Strange leaf spots + Nitogen Toxicity?

[Cannanoob]

Hi Guys!

I’ve been reading this site for a while and everyone seems to be super friendly, so I thought I’d join and ask for some help with some problems I’m having.

I am growing a Sativa dominant automatic, and it is about 3 weeks into flower, growing in a 2x2x4 tent.
I'm using Plagron Light Mix for the substrate, feeding it with Plagron Alga Bloom (at 50% recommended dose), and I’m currently watering it with 1L of PH balanced demineralised water (after I discovered that my tap water is around 450PPM), every 3rd day or so.
I'm running a Viparspectra 300 at 18/6, and it’s in an 8L (~2Gallon) plastic pot with extra holes drilled into the bottom.
The temp averages around 23c in the tent and I try to keep the humidity at around 40%, but it is a struggle and it often dips a little below this.

Problem 1:
I am seeing small light yellowish spots on a lot of the leaves. They’re mostly on the lower ones, and they seem to be spreading:

I have checked for spider mites, giving it a good look using a microscope, but I couldn’t see any signs of bugs: no eggs, nothing at all on the underside of the leaves, no webs. And I do not think it is mildew or mould, because it does not look like any of the many photos of this I have seen, and it does not rub off or move when touched, in fact it seems to be inside the leaves.

So I thought that it was maybe a calcium deficiency due to the demineralised water I’ve started using, but I recall seeing the beginnings of these spots back when I was still watering with heavy/hard tap water…so maybe it is a type of leaf miner, or something like that?

Problem 2:
I also noticed that the leaves are a very dark green, and some are clawing at the ends.

From what I understand these are signs of nitrogen toxicity. But if this is the case, I will be completely mystified as to how it was caused. The Alga Bloom has an NPK of 3-2-5, and I have fed it to this plant only 3 times…is it possible that I have a nutrient lockout from the first couple of times that I watered it with the hard/high PPM water?

Maybe Im completely wrong with all of these guesses, but I thought it might help to mention what I’ve done/checked for/etc

Any thoughts or suggestions will be most appreciated!

Thanks!

 

[Mañ'O'Green]

@Cannanoob Welcome to AFN First off we need to see pictures in regular daylight (5000K) for diagnostics - turn off the grow lights. It looks like a lock-out from too much fertilizer. Your nutrients may be going in out of balance as well. In order for the plant to assimilate the nutrients it needs to flourish the elements need to be in the root zone in "Balance" to each other at the proper PH. That is often easier said than done.

This chart shows the needed relationship for those elements expressed as PPM of a liter (not EC). In order for a fertilizer to be in balance ALL of the elements must be present in the ranges displayed. It can be a really big range for many of them. This allows for different formulas based on the plants maturity. Lets just look at the top 3 for example NPK 100,30,100 - 250,50,300 - 180,40,200 are all combinations that are in balance 50,50,300 is out of balance and can cause lock-outs.

 

[saskraider12]

@Cannanoob Welcome to AFN First off we need to see pictures in regular daylight (5000K) for diagnostics - turn off the grow lights. It looks like a lock-out from too much fertilizer. Your nutrients may be going in out of balance as well. In order for the plant to assimilate the nutrients it needs to flourish the elements need to be in the root zone in "Balance" to each other at the proper PH. That is often easier said than done.

This chart shows the needed relationship for those elements expressed as PPM of a liter (not EC). In order for a fertilizer to be in balance ALL of the elements must be present in the ranges displayed. It can be a really big range for many of them. This allows for different formulas based on the plants maturity. Lets just look at the top 3 for example NPK 100,30,100 - 250,50,300 - 180,40,200 are all combinations that are in balance 50,50,300 is out of balance and can cause lock-outs.

View attachment 1280293

Hi Guys!

I’ve been reading this site for a while and everyone seems to be super friendly, so I thought I’d join and ask for some help with some problems I’m having.

