Leaf discoloration and necrosis

Hi Everyone

I am on day 20 of 12/12 and have been having some issues with leaf discoloration (yellowing) followed by necrotic spots, followed by dry crispiness. My strain is Kali Mist with a flowering time of 70-95 days.

The problem started with the older lower growth and was very intermittent. The issue has now moved up to my mid-growth and I am now seeing the beginning signs on the top growth.

I have researched everything I can find, and to be honest, most of the photos of these problems look the same to me (poor eyesight). I initially thought it was Magnesium deficiency, but a dose of epsom salts in the last watering has shown no improvement. I have also foliar sprayed epsom salted water 10 minutes before the light cycle starts.

I'm now concerned it may be a Calcium deficiency or I have over fertilized...? I hope it isn't the latter as I am using nutes only every second watering, and I've been really gentle about easing into fertilizer. Or, is this just the plant depleting Nitrogen normal with flowering? If this is Nitrogen, should I give her a dose of the veg nutes considering I have at least 50 more days of flowering to go?

My medium is 5 parts good quality organic soil to equal parts pearlite plus two parts sterilized farmyard manure. My pH is consistently at 7.0. Lighting is 400W HPS (MH during veg). Temps have been okay and <82F the whole grow (lights on) and 69F with lights off.

Nutrients are General Hydroponics FloraNova Grow and Bloom.

The odd yellow leaf did creep up during veg, but I dismissed it as normal. This more widespread problem has been about a week developing.

I have also noted downward curl (the "claw" in the last pic). I'm hoping this isn't heat stress.

Photos attached. Many thanks for assisstance.

tryed flushing? could be nute burn, every other watering is alot no?

im having this same issue actually im pretty sure its related to K def. i myself cant really get a definitive answer what it is. it could be K def. or lack of Cal/Mag those are the two most common solutions. this seems to also be the most common problem to growing indoors.

Well, I am in the same boat. I have been trying to no avail for the last month to put an end to these yellowing leaves. Overall my plants look healthy just like yours do, but my older growth gets sporadic yellow leaves and necrotic spots. They started at the bottom third and are working their way up just like yours. I am growing outdoors where temps reach 110F. I also have very low humidity. I really don't think it would be a heat thing since I'd think the top of the plant would be more effected than the bottom. I think it must be a nutrient thing. Trying to diagnose it myself, I thought either cal/mag or k deficiency.

A few weeks ago I did a full flush of my raised bed which didn't help anything. Actually, after my flush my leaves started to cup and I started to get these necrotic spots. I am starting to think I have salt buildup or something that is causing some nutrient to get locked out. I stopped all feeding several weeks ago as I thought some damage might be due to nute burn, but like you I have been very sparing with the nutes. I am very lost. I tried epsom salt by watering and foliar feeding with it. No improvement. Very frustrating.



What do you think? Look similar? I'm certainly not as far along when it comes to flowering, but some respected growers on here state that you should maintain green leaves throughout your entire grow, since leaves produce buds. I am getting back on the nutes now at 1/4 strength every other watering (I currently water every other day).

The claw thing is usually from over watering, no? I have the cupped leaves, you have the claw leaves. It doesn't seem to matter how much or how little I water, I can't get rid of the cupping. WTF

it does look VERY similar, i have been giving more K i upped the molasses but over the past week the issue has gotten nothing but worse, have you tried cal/mag? im cosidering taking this step today as nothing else (flushing and replacement nutes) has helped and it seems this is the other solution for most people with this problem. the plant is curling up also on certain leaves and cupping down on others.

lvnv said:

Well, I am in the same boat. I have been trying to no avail for the last month to put an end to these yellowing leaves. Overall my plants look healthy just like yours do, but my older growth gets sporadic yellow leaves and necrotic spots. They started at the bottom third and are working their way up just like yours. I am growing outdoors where temps reach 110F. I also have very low humidity. I really don't think it would be a heat thing since I'd think the top of the plant would be more effected than the bottom. I think it must be a nutrient thing. Trying to diagnose it myself, I thought either cal/mag or k deficiency.

A few weeks ago I did a full flush of my raised bed which didn't help anything. Actually, after my flush my leaves started to cup and I started to get these necrotic spots. I am starting to think I have salt buildup or something that is causing some nutrient to get locked out. I stopped all feeding several weeks ago as I thought some damage might be due to nute burn, but like you I have been very sparing with the nutes. I am very lost. I tried epsom salt by watering and foliar feeding with it. No improvement. Very frustrating.

View attachment 1071634View attachment 1071633View attachment 1071635

What do you think? Look similar? I'm certainly not as far along when it comes to flowering, but some respected growers on here state that you should maintain green leaves throughout your entire grow, since leaves produce buds. I am getting back on the nutes now at 1/4 strength every other watering (I currently water every other day).

The claw thing is usually from over watering, no? I have the cupped leaves, you have the claw leaves. It doesn't seem to matter how much or how little I water, I can't get rid of the cupping. WTF

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Sorry to hear you are having trouble too. This looks like exactly the same problem I am having.

