Moisture stress from nute burn.

Looking for a little bit of confirmation on my theory for what is wrong with this plant. All the conditions are within range, but this sticks out as what I believe to be the cause.

"When you have a high concentration of salts in solution (or in the root medium) compared to lower salinity levels found in the plant’s tissue, water is actually drawn out of the plant across the root gradient in order to fix the ppm imbalance."

What I do know from observation:
Old growth
Starts at bottom of plant
Fan leaves
Damage begins at leaf points and progresses to browning between the veins
Brown necrotic spots continue to spread between the veins with dry leaf curling occuring at the ends.

Two of their siblings (regular MF seeds) got culled for herming, and this is the lone survivor. It's survived a several day darkness problem, as well as one prolonged drought (6 days versus normal 3 days for watering) when I was out of town. The veg period was very short as I'm working with a narrow harvest window before moving. It sprouted 2/23 and flower started 3/24.

Here is the recent feeding history. Nutrients are DG FP, PT, and Bloom.

3/30 F7
GAL WATER
6.6 PH
540-180= 360 PPM
1/2 tsp PT per gallon
1/4 tsp FP per gallon
1 tsp B per gallon

4/4 F12
2.5 gal water
Good runoff
6.5 PH water
Culled one male plant

4/8 F16
3 gal
870-180= 690 PPM
6.4 PH
1 tsp PT per gallon
1/2 tsp FP per gallon
2 tsp B per gallon
Lots of runoff

4/14 F22
2 gal
3/4 tsp FP PER GALLON
2 TSP B PER GALLON
One plant remaining due to suspected herm.
Tons of RO
900-180= 720 net PPM
PH balanced to 6.1 with no PT

4/17
1.5 gal water
6.5 PH
Good RO

At this point I'm thinking maybe run some zyme to try to clean up the root zone first. The PPM doesn't seem very high considering where it is in flower. I will say that my shit water comes out to 7.8 from tap so even with PHing the water, I'm almost positive the medium PH drifts upward over time regardless. I've read some articles from the makers of Promix BX which I'm using and they mention the PH drift being an issue over the life of the grow. I suppose I could run distilled water for awhile and add nutrients. The plant is drawing nutrients from the leaves; the question is why? Any ideas here? I think I'm on the right track, but I'm always willing to hear alternate ideas that maybe I'm missing.

What do PT, FP, and B stand for? Since you’re using R/O water are you adding micronutrients? R/O water has no Ca, or Mg (or anything else).

When I've had issues like you're having it's been because I'm letting the plant dry out too much. I was told it leads to spikes in ppm at the leaf tips causing burn. Not sure if that's 100% accurate but watering smaller amounts daily seems to have fixed it. I'm in Roots Organic original and it drains pretty fast. I deal with oh drift as well as I use Citric acid for ph down on my well water and it doesn't hold oh for long. I compensate by watering at around 6.3 and letting it drift upwards.

FirstCavApache64 said:

When I've had issues like you're having it's been because I'm letting the plant dry out too much. I was told it leads to spikes in ppm at the leaf tips causing burn. Not sure if that's 100% accurate but watering smaller amounts daily seems to have fixed it. I'm in Roots Organic original and it drains pretty fast. I deal with oh drift as well as I use Citric acid for ph down on my well water and it doesn't hold oh for long. I compensate by watering at around 6.3 and letting it drift upwards.

Click to expand...

If you see I made a post earlier had a white truffle had some fans look similar to this.. I just switched over to led am getting used to them loved them for flower but veg is a bit to get used to. I believe mine was just a bit of nute burn from a overferting the white truffle cut is prone to it I guess. I'm backing down on my ec. I'm in promix hp 5 gal fabric pots, r/o water, and co2.

Been ph'n at 6.0 in veg and haven't gone past 800ppm yet

Phytoplankton said:

What do PT, FP, and B stand for? Since you’re using R/O water are you adding micronutrients? R/O water has no Ca, or Mg (or anything else).

Click to expand...

Sorry I assume too much with the myriad acronyms we have here. PT is silica, FP is foliage pro (complete veg), and B bloom (complete bloom). Also confusing enough for me RO is runoff, not Reverse Osmosis. My tap is crap at like 7.8 PH.

FirstCavApache64 said:

When I've had issues like you're having it's been because I'm letting the plant dry out too much. I was told it leads to spikes in ppm at the leaf tips causing burn. Not sure if that's 100% accurate but watering smaller amounts daily seems to have fixed it. I'm in Roots Organic original and it drains pretty fast. I deal with oh drift as well as I use Citric acid for ph down on my well water and it doesn't hold oh for long. I compensate by watering at around 6.3 and letting it drift upwards.

Click to expand...

I've been doing research and I've been wondering how hard it is to even overwater Promix. It seems a lot like coco where the drainage is so good it shouldn't be an issue. I go by pot weight, but maybe the pot being light is too much? I will say the new shoots from stretch all look very fresh and green, so some of what we're seeing may be worsening of the original condition as I haven't defoliated any of the bad leaves. I do know if the medium dries too quick then the osmosis definitely pulls moisture from the plant tissue. I will say I don't think I've seen this plant fat and droopy from overwatering a single time which again leads me to believe there may not be overwatering with Promix, especially with fabric pots. I also can't downplay that one severe drought spell of around 5 days or so while I was gone. Some roots had actually started to grow through the top of the medium and from the exposed stem itself trying to find moisture. I'll be curious to test out the Zyme a bit to see if that helps clean up the root zone. Still can't find an answer if Zyme has an acidic or alkaline effect. The silica is so alkaline I've actually cut back and now only use it to buffer against the acidic base nutrients. With my shitty tap water, I worry about overall PH drift throughout the grow.

What is EC of your water? Do you have a quality report on what's in it? Personally if it was my plant I would think potassium lockout or deficiency

MannyPacs said:

What is EC of your water? Do you have a quality report on what's in it? Personally if it was my plant I would think potassium lockout or deficiency

Click to expand...

Water tap PPM is 180 and around 7.8PH. It causes lots of scaling on fixtures due to lots of limestone in the ground.

Here are some updated pics of the plant and some of the leaves. The new growth still looks good and the buds appear to be growing well. Whatever it was seems to be mostly resolved. I've seen this on several of my grows however so it would be nice to find out definitively what it causing the intravenous damage.

Here's an updated couple of pics. Still not quite sure what it is, but it appears to only be mildly impacting the plant as the plant is coming along quite nicely. I'm still guessing some sort of moisture stress/burn, but I added in some Zyme into today's feeding to see if maybe it's a root zone issue.

As someone whose preferred medium is promix hp I'm going to just offer this one bit of advice.. start using RO water and a simple 1 or 3 part nutrient system. As long as your light, Temps and rH are dialed in this will save you a ton of headaches. If you can't afford to install and RO system in your house check out your local grocery store. At mine I can get 5 gallon refills of RO for dollar. I have 6 5 gallon jugs I fill up as needed. It just makes everything easier. Less issues with nutrients falling out of solution, more stable pH, less math. Once I committed to using RO and a simple nutrient program growing in promix is literally easy mode.