I am growing a Sativa dominant automatic, and it is about 3 weeks into flower, growing in a 2x2x4 tent.
I'm using Plagron Light Mix for the substrate, feeding it with Plagron Alga Bloom (at 50% recommended dose), and I’m currently watering it with 1L of PH balanced demineralised water (after I discovered that my tap water is around 450PPM), every 3rd day or so.
I'm running a Viparspectra 300 at 18/6, and it’s in an 8L (~2Gallon) plastic pot with extra holes drilled into the bottom.
The temp averages around 23c in the tent and I try to keep the humidity at around 40%, but it is a struggle and it often dips a little below this.

Problem 1:
I am seeing small light yellowish spots on a lot of the leaves. They’re mostly on the lower ones, and they seem to be spreading:
View attachment 1280173
View attachment 1280174
I have checked for spider mites, giving it a good look using a microscope, but I couldn’t see any signs of bugs: no eggs, nothing at all on the underside of the leaves, no webs. And I do not think it is mildew or mould, because it does not look like any of the many photos of this I have seen, and it does not rub off or move when touched, in fact it seems to be inside the leaves.

So I thought that it was maybe a calcium deficiency due to the demineralised water I’ve started using, but I recall seeing the beginnings of these spots back when I was still watering with heavy/hard tap water…so maybe it is a type of leaf miner, or something like that?

Problem 2:
I also noticed that the leaves are a very dark green, and some are clawing at the ends.
View attachment 1280175
From what I understand these are signs of nitrogen toxicity. But if this is the case, I will be completely mystified as to how it was caused. The Alga Bloom has an NPK of 3-2-5, and I have fed it to this plant only 3 times…is it possible that I have a nutrient lockout from the first couple of times that I watered it with the hard/high PPM water?

Maybe Im completely wrong with all of these guesses, but I thought it might help to mention what I’ve done/checked for/etc

Any thoughts or suggestions will be most appreciated!

Thanks!

i don't know very much, but that doesn't look like spider mites. I had a similar looking problem due to low humidity. My tent was in the 30% range and the plants did not like that. Once I bought a humidifier and got the humidity up to 50%, the problem went away.

 

[Cannanoob]

@Cannanoob Welcome to AFN First off we need to see pictures in regular daylight (5000K) for diagnostics - turn off the grow lights. It looks like a lock-out from too much fertilizer. Your nutrients may be going in out of balance as well. In order for the plant to assimilate the nutrients it needs to flourish the elements need to be in the root zone in "Balance" to each other at the proper PH. That is often easier said than done.

This chart shows the needed relationship for those elements expressed as PPM of a liter (not EC). In order for a fertilizer to be in balance ALL of the elements must be present in the ranges displayed. It can be a really big range for many of them. This allows for different formulas based on the plants maturity. Lets just look at the top 3 for example NPK 100,30,100 - 250,50,300 - 180,40,200 are all combinations that are in balance 50,50,300 is out of balance and can cause lock-outs.

View attachment 1280293

Thanks @Mañ'O'Green
Yeah, sorry about the quality of the pics. I will take some proper ones as soon as I can (its a stealth grow, so need to pick the right time).

And thanks for the info and the chart. Lots to think about there...
It seems that the nutrients that I am feeding are out of balance to begin with, and/or there is a factor in my environment somewhere that is creating this problem. Either way, I need to determine what it is so I can avoid repeating this mistake. I'm interested to understand how it has happened so quickly / after only a small number of feeds, too.

 

[Cannanoob]

i don't know very much, but that doesn't look like spider mites. I had a similar looking problem due to low humidity. My tent was in the 30% range and the plants did not like that. Once I bought a humidifier and got the humidity up to 50%, the problem went away.

Wow, that is really interesting to hear, thanks @saskraider12
Unless the tent is full, I am constantly struggling to maintain 40% humidity. It keeps dropping down to 35-37%, and I do not know how low it gets at night because my humidity meter / thermometer does not tell me the highs and lows over the last 24h period - I plan to invest in a better one, actually.

So it could potentially be dropping down to around 20% overnight for all I know, and I've been wondering how this might affect growth and development...

 

[saskraider12]

Wow, that is really interesting to hear, thanks @saskraider12
Unless the tent is full, I am constantly struggling to maintain 40% humidity. It keeps dropping down to 35-37%, and I do not know how low it gets at night because my humidity meter / thermometer does not tell me the highs and lows over the last 24h period - I plan to invest in a better one, actually.

