Simultaneous signs of Burn & Deficiency?

[olegren]

Hi, friendly infirmary folks! I am back again. I decided to make a new thread since this issue seems distinct from previous problems we've talked about. I sincerely appreciate any wisdom you can share about the best steps I might take to get them back on track.

Problem: I'm seeing burnt tips on newer growth with most of my plants, but those same plants are also showing yellowing/fading of lower growth that suggests a nitrogen deficiency. I'm also seeing pronounced interveinal chlorosis on new growth for all four plants. Older growth has scattered but increasingly prominent splotches of rust, yellows, and browns. Color across the board looks a bit pale (like lime green) to me.

The symptoms are similar enough that it must be something I'm doing, but I can't figure out which way to go in terms of adjustments.

Medium/grow method: Soil. HF + Perilite (75%/25%) Accurate 8 says soil is 7.0 when dry; and 6.2-6.8 when I push the probe deeper while there's still moisture from a feeding present. I've been letting moisture levels get to 1-2 between waterings.

Feed: and supplements used: Prescription Blend + CalMag. Originally I was feeding full dose once per week and then doing a plain RO watering in between. I have more recently shifted to half dose of Rx Blend + Half Dose of CalMag. I gave them their first feeding like this on Friday (Week 1 flower nutes half dose) and intend to keep feeding steadily at this rate for a full dose of nutes per week but at a steady rate.

water source: RO Water (~12ppm from stealth RO system)

Strain/age: Bruce Banner Auto (Southern Oregon Seeds) & Forum Stomper x CDLC (Mephisto). All are 43 days old today. All problems seemed to appear/intensify as we got to flower.

light used: HLG 260W QB V1. Everyone's getting ~40K lux right now; around 600 ppfd per vendor specs. On 20/Off 4. I have gone up about 8K lux in the last 5 days at 1-2k/day.

Climate: Daily average is 79.3F & 53.5%. Temps maxing out at about 82F and RH dips as low as about 45% lately. Dark is more like 72F/65% RH.

Additional info: I'm using my Accurate 8 to check soil PH and make sure that's not my problem. The closer the soil is to dry, the more likely it is to come up at 7.0 or right at that. However, when soil is moist, I'm getting readings between 6.2 and 6.8 deep down in the root zone.

The top left specimen has been ahead of the others for the last several weeks. She was the first to show the pale/yellowing towards the older growth, so I immediately gave more nutes. This seems to have kept the yellowing from progressing higher, but I'm confused by the burnt tips. Her color is still ideal up top, but I am concerned I'm running out of margin for error with her as flower sets in.

 

[Arthur]

RO always needs to have something added to it. Seems it will find a ppm medium. Even if that's by robbing it from your soil.
The girls look hungry to me

 

[Proph]

Soil ph is rarely an issue. It's buffered to stay within range. You need to check the ppms of your feeds, as well as the ppms of the run off like once a week.. I am not a fan of adding "calmag" at all.. It seems to cause more problems than it could ever fix if not understood correctly. Calcium is found in almost everything. Too much calcium will lock out magnesium and a few other nutrients. Too much magnesium will lock out calcium and a few other nutrients. So deficiencies do not automatically mean "add more".. They are often the first sign of a lock out. The ppms confirm whether or not there is an excess of nutrients in the soil. It will also confirm if there is not enough. Ppm info also tells you how much you plant is feeding, or if its not feeding at all.. Some plants do look underfed.. Which could be due to a lock out.. But without ppm info, it's all guess work. You should be testing the ppms of your feeds before you use them, as well the run off. As the plant feeds, the ppms will lower, and the ph will rise. If your run ppm is higher than your starting feed ppm, there is an issue. I've never fed more than 700 ppms max (in mid flower) when growing autos.. 500ppms is usually my cut off for autos. Anything over that and it tends to cause issues. It's a lot easier to add something if something is needed. It's much harder to remove something, if something is in excess.. Less is more kind of thing. Can you get a ppm of your feed next time you mix some up.. And a ppm reading of the run off (after a few cups full) after you feed?

 

[olegren]

Thanks, folks. This is great stuff! I really appreciate the sanity check.

@Proph - I had been checking PPM of my feeds but never once took PPM of runoff. That is a great idea, and I will do this. Also, unfortunately for some reason I did not document my PPM of the last feed - which was the first time I gave the calmag. The feed before that was at 410 ppm ,and all its predecessors were there or below. (I was going by the Rx Blends guidelines on their feeding schedule)

The last feeding should've been pretty similar, but it did have that calmag half dose in there on top of the half dose of flower nutes; so probably a bit higher. Also, I can appreciate what you're saying about calmag and I believe Waira also mentioned that they never needed to use additional calmag on top of the Rx Blend nutes.

It sounds like my best course of action would be to record PPM going in on the next feed (Probably tomorrow based on moisture levels) - and then take runoff to validate that it is indeed lower and not higher.

Thanks again!

 

[Mañ'O'Green]

Your soil needs to be wet and the probe needs to be clean to get an accurate PH reading. Yours at 6.2 to 6.8 is good.

It looks like a classic Lock-out too much Cal-Mag. Do a nutrient Flush with PH 6.4 to 50% run-off then Fertigate with Re-charge and Big Bloom following label instructions to 15% run-off. Add Calcium back into the RO water at 50 PPMs before mixing the Big Bloom and recharge in.

 

[Mañ'O'Green]

I cannot find Rx-Blend (nutrients line) please be more specific about your use of this product name and line.

 

[Silver]

Soil ph is rarely an issue. It's buffered to stay within range. You need to check the ppms of your feeds, as well as the ppms of the run off like once a week.. I am not a fan of adding "calmag" at all.. It seems to cause more problems than it could ever fix if not understood correctly. Calcium is found in almost everything. Too much calcium will lock out magnesium and a few other nutrients. Too much magnesium will lock out calcium and a few other nutrients. So deficiencies do not automatically mean "add more".. They are often the first sign of a lock out. The ppms confirm whether or not there is an excess of nutrients in the soil. It will also confirm if there is not enough. Ppm info also tells you how much you plant is feeding, or if its not feeding at all.. Some plants do look underfed.. Which could be due to a lock out.. But without ppm info, it's all guess work. You should be testing the ppms of your feeds before you use them, as well the run off. As the plant feeds, the ppms will lower, and the ph will rise. If your run ppm is higher than your starting feed ppm, there is an issue. I've never fed more than 700 ppms max (in mid flower) when growing autos.. 500ppms is usually my cut off for autos. Anything over that and it tends to cause issues. It's a lot easier to add something if something is needed. It's much harder to remove something, if something is in excess.. Less is more kind of thing. Can you get a ppm of your feed next time you mix some up.. And a ppm reading of the run off (after a few cups full) after you feed?

Fantastic information again @Proph ..what nutrient line was you using before you delved into organic?

 

[olegren]

I cannot find Rx-Blend (nutrients line) please be more specific about your use of this product name and line.

@Mañ'O'Green - Sure: It's Prescription Blend. Waira recommended them to me (I think they'd just onboarded as an af.net vendor) back in the Spring, so I've been giving them a go.

 

[Mañ'O'Green]

@Mañ'O'Green - Sure: It's Prescription Blend. Waira recommended them to me (I think they'd just onboarded as an af.net vendor) back in the Spring, so I've been giving them a go.

Are you using the whole line - what are you putting in the pot don't keep it a secret

 

[Mañ'O'Green]

HOLD the Presses you are running Happy Frog not Ocean Forest. HF needs a balanced fertilizer not just Big Bloom. Fox Farms recommends 4-9-3 how close is Prescription Blend to a 4-9-3?