Can you confirm this as Phosphorous deficiency?

As the title states, I would just like to confirm what I believe is a phosphorous deficiency before I proceed.
Strain is Nirvana's Master Kush. About 4 weeks old. I'm ruling out ph problems as its sisters (hopefully) receive the very same nutrient solution. Am I correct in assuming this? First pic was from last night, the second is from today. Same leaf.
Can someone help me out?

I believe this is a toxicity! Deficiencies usually progress allot more gradually. It may look like deficiency only because the high concentration of fertilizers mess up the pH.

JohnySmith1 said:

I believe this is a toxicity! Deficiencies usually progress allot more gradually. It may look like deficiency only because the high concentration of fertilizers mess up the pH.

Click to expand...

Well, ppm is only about 450, and it's the biggest plant of the three seedlings, yet the only one with issues. A lighter green than the others as well. What type of deficiency are you thinking?

I think it's fungus.

It's probably rust fungus.

Does look like a P def

You haven't splashed any water/feed on leaves n left under light..?

That progressed too fast for it to be P deficiency and if you google "Phosphorus deficiency cannabis" it looks nothing like P def.

How old is the plant. Can we get a full picture? I'd bet money it's a PH issue and those marks are Mg deficiency caused by nutrient lockout. Brown rust color in between the veins is a sure sign of it. It looks like it progressed fast but it didnt. You can see the same marks on both leaves but the 2nd picture is after the damaged plant cells died. Test your runoff and get that PH to a acceptable level. You can do a foliar spray with epsom salts to help the leaves out in the mean time.

Canninoobis said:

How old is the plant. Can we get a full picture? I'd bet money it's a PH issue and those marks are Mg deficiency caused by nutrient lockout. Brown rust color in between the veins is a sure sign of it. It looks like it progressed fast but it didnt. You can see the same marks on both leaves but the 2nd picture is after the damaged plant cells died. Test your runoff and get that PH to a acceptable level. You can do a foliar spray with epsom salts to help the leaves out in the mean time.

Click to expand...

Overnight, though?

P lockout is my bet.


Sent from my iPhone using Tapatalk

I have been giving it half strength nutes, including calmag. Should I up the calmag to full strength? I'm fairly confident ph is there, I use the same nute solution on other plants, but I'll check when I get home.

Calikron said:

I have been giving it half strength nutes, including calmag. Should I up the calmag to full strength? I'm fairly confident ph is there, I use the same nute solution on other plants, but I'll check when I get home.

Click to expand...

Don't be confident, be sure. It's highly important that you figure out your pH to determine whether or not it is actually lockout, which sounds more likely.

The only reason I'm saying confident instead of positive is because you bring it up as the most likely cause. I check the solution with a meter and confirm it with a liquid test. I have been wrong before though so I will double check when I get home, just weird that it's the only plant showing anything wrong.

Every answer here is wrong until you know exactly what was fed, how much and how often.What are you growing in? Dirt? Coco? What brand and how much of what and how often do you feed them? Until this information is given its all just a guess. But Calcium deficiency is one thing that you do have by your pictures. This may be the weaker of the plants showing less tolerance to being deficient. The others may ,or may not show symptoms

Like J Sparkle said - need info
Ph Grow medium, feed rate and nutrient type / make, ect....
If I guessed with no data known - NUTRIENT BURN

Take 25 ml of your soil put it in 100 ml of water (Reverse osmosis works best) check the TDS right away record this number. wait 8 hours recheck TDS (from same sample) The TDS should go up by no more than 200ppm.
example start reading 350 ppm
second reading 550 ppm

If your second reading is above 800-900ppm you are getting too high. back off your feeding and flush with ph adjusted water.

google; Plant Abuse Chart and Photos « Kind Green Buds
Good guide for quick reference....

The symptoms your example is demonstrating is called, interveinal chlorosis.

100% perlite hempy, feeding with Maxi series by GH, GH calmag, and Botanicare silica blast at half the recommended dosage, with Hydroguard at full recommended dosage. TDS at about 450 ppm, I think on that particular plant, the runoff comes out about 50 points higher. Fed every other day. Should I give full doses of calmag if ph turns out ok? This is first experience with seedlings, I usually work with clones

More pics.

Turns out the water sitting in the reservoir was pretty high, close to 7, and even when adding water at 5.8, the runoff came out at around 6.3. I always monitored runoff TDS, never really ph. Lesson learned.

This plant overall is noticeably lighter green then the other two seedlings (though the newer growth looks slightly better), and even more so than the clones of bubba kush. Hopefully this was the issue and she will recover.

I appreciate everybody's responses.

New growth looks un-affected by what ever it was.. good luck and happy growing,
Gaz