So it could potentially be dropping down to around 20% overnight for all I know, and I've been wondering how this might affect growth and development...

if you can't afford a humidifier, I have heard people say they put a bucket of water in the tent with a towel hanging above it half way submerged in the bucket. I guess the towel wicks up the water and can increase the humidity. You could try that and see if it raises the humidity and fixes those spots.

 

[NorthernLights_420]

I would invest in a humidifier for winter. And a dehumidifier for summer. It usually high humidity summer and low humidity winter. Unless your living in a desert then you wud have low humidity all the time. But I live in Michigan. Now its winter here so low humidity. I don't use a humidifier as I have a tent to keep my environment dialed in. I run my dehumidifier all the time. It turns on as it needs too so the humidity dont get too high. I gotta empty my dehumidifier in the morning and at night. I want to get a short hose to just drain it in a drain which will be less work. Just havent bought a small hose yet to do it so for now I'm doing it manually.

 

[Cannanoob]

if you can't afford a humidifier, I have heard people say they put a bucket of water in the tent with a towel hanging above it half way submerged in the bucket. I guess the towel wicks up the water and can increase the humidity. You could try that and see if it raises the humidity and fixes those spots.

Thanks. I have been keeping pots of water in the tent, as well as hanging a wet towel, and it hasn't seemed to be doing much. Your suggestion of having a towel half submerged in some water sounds like it might be more effective. I'll try that. Cheers!

 

[Cannanoob]

I would invest in a humidifier for winter. And a dehumidifier for summer. It usually high humidity summer and low humidity winter. Unless your living in a desert then you wud have low humidity all the time. But I live in Michigan. Now its winter here so low humidity. I don't use a humidifier as I have a tent to keep my environment dialed in. I run my dehumidifier all the time. It turns on as it needs too so the humidity dont get too high. I gotta empty my dehumidifier in the morning and at night. I want to get a short hose to just drain it in a drain which will be less work. Just havent bought a small hose yet to do it so for now I'm doing it manually.

Yeah, I think I will invest in a small humidifier, it sounds like I need one. This issue goes away when the tent fills up more and more (e.g. during flowering it is usually between 45-50%), but at the early seedling stages low humidity is a constant problem. And given how crucial it is that autoflowers aren't stunted during vegetation stage, it seems like I'm shooting myself in the foot by not having one.

I've been thinking of getting one for a while but the reason I haven't is because my tent is very small and I don't have too much room. This means that I can only really fit a small one, and they usually only have a tiny reservoir and no ability to set a desired RH level. Also, Im a little concerned about the mist blowing into my growlight, which has vents on it and may cause issues with the circuit board over time, but maybe I'm overthinking it a little too much.

@NorthernLights_420 When you say "I don't use a humidifier as I have a tent to keep my environment dialed in." How are you doing this? I'm surprised to hear that you only need a dehumidifier, especially in winter. Do you have a massive tent full of girls in different stages?

 

[NorthernLights_420]

Yeah, I think I will invest in a small humidifier, it sounds like I need one. This issue goes away when the tent fills up more and more (e.g. during flowering it is usually between 45-50%), but at the early seedling stages low humidity is a constant problem. And given how crucial it is that autoflowers aren't stunted during vegetation stage, it seems like I'm shooting myself in the foot by not having one.

I've been thinking of getting one for a while but the reason I haven't is because my tent is very small and I don't have too much room. This means that I can only really fit a small one, and they usually only have a tiny reservoir and no ability to set a desired RH level. Also, Im a little concerned about the mist blowing into my growlight, which has vents on it and may cause issues with the circuit board over time, but maybe I'm overthinking it a little too much.

@NorthernLights_420 When you say "I don't use a humidifier as I have a tent to keep my environment dialed in." How are you doing this? I'm surprised to hear that you only need a dehumidifier, especially in winter. Do you have a massive tent full of girls in different stages?

I have a 4x4 and a 8x4 tent. My watering usually brings my humidity up. And the dehumidifier brings it down if it is too high. Do you have an extraction fan or intake fan? If so that cud be causing your humidity to be lower. If space is an issue hang a wet towel off a top bar in your tent like others suggested. Save money on a dehumidifier if it works.