Help! Pale yellow leaves with brown spots

[Luckydawg]

Hi, cant seem to figure this out. My friend's first time LED soil grow with clones of AK 48 in 5 gal pots. Leaves are very light yellow with brown spots on mostly older leaves. Stunted growth. Have treated with Actinovate for possible pests in soil but problem getting worse. None of the disease or nute difficency pix quite match right. Any help appreciated.

 

[Luckydawg]

Also, have checked ph and it seems neutral.

 

[Emilya Green]

Also, have checked ph and it seems neutral.

neutral? you mean 7.0 pH? If so, that could very well be the problem... the usable range in soil is 6.3-6.8. It would be helpful to me to be able to see a picture of the entire plant, complete with the damage, so I could see where it was occurring. Did it start at the bottom of the plant and work up, and is it all over the plant now? Also, quit plucking those damaged leaves. The plant is missing some vital nutrient, for some reason. That leaf damage is the plant's way of surviving this, it is using those leaves as emergency storehouses for whatever this nutrient is, and it is absorbing them into the system so as to be able to supply the new growth with what it needs. When you pluck one of these leaves that are being used in this emergency, your frustrated plant has no choice but to start doing the same thing to the next set of leaves up. By plucking leaves, you have accelerated this process... it might make you feel better not seeing the damage, but your are doing your plants no favors by removing them.
Along with pH, I always suspect watering practices with new growers of weed. How often do you water, and do you let them dry out completely all the way to the bottom before you water each time?

 

[fanleaf]

neutral? you mean 7.0 pH? If so, that could very well be the problem... the usable range in soil is 6.3-6.8. It would be helpful to me to be able to see a picture of the entire plant, complete with the damage, so I could see where it was occurring. Did it start at the bottom of the plant and work up, and is it all over the plant now? Also, quit plucking those damaged leaves. The plant is missing some vital nutrient, for some reason. That leaf damage is the plant's way of surviving this, it is using those leaves as emergency storehouses for whatever this nutrient is, and it is absorbing them into the system so as to be able to supply the new growth with what it needs. When you pluck one of these leaves that are being used in this emergency, your frustrated plant has no choice but to start doing the same thing to the next set of leaves up. By plucking leaves, you have accelerated this process... it might make you feel better not seeing the damage, but your are doing your plants no favors by removing them.
Along with pH, I always suspect watering practices with new growers of weed. How often do you water, and do you let them dry out completely all the way to the bottom before you water each time?

Really red stems too! looks like phosphorus deficiency to me. Phosphorus is easily uptaken anywhere from a 6.5-7.5ph so I'm not sure. I think I would recheck soil ph because the rest of the leaf is a really light green as well so it could also be showing Nitrogen deficiency as well.

I think you have a ph issue. What are you testing with and how?
I would flush with at least 15 gallons of water and to the last 1-1.5 gallons add new nutes.

 

[Luckydawg]

we are using pretty basic test so not possible to tell exact ph. Dont think they were over watered. Apologize for follow up pic which is on its side but gives a general idea of the problem. Will stop pull off sick leaves!

 

[Luckydawg]

BTW, thanks for taking a look at this, the closest pics I could find seem to indicate manganese deficiency???

 

[Luckydawg]

@fanleaf, regarding the light color of the leaves, the photo actually makes them look darker green than they are so the bleached out color is worse in real life.

I don't think its over water but is this kind of damage indicative of that mistake??? I"m thinking of runing over to garden shop to get some kind of standard fert to spray on theleaves, which was what I saw recommended for manganese dif.

Opinions?

 

[Emilya Green]

instead of spending all that money on this, just mix up some epsom salts 1 tbs / gallon and spray that on there. If it is magnesium you will see a pretty rapid deepening of the green, but nothing you can do now will bring the damaged areas back... they are gone.

Don't discount overwatering either. You can easily overwater by watering too often, it has very little to do with how much you give them each time. After seeing your entire plant though, and seeing equal damage all over the plant, I am even more convinced that this is a non-mobile nutrient problem, probably due to pH. This eliminates nitrogen, potassium and phosphorus, and phosphorus is not even in the picture really at this point in its life... that isn't till later in flower.

I am convinced that this is a trace mineral problem, most likely magnesium, most likely because your pH is too high. Figure out a way to get every liquid you give this plant to be at around 6.5 pH and I believe your problem will stop progressing. Also keep in mind that spraying something on the plant is a band-aid... it is not a permanent solution to this problem.

 

[fanleaf]

What nutes are you feeding her? What soil is it?

If you are feeding nutes she's not getting them. Flush her with 15 gallons of water asap and add new nutes to the last gallon or 2. This was not caused by over watering. I'm almost sure you are experiencing lockout. Either way a flush won't hurt her but I'm sure the symptoms will stop directly after the flush followed by new nutes.

I highly doubt your ph is 7+

Magnesium uptakes at 7 and even higher just fine

I'm almost sure your in fact experiencing lockout due to low ph. I bet you have salts deep in the soil that need flushed. If the top of the soil ph tests at 7.0 that does not mean that deep in the root zone towards the bottom of the pot there is not built up salts and a ph way way lower. Hell, I had 6.9 at the top and 5.0 at the bottom. Thanks to air pots my ph probe can go into the soil anywhere and any depth.

 

[fanleaf]

instead of spending all that money on this, just mix up some epsom salts 1 tbs / gallon and spray that on there. If it is magnesium you will see a pretty rapid deepening of the green, but nothing you can do now will bring the damaged areas back... they are gone.

