Is this an Iron deficiency or something else?

[DaddyKush]

This is a Dark Star 2 weeks into flowering. It's in soil (pH is 7.0) under a 400w HPS. Was vegged under 400w LED. Using Remo nutes, full line. Only the new growth is affected and I believe it's an iron deficiency but was hoping for some fresh opinions before I take corrective action.

 

[Bud]

Hay have u been given her PH 7.0 consistently??? Best PH in soil is 6.5 by my meter.

 

[Mr. Krip]

Looks like a Magnesium deficiency (extreme!). You can tell from the "intravenal chlorosis" (yellowing between the leaf veins while the veins stay green). Are you using RO water? If so, you typically need to add Cal-Mag. While they look similar, you can tell it from an iron deficiency because iron will usually have white (not yellow) between the veins.

 

[MrSauga]

Looks like a Magnesium deficiency (extreme!).

I'm gonna jump in and support that call as I also see the tips twisting and curving upwards a bit. Another good sign.

 

[Weaselcracker]

In the past I’ve always called that an iron deficiency. Whether or not I’m correct about that - in any case it should be correctable with Calmag, which usually contains iron.(And of course making sure the ph is right, as alway)
Worked for me. The lovely thing about iron deficiency is that the symptoms are reversible.

 

[Mr. Krip]

In the past I’ve always called that an iron deficiency. Whether or not I’m correct about that - in any case it should be correctable with Calmag, which usually contains iron.(And of course making sure the ph is right, as alway)
Worked for me. The lovely thing about iron deficiency is that the symptoms are reversible.

Well, again, they look similar, but they are very different. Any nutrient that has iron (pretty much all of them!) will fix an iron deficiency. Most nutes, however, do not have the Cal-Mag (I guess they're counting on tap or well water to supply it!) and both calcium and magnesium get stripped out in the RO process, so when using RO it's ALWAYS good practice to add Cal-Mag.

 

[Mr. Krip]

BTW, assuming it is magnesium, a foliar with epsom salts will help quick!

 

[DaddyKush]

Thanks for the answers guys. So if I give some extra CalMag as a foliar spray, that should correct it?

 

[Mr. Krip]

Thanks for the answers guys. So if I give some extra CalMag as a foliar spray, that should correct it?

Yes! And, I'd add some to the nutrient/water solution when you feed/water

 

[Weaselcracker]

Thanks for the info Mr. Krip. I’m not an expert on this stuff by any means. I thought that magnesium deficiency would show up in the older growth not the new growth. All I know is that this type of problem is about the only deficiency I ever had with symptoms that actually go away when you fix the cause. In my case my pH was too high.

 

[Mr. Krip]

Thanks for the info Mr. Krip. I’m not an expert on this stuff by any means. I thought that magnesium deficiency would show up in the older growth not the new growth. All I know is that this type of problem is about the only deficiency I ever had with symptoms that actually go away when you fix the cause. In my case my pH was too high.

If it was PH it was almost certainly Magnesium. Magnesium gets "locked out" when PH is above 6.4 in soil. For iron to be locked out, PH has to be extremely low or so high that a lot of other issues would be evident.

This is a great reference (if you haven't seen it!):

Cannabis Plant and Pest Problem Solver - Pictorial

 

[DaddyKush]

I was giving extra CalMag during veg due to using LEDs but I lowered the dose when I switched to HPS for bloom. That's likely what caused the problem. My sincere thanks guys, I'll rest easy tonight.

 

[Weaselcracker]

If it was PH it was almost certainly Magnesium. Magnesium gets "locked out" when PH is above 6.4 in soil. For iron to be locked out, PH has to be extremely low or so high that a lot of other issues would be evident.

This is a great reference (if you haven't seen it!):

Cannabis Plant and Pest Problem Solver - Pictorial

Definitely looked through that problem solver many times in my younger days. I don’t try too hard to decipher deficiencies much anymore. I guess cause I suck at it. Not the only one around here though, I guess. So many interconnected factors. I find most are messy enough to be indecipherable and it’s easiest for me to just go straight to the source of the problem (me) and triple-check all the basics to eliminate the mistakes I’ve made in my environment- often ph.