I think the manure in your media mix is the problem. Sterilized or not it contains a lot of salts which could cause symptoms like this. Any manure should be well composted and at least a year old to be safe. This looks like a nute burn. The flush should help and the other leaves look plenty green so I would take it easy on the nutrients and use diluted formulas or just use water until you see the tips of the branches start to turn light green. Usually when the older lower leaves yellow it is a sign that it is time to fertilize because the N is being used up, but in this case it looks like salt burn because the rest of the foliage is not showing any deficiency.

If the epsom salts did not solve this marginal chlorosis this is not a MG problem.

Another possibility is the manure is not fully composted and is giving off ammonia vapors from the nitrification process.

carokann said:

tryed flushing? could be nute burn, every other watering is alot no?

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yeah i would flush and probably not do any nutes at all at least for a few weeks to see if this has any impact.
- soil npk should be around 20-10-10 for vegging and then up the k once it gets into flowering and try not to add any nitrogen as the soil should still have plenty left and it doesn't require as much.

just cut off the dieing/dead leave bunches.

whats the humidity range?

might be mistaken but i believe the most optimal ph is 6.5.

also, do yourself a favor and grab a soil moisture meter to aid in watering. generally every 1-2 days is sufficient for watering, but you want to make sure it has a chance to dry out for the most part in between waterings.

lvnv said:

The claw thing is usually from over watering, no? I have the cupped leaves, you have the claw leaves. It doesn't seem to matter how much or how little I water, I can't get rid of the cupping. WTF

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is your claw moist or dry

its also a good idea to wait about a week between any given change in the plants uptake to give the plant a chance to settle.

victhaog said:

the plant is curling up also on certain leaves and cupping down on others.

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this can be caused by frequent changes that take a while for the plant to show its effects.
try to give it at least a week between a single change until problems are weeded out.

I am having the same problem as well although I have a flood and drain setup.

The factors I think might be affecting my grow are white pots that allow algae growth, and/or nutrient balance.

I can keep the plants looking healthy for 5-9 days and then I have to change the tank to prevent deterioration. I like the Cal/Mag idea since I am using RO water. Hopefully we can all figure out what is going on.

The white pots are the problem. I worked in a nursery and we used white pots for some perennials and they all grew algae between the pot and soil ball and if the plants didn't sell rapidly the algae and moss would use up the nutrients and moisture and kill the remaining plants.

pointswest said:

The white pots are the problem. I worked in a nursery and we used white pots for some perennials and they all grew algae between the pot and soil ball and if the plants didn't sell rapidly the algae and moss would use up the nutrients and moisture and kill the remaining plants.

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I have pulled 2 plants and 1 rootball was entirely green on the outside and the other partially green. I think you are right that it might be one of the major problems.

pointswest said:

I think the manure in your media mix is the problem. Sterilized or not it contains a lot of salts which could cause symptoms like this. Any manure should be well composted and at least a year old to be safe. This looks like a nute burn. The flush should help and the other leaves look plenty green so I would take it easy on the nutrients and use diluted formulas or just use water until you see the tips of the branches start to turn light green. Usually when the older lower leaves yellow it is a sign that it is time to fertilize because the N is being used up, but in this case it looks like salt burn because the rest of the foliage is not showing any deficiency.

If the epsom salts did not solve this marginal chlorosis this is not a MG problem.

Another possibility is the manure is not fully composted and is giving off ammonia vapors from the nitrification process.

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Excellent advice and explanation - thank you very much!

My manure was fully composted, and I even allowed my soil mix to settle for two weeks prior to germination....but I hear you on the other risks associated with this additive.

Xenosis said:

whats the humidity range?

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Low = 40%; high=60%

Xenosis said:

also, do yourself a favor and grab a soil moisture meter to aid in watering. generally every 1-2 days is sufficient for watering, but you want to make sure it has a chance to dry out for the most part in between waterings.

is your claw moist or dry

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I use a moisture meter and cycle between every 2 to every 3 days to water depending on the meter. The "claw" leaves actually feel perfectly normal, just the shape seems off. Moisture in the leaf seems okay.

Xenosis said:

its also a good idea to wait about a week between any given change in the plants uptake to give the plant a chance to settle.this can be caused by frequent changes that take a while for the plant to show its effects. try to give it at least a week between a single change at least until problems are weeded out.

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Thank you for the excellent info/advice.

4north9 said:

Low = 40%; high=60%

I use a moisture meter and cycle between every 2 to every 3 days to water depending on the meter. The "claw" leaves actually feel perfectly normal, just the shape seems off. Moisture in the leaf seems okay.

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ok, i would try to keep humidity closer to 60, but it doesnt sound like a watering problem.

most likely nute related like pointswest was saying, also:

Uncle Ben said:

Being that it is so short lived, only if there is a deficiency.

The N in lower leaves will be sacrificed by the plant to newer growth. Very low light levels will also induce leaf drop - your call.

I guarantee if you're using one of the typical Bloom foods, exclusively, you'll lose lower leaves and more as the symptom/result moves up the plant. What these manufacturer's are conveniently forgetting to tell you (and manufacturers of "cannabis specific" foods are the worst) is that it's leaves that produce flowers/fruit, not their plant food. You can use all the Bloom food you want, but you progressively start losing the very unit that produces bud and you're in deep shit. - https://www.rollitup.org/marijuana-plant-problems/150004-plant-moisture-stress-symptoms-solutions-14.html

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