Don't discount overwatering either. You can easily overwater by watering too often, it has very little to do with how much you give them each time. After seeing your entire plant though, and seeing equal damage all over the plant, I am even more convinced that this is a non-mobile nutrient problem, probably due to pH. This eliminates nitrogen, potassium and phosphorus, and phosphorus is not even in the picture really at this point in its life... that isn't till later in flower.

I am convinced that this is a trace mineral problem, most likely magnesium, most likely because your pH is too high. Figure out a way to get every liquid you give this plant to be at around 6.5 pH and I believe your problem will stop progressing. Also keep in mind that spraying something on the plant is a band-aid... it is not a permanent solution to this problem.

Don't Magnesium uptake easy at a 7.0 ph? If it is a Mag issue he could foliar feed her some epsom to get it in her more quickly.

 

[Emilya Green]

we are not even sure that you are at 7.0. My tap water runs at 7.8 here and yours could be anywhere. Also, we are not sure it is magnesium, all we are sure of is that it is one of the non-mobile nutrients, and most of them are trace minerals who's pH response is at the low end of the scale. The epsom salts should tell you real fast if it is magnesium or calcium... I am not convinced yet that this will be it.

 

[fanleaf]

we are not even sure that you are at 7.0. My tap water runs at 7.8 here and yours could be anywhere. Also, we are not sure it is magnesium, all we are sure of is that it is one of the non-mobile nutrients, and most of them are trace minerals who's pH response is at the low end of the scale. The epsom salts should tell you real fast if it is magnesium or calcium... I am not convinced yet that this will be it.

It wont be it! And Epsom will not tell you if it's magnesium or calcium. It will only tell you if it's Magnesium. That's all epsom is.

 

[fanleaf]

Flush with 15 gallons of distilled water if you don't know the ph and content of your source water and add new nutes.

 

[Emilya Green]

flushing is always a good bandaid, as is transplanting to new soil. It is best however, to figure out the problem that led you here.

 

[fanleaf]

flushing is always a good bandaid, as is transplanting to new soil. It is best however, to figure out the problem that led you here.

If a bandaid gets rid of what's killing the plant quickly than I love Bandaids!
He don't have a whole lotta time to play around trying one thing after another. This is not just a spot or 2 on the plant that he has time to figure out.

Flushing is NOT a bandaid. Flushing a plant from time to time using synthetic nutes and a few other reasons is a must at certain points. If he has a ph issue in the soil a flush is the only way to clear it out. I agree that when these things started showing on the plant that I would track down the problem but that's going to be hard when he has no reliable ph testing equip to start with.

Flush with distilled or RO water and add new nutes before it's too late.

This is not overwatering and the typical response of "add some calmag" won't fix this. There are deeper problems here than that.

 

[Emilya Green]

I am growing organically and could not flush my soil of nutrients if I tried. In my case, I would have no choice but to fix the problem... and would have been looking at it since the first yellowed cotyledon. Flushing all day long without fixing the underlying pH problem is not going to fix this... sorry, but this is does not appear to be a salt buildup or an over nute situation that would be fixed with a flush, without at least getting the last of that flush into the proper pH range. I guess we will have to agree to disagree on this, and let the OP experiment and figure out what is going to work.

 

[fanleaf]

I am growing organically and could not flush my soil of nutrients if I tried. In my case, I would have no choice but to fix the problem... and would have been looking at it since the first yellowed cotyledon. Flushing all day long without fixing the underlying pH problem is not going to fix this... sorry, but this is does not appear to be a salt buildup or an over nute situation that would be fixed with a flush, without at least getting the last of that flush into the proper pH range. I guess we will have to agree to disagree on this, and let the OP experiment and figure out what is going to work.

That's ok, we can disagree. That's why I told him to flush with distilled or RO water so we know it brings the ph into range. Too high or too low that will surely help!

 

[Emilya Green]

That's ok, we can disagree. That's why I told him to flush with distilled or RO water so we know it brings the ph into range. Too high or too low that will surely help!

Sorry to disagree again, but at the 7.0 pH of pure water, the pH is most definitely NOT in range for all of the trace minerals. It is ok at that reading for magnesium and molybdenum, but not most of the others.

we also have not considered what happens to his pH when adding nutes... usually it plummets to the 5's or even the 4's when you start adding nutes. This is indeed a mystery, but one that needs to be solved, and the OP does not need to be told to just throw pure water at it and call it good... I fear that we may be oversimplifying the problem, trying to find a fast solution.

 

[fanleaf]

Sorry to disagree again, but at the 7.0 pH of pure water, the pH is most definitely NOT in range for all of the trace minerals. It is ok at that reading for magnesium and molybdenum, but not most of the others.

we also have not considered what happens to his pH when adding nutes... usually it plummets to the 5's or even the 4's when you start adding nutes. This is indeed a mystery, but one that needs to be solved, and the OP does not need to be told to just throw pure water at it and call it good... I fear that we may be oversimplifying the problem, trying to find a fast solution.

Actually 7 is not that bad. It's surely better than wherever it is right now. If it's in the 5's it will bring him up closer. If it's at 8.0 it will help bring it down a notch. I can tell you I would much rather be at 7 than wherever that plant is at right now!

When he can get an accurate means to test ph then we can get more specific.

 

[fanleaf]

I am growing organically and could not flush my soil of nutrients if I tried. In my case, I would have no choice but to fix the problem... and would have been looking at it since the first yellowed cotyledon. Flushing all day long without fixing the underlying pH problem is not going to fix this... sorry, but this is does not appear to be a salt buildup or an over nute situation that would be fixed with a flush, without at least getting the last of that flush into the proper pH range. I guess we will have to agree to disagree on this, and let the OP experiment and figure out what is going to work.

I see you are a HAM. Me too!