P deficiency?

I'm in coco, input solution pH is in check. Two plants showing symptoms, other two not and they're the same age. EC 1.6 with 0.2 tap/RO water, so actually 1.4 fed. Last week I added 0.3ml/L PK (standard product with 13/14 PK), but from then this happened.






I am thinking about P deficiency, I doubt it's light/heat burn, because temp and RH is in range, and light is at proper level (not newbie anymore).

So, what do you think?

Maybe adding that PK wasn't such a good idea. How can it be deficient in P if you gave some? I'm thinking maybe it was too much and now these are poisoned with it.

As noted above by Polishpollack, what's the logic on being short on P when you added additional P and now you have these issues? I would say you over did it. Lucky for you, you're growing in coco, which means you can basically reset your medium and move forward; that's what I would do.

It's strange that this would be toxicity, if we look into those pale green leaves with brown patches. Also this is my standard feed at this stage of growth and never have those problems, usually I drive smooth till the end of their life.

Why are you doubting light? What kind of light and how far away?

hotrodharley said:

Why are you doubting light? What kind of light and how far away?

Click to expand...

DIY Samsung strips, underpowered, and a lot from canopy. I am 200% sure this is not problem.

They look crispy to me.

KonopCh said:

I'm in coco, input solution pH is in check. Two plants showing symptoms, other two not and they're the same age. EC 1.6 with 0.2 tap/RO water, so actually 1.4 fed. Last week I added 0.3ml/L PK (standard product with 13/14 PK), but from then this happened.






I am thinking about P deficiency, I doubt it's light/heat burn, because temp and RH is in range, and light is at proper level (not newbie anymore).

So, what do you think?

Click to expand...

sorry I can't help, but I would like to know where u got the Scrog screen from?

What is your ph at? Its possible its too low so P could be locked out.

Whatever is going on here, it looks like a lockout of some kind. I see a phosphorus, potassium and possibly defecient or over nuted nitrogen. In regards to your curling upper leaves; could be humidity, light stress, maybe to much heat at the top of the canopy, or lastly low night temperatures. I'm not an expert grower but I have seen all this in the past many times.

Many times a grower will use the word "deficient" to describe a bad color of the plant. Plant leaves become something other than medium green in response to a variety of things. They could be nutrient or other environmental things. You have to look more at what was done in the grow process. Those leaves look like they're in a room that is too warm, but I don't know if that's the case. We can only go on what OPs write. It would be nice if they would write everything, yet make the text as concise as possible so we don't burn time reading a book.

If something is happening to two out of four then it's not going to be environmental, right? If we had the same symptoms across all four then environmental or nutrient would be obvious. Maybe you have root issues with the two that are having trouble.

Are they the same exact strain?

How often are you feeding?

Do your buckets drain?