Edit- now that I look at the OP’s pic again I see what you mean -and how it looks like that striped sort of Mg deficiency, and not the overall extreme pale yellowing I was thinking of.

But I’m still curious about what you said about iron deficiency.

So is this following info wrong?

“In soil, iron is best absorbed by the roots in the 6.0 – 6.5 pH range (although it’s generally recommended for soil growers to keep pH in the 6.0-7.0 range, iron tends to get locked out when the pH is higher, especially above 7.0)”
Looks like you don’t have to go very high to lock out the iron. (?)

The two or three times I’ve had this issue with that bleaching/albino appearance, after I dropped the ph the symptoms reversed and the leaves went green again.

That reversal is not something I remember happening with Mg deficiencies, I think.
It’s what made iron def (or what I assumed to be iron def) my favourite deficiency. A deficiency that goes away.

Not questioning your knowledge Mr K, just curious.

 

[Mr. Krip]

Definitely looked through that problem solver many times in my younger days. I don’t try too hard to decipher deficiencies much anymore. I guess cause I suck at it. Not the only one around here though, I guess. So many interconnected factors. I find most are messy enough to be indecipherable and it’s easiest for me to just go straight to the source of the problem (me) and triple-check all the basics to eliminate the mistakes I’ve made in my environment- often ph.

Edit- now that I look at the OP’s pic again I see what you mean -and how it looks like that striped sort of Mg deficiency, and not the overall extreme pale yellowing I was thinking of.

But I’m still curious about what you said about iron deficiency.

So is this following info wrong?

“In soil, iron is best absorbed by the roots in the 6.0 – 6.5 pH range (although it’s generally recommended for soil growers to keep pH in the 6.0-7.0 range, iron tends to get locked out when the pH is higher, especially above 7.0)”
Looks like you don’t have to go very high to lock out the iron. (?)

The two or three times I’ve had this issue with that bleaching/albino appearance, after I dropped the ph the symptoms reversed and the leaves went green again.

That reversal is not something I remember happening with Mg deficiencies, I think.
It’s what made iron def (or what I assumed to be iron def) my favourite deficiency. A deficiency that goes away.

Not questioning your knowledge Mr K, just curious.

No worries, Brother! It's perfectly OK to question my knowledge and I do it all the time myself!

Also, it's very possible you are correct since the two deficiencies look similar and we're both diagnosing from a single pic.

That being said, here's my reasoning...

This chart shows PH ranges for MMJ in soil (on right) and hydro (on left) and I'm sure you've seen this, or something similar:

With soil, once you start going above a ph of 7.0, not only iron but LOTS of stuff starts getting locked out. Because of this, iron deficiencies often accompany other deficiencies.

The main difference between the iron and mag deficiencies is that the iron will effect the top/newer growth and mag tends to effect older growth towards the lower/middle of the plant.

You're correct that, when the iron deficiency is corrected, the leaves can green up again.

Here's more info on iron deficiencies:

• Newest leaves are completely yellow when they first grow in
• The bright yellow (almost white looking) color on new growth is the signature sign of an iron deficiency.
• Sometimes the affected yellow leaves are so damaged they’re beyond recovery. Other times the yellow parts of the leaves may begin to turn green as the plant continues to grow, starting from the tips and moving in toward the base of each leaf
• Eventually an entire leaf can become green and relatively healthy looking, even though it started out completely yellow from an iron deficiency. The ability of yellow leaves to eventually turn green is another signature of an iron deficiency, because for most other nutrient deficiencies any yellow leaves can’t truly turn green again.

However, when using RO water, which is very common among growers, you can almost bet on a mag deficiency unless they're adding Cal-Mag.

The three nutrients that can cause problems, even with proper PH are nitrogen, calcium and magnesium. Even if the PH is ideal, these three nutrients needs to be supplied in high enough quantities to prevent deficiencies.

The other "tell-tale" sign of a mag deficiency is purple petioles & stems, but I didn't notice these were visible in the pic.

So, iron deficiency is a good, and possibly correct, guess. I'm going with the magnesium just because it would be much more likely.

While the Cal-Mag does have iron in it, I don't believe it's typically used to address iron deficiencies. It's because calcium, magnesium, and iron all have to be present in some appropriate ranges and lacking any one of these can cause deficiencies in others.

