Yellow/brown spots leading to yellowed leaves & curling up.

[JamesFarmer]

Hey All,

I am 3 weeks into flower with Blue Widow growing in RDWC. I have been running Lucas in the past and kept getting spots like you see below. I have tried a number of changes on successive crops and thought that I finally had it worked out. Everything was looking perfect until a few days ago and the spots are showing up.

Setup:

12/12 under HPS

RDWC running Snype's nute regimen. Similar to Lucas but with a 1:1.5 ratio instead of 1:2 and adding KoolBloom 1.25gm/gal at day 14 flower.

PH 5.8-6.1

TDS 700 (.5 scale)

My PH sat solid at 6.0 for quite some time.

Air temps: 68-75F

RH: 50-65%

The affected leaves were just upper fan leaves to start with. Now I am seeing some sign of the same on the very lowest fan leaves.

The symptoms look to me like either Phosphorus or Calcium deficiency. In the past I have added CalMag when I started seeing these spots. No change with the CalMag. That led me to believe that it may be a Phosphorous deficiency. With the switch in nute regimen I though I had it resolved. The addition of KoolBloom hits the K & P pretty hard. Unfortunately I am seeing spots again......

Take a look at the pics and let me know what you think? Is it Phophorous? Calcium? Could I be locking Calcium out at PH 6.0-6.1??

What do you all think?

 

[JamesFarmer]

Anyone?

 

[Green81]

Looks like a lock out, shouldn't you be running ph 5.6 another train of thought is to let the ph drift from 5.5 to 6 Over a 4-5 day period.
Maybe also trying to reduce your nutes down to 600-700 ppm(500) for the entirety of the grow. But it also depends on how hungry your girls can be some strains require less nutrients than other strains of Mary j.

Peace

G81

 

[Green81]

Temperature of your nutrient reservoir is critical to the uptake of nutes and availability of nutrients. Possibly?

G81

 

[DrDee]

Hi JF,
I've never done a DWC but have a few years hydro under my belt. Two things lead me to think you have a Mg deficiency. There might be other things going on too. First, your leaf shots show interveinal chlorisis (classic for Mg deficiency)...and secondly your genetics is 1/2 White Widow, a very Mg hungry strain.

You didn't mention your water source. If you're using RO water, then you should be adding 200 ppm Calmag always. And also, if that's the case, you probably are Ca deficient as well.
DrDee

 

[JamesFarmer]

Looks like a lock out, shouldn't you be running ph 5.6 another train of thought is to let the ph drift from 5.5 to 6 Over a 4-5 day period.
Maybe also trying to reduce your nutes down to 600-700 ppm(500) for the entirety of the grow. But it also depends on how hungry your girls can be some strains require less nutrients than other strains of Mary j.

Peace

G81

Thanks for the input. I am always hungry to learn more.

My best understanding so far is that the ideal PH in hydro is 5.8-6.0. I have been following Snype's threads and he is recommending holding 6.0.

Is this too high? It appears to me to be a compromise. Mg begins to lock out below 5.8 and K & P begin to lock out at 6.0. I would think that 5.8-6.0 swing would be the sweet spot?

What do you think??

Thanks again.

FJ.

 

[JamesFarmer]

Hi JF,
I've never done a DWC but have a few years hydro under my belt. Two things lead me to think you have a Mg deficiency. There might be other things going on too. First, your leaf shots show interveinal chlorisis (classic for Mg deficiency)...and secondly your genetics is 1/2 White Widow, a very Mg hungry strain.

You didn't mention your water source. If you're using RO water, then you should be adding 200 ppm Calmag always. And also, if that's the case, you probably are Ca deficient as well.
DrDee

Thank you for responding.

I am running RO and have not added CalMag. I have seen a similar issue in past runs with this strain and tried adding CalMag to address it. It didn't resolve the issue. But.... I had PH issues on that run also.

This run has been catastrophe free so far I was a bit surprised when this showed up on this run. Maybe it is Ca & Mg and the PH issue I had on the earlier run kept me from seeing proper results from adding the CalMag.

Does this make sense?

Thanks again.

FJ.

 

[JamesFarmer]

Temperature of your nutrient reservoir is critical to the uptake of nutes and availability of nutrients. Possibly?

G81

I have been running a chiller on past runs and kept the solution temp 65-67F. I saw similar issues with this strain while running the chiller.

This run I do not have the chiller online. My solution temps are running 69-75F. Roots are looking good. No signs of pythium or other issues.

This problem does not appear until around late week 2 to early week 3 of flower. I understand that the metabolic changes that take place during the first three weeks after the switch to 12/12 cause a change in nutrient requirements. That is what has me thinking it could be a deficiency or lockout.

Thoughts?

Thank you!!

FJ.

 

[DrDee]

James,
It's always best (and easier) to prevent rather then treat after a deficiency has occurred. So unless you're positive your nutrients have enough Mg...you should supplement. Many nutrient brands are aimed at a tap water of approximately 200 to 250 ppm. So if you're not getting the Ca and Mg from tap water (as with RO water) then you need to supplement.

On your last grow, if ph was too high, it could have been locking out Mg.
JD

 

[JamesFarmer]

James,
It's always best (and easier) to prevent rather then treat after a deficiency has occurred. So unless you're positive your nutrients have enough Mg...you should supplement. Many nutrient brands are aimed at a tap water of approximately 200 to 250 ppm. So if you're not getting the Ca and Mg from tap water (as with RO water) then you need to supplement.

