Starting on the large lower leaves, the tips of the blades brown and die. Necrotic areas or spots form on the blades, particularly along the margins. Sometimes the leaves are spattered with chlorotic tissue before necrosis develops, and the leaves look pale or yellow.
High amounts of K can cause Ca, Mg, and N deficiencies. High sodium can cause K deficiency.
High soil Mg can reduce K uptake, but it seems to occur only when the soil Mg saturation is in the range of 25% to 30%, or higher.
Numerous studies have looked at the possibility of using the K/(Ca + Mg) ratio to explain certain nutrition problems. While this ratio may be useful at some times, often there is no relationship between these cation ratios and crop performance.
High K levels can help against ammonium toxicity.
There is no evidence that K has a direct elemental toxicity. Excess K is more likely to be experienced first as an induced Mg deficiency. Next on the scale of probable high K damage signs might be induced Ca deficiencies

All right, I thought I'd make an update on this. We've spent the last week working on different things to figure out what the hell is wrong and to fix it. The first thing we did was flush out the 3.4 liter containers with 10 liters of water, which was adjusted to a pH of 6.3. We then fed with a half mL per liter of Atami Coco A&B. The next day we increased it to 1mL, and then the next day added a 1/4mL of their P/K booster.

The main thing of interest, though, is we had two plants that turned out to be male, so we figured it was time for some experimentation to help figure this out. The first thing we did was give the one a huge dose of Mg and the other a bigger increase in P/K when the others weren't getting any. The Mg plant had received some burning the next day from the large dose, but the intent was to see if the color that was missing would change, and it didn't, settling that it wasn't the problem.

The male with the P/K started to look more healthy, and the more lime green color of the leaves that you can see above started turning a healthy, dark green. Last night, we upped it to 1ml of P/K with the 1mL of A/B, and it looks even healthier, a nice dark green, with just a slight evidence of some burning from the dose, a different color of burn that the plants have been showing.

So today we'll be trying out a dose on the females that seems to be the real thing and sustain it for a couple days to see if it will finally solve this thing. I really feel like this will settle the issue. Here's a picture of a comparison between a leaf from the P/K male and one from one of the main group, both leaves pretty much the same age:

Thanks for the input on this everyone, I'm really hoping to bring this to a happy conclusion.