******************************
Wait!

I just went back and was looking at the pic again in the original post. I'm sorry! I must have missed the whole note at the bottom saying this was only occurring on the top growth and PH was 7.0!

OK...I'm switching to iron deficiency!

For an iron deficiency caused by PH, you typically don't need to add iron. You just need to flush and get the PH of the soil back down to around 6.5. Adding more iron won't help if PH is off.

VERY sorry for the confusion I caused on this one!

 

[Ganjagrowergu]

It seems like no matter what problem I have nowadays, it is always related to my current pH. When in soil I always ph'd at 6.5, now in Hempy I do 6.0. On the rare occasion that I test my runoff, sometimes it will be very high, I will pH closer to 5.5 for one feeding and resume 6.0 feedings the next day. I've never had iron def, but cal or mg was my biggest problem in coco/soil.

Morning rambling, sorry guys, you got the brunt of it..... Lol

 

[Weaselcracker]

Thanks Mr Krip! I’m so glad to meet someone who’s capable of getting a little confused sometimes and doesn’t mind admitting it. Me- I’m confused almost all of the time.

I did mid-speak a bit in my first post too when I implied that Calmag would necessarily fix it. The chain of events when I got that issue was - I went for the calmag bottle first, but as usual it was a PH issue in the end.



Ganja - In my experience PH is absolutely the main grow devil for anyone growing in any form of hydro, as you are.
I never go as high as 6 anymore. Anything above 5.8 freaks me out.
I ph at 5.6- 5.8.
PH seems to always climb in the root zone- at least in my grows. I can’t speak for all growing methods.
So runoff will be higher than what went in, and a nice PH range can be accessed by the plant if you start low. I think Iower is generally better.

I test ran a plant all the way through veg at a PH of 5.2 once, and a clone of it at 6.2. I ended up tossing the 6.2 plant out it was so sickly. The plant that was grown at 5.2 was twice as big and in perfect health.

That ‘aim low and let it sweep upwards naturally’ idea is my basic working theory these days and seems to be working well so far.

 

[Ganjagrowergu]

Thanks Mr Krip! I’m so glad to meet someone who’s capable of getting a little confused sometimes and doesn’t mind admitting it.




Ganja - In my experience PH is absolutely the main grow devil for anyone growing in any form of hydro, as you are.
I never go as high as 6 anymore. Anything above 5/8 freaks me out.
I ph at 5.6- 5.8.
PH seems to always climb in the root zone- at least in my grows. I can’t speak for all growing methods.
So runoff will be higher than what went in, and a nice PH range can be accessed by the plant if you start low. I think Iower is generally better.

I test ran a plant all the way through veg at a PH of 5.2 once, and a clone of it at 6.2. I ended up tossing the 6.2 plant out it was so sickly. The plant that was grown at 5.2 was twice as big and in perfect health.

That ‘aim low and let it sweep upwards naturally’ idea is my basic working theory these days and seems to be working well so far.

I don't really know why my grow is doing so well. I started with pH about 5.5 at the beginning of the grow and they just drooped and looked sickly. I flushed them out with ph 6.0 and decided to leave it there.

I do have a rising pH in my root zone as well. However I believe that my 2x daily feedings seem to keep it fairly stable. I haven't checked runoff for quite awhile. Them liking the pH at 6 may just be my genetics... My neighbor tried to tell me not to bother with checking pH. .

 

[Weaselcracker]

Yeah is right.
I’d say don’t bother checking runoff, except in rare cases. But checking ph is essential unless you’re in a soil grow.

 

[Ganjagrowergu]

I only check it when I am really really bored. I check my feed pH like 2x monthly, because I have been mixing it the same way everyday, but it is still good to be sure every now and then.

 

[Pyr0]

I've quickly learned, especially when growing in soil, that when my plants showed some sort of deficiency it was never because they wern't getting enough when being fed. It was nearly always caused by lockout due to Ph problems.

Constantly watering at 7.0 is not great for soil, I'd flush that with a good few gallons of water and start feeding it at a lower Ph for a while, even 6.8 will help. Personally I try to go for the Devil's number 6.66 seems to work for me ;-)

Peace