On your last grow, if ph was too high, it could have been locking out Mg.
JD

I agree.

The nute regimen is "supposed to have enough" Ca&Mg so I have not been adding more. I do see that others using this regimen all appear to be running tap water where I am running RO.

I started CalMag last night.

 

[DrDee]

James,
The companies don't always give you enough info to make such decisions. But if a company offers a "hard water micro" then you can assume that their regular micro has enough Ca and Mg.

But if they don't offer it, then it's reasonably safe to assume the nutrients are designed for tap water...so that means supplement.

Some guys are knowledgeable enough to evaluate each individual nutrient level in a nute solution...but that's not me.

Hope the CalMag helps...
DrDee

 

[JamesFarmer]

James,
The companies don't always give you enough info to make such decisions. But if a company offers a "hard water micro" then you can assume that their regular micro has enough Ca and Mg.

But if they don't offer it, then it's reasonably safe to assume the nutrients are designed for tap water...so that means supplement.

Some guys are knowledgeable enough to evaluate each individual nutrient level in a nute solution...but that's not me.

Hope the CalMag helps...
DrDee

I hope it works as well. I have had good results with this strain in RDWC in spite of the issue. I just want to learn to do better

Thank you very much for giving a hand.

FJ

 

[DrDee]

JF,
No problem...happy to help. Just curious, on your previous grows of the Blue Widow, did you get any of the lightening between veins like in picture 2 above?

Oh, and I had another look at the pictures and #3 looks more like a ph fluctuation issue. So it could be that your ph variations blocked Mg absorption. You still need the Mg supplementation and may for the duration, but just keep a closer eye on ph to make sure everything can be absorbed and used.
Peace,
DrDee

 

[Ras Mason]

ample aeration? sometimes low oxygen will create a problem with magnesium and nitrogen...
powdered kabloom is around week 6 and 7, never before on a ten weeker.....
just saying...

Excessive wind in the area?
colder than a mofcker down here.

 

[yerboyblue]

I am here to second the pH fluctuation method. I try to keep it 5.8-6.0 for the most time, but I let it get down to 5.5/5.6 and back up to 6.2/6.3 for a couple days on each end before readjusting. Also the lower end of the pH spectrum is more ideal for flower, at least what I have noticed. I am on my 3rd run in rDWC, basically an undercurrent system, and have noticed a great response to lower ppm, like 400-500.

Also, Ras asked about aeration, which could contribute, especially if you are running water warmer at 69-75. My last comment is about the environment, I had some similar damage due to offgassing, that would start as a combo of mg and ca deficiency week 2 or so of flower, then just progress from there. It had to do with the paint I used in the room, but other things like flexible (not standard) PVC hosing can do it as well.

 

[JamesFarmer]

JF,
No problem...happy to help. Just curious, on your previous grows of the Blue Widow, did you get any of the lightening between veins like in picture 2 above?

Oh, and I had another look at the pictures and #3 looks more like a ph fluctuation issue. So it could be that your ph variations blocked Mg absorption. You still need the Mg supplementation and may for the duration, but just keep a closer eye on ph to make sure everything can be absorbed and used.
Peace,
DrDee

The "yellowing" is actually many yellow spots. And, Yes my earlier grows had a similar issue.


As to PH, it has been very stable & manageable. I did hold it at 6.0 for some time and have since eased it down to 5.8 and am allowing a bit more "swing".

 

[JamesFarmer]

ample aeration? sometimes low oxygen will create a problem with magnesium and nitrogen...
powdered kabloom is around week 6 and 7, never before on a ten weeker.....
just saying...

Excessive wind in the area?
colder than a mofcker down here.

Plenty of air. 110lpm air pump running 8 airstones supporting 4 plants.

I battled with that early on. Plants looked overwatered and puny.

Wind? Yes...
Cold? Got up to 33F today.... Mostly been in the 20's...

 

[DrDee]

James,
OK, sounds like you're on top of things. The addition of the CalMag should make a difference...though give it a bit of time.
Peace,
DrDee

 

[JamesFarmer]

I am here to second the pH fluctuation method. I try to keep it 5.8-6.0 for the most time, but I let it get down to 5.5/5.6 and back up to 6.2/6.3 for a couple days on each end before readjusting. Also the lower end of the pH spectrum is more ideal for flower, at least what I have noticed. I am on my 3rd run in rDWC, basically an undercurrent system, and have noticed a great response to lower ppm, like 400-500.

Also, Ras asked about aeration, which could contribute, especially if you are running water warmer at 69-75. My last comment is about the environment, I had some similar damage due to offgassing, that would start as a combo of mg and ca deficiency week 2 or so of flower, then just progress from there. It had to do with the paint I used in the room, but other things like flexible (not standard) PVC hosing can do it as well.

Interesting.... The symptoms you describe sound strikingly similar. 2+ weeks into flower and the spots start showing.

I sheathed the flower area with OSB, sealed with Great Stuff foam, painted with Kilz primer and lined the walls with mylar bubble wrap.

I have never heard of anyone having issue with off-gassing associated with these common products. Also, the space was finished about a year ago.

Things that make you go Hmmmm..

 

[Ras Mason]

i meant if a fan was blowing harder on thos areas....
if not ...test your runoff frm an affected plant...
if not....might be the mighty HRM....

BOOOOHHH!!!!!