Urgent help for medical harvest - CBD Therapy

[cbdthc01010]

Hi all, this is my first thread and I hope to be posting in the right place.
It's also my frist indoor experience due to the need of medicine, but I'm going through some problems that may be damaging my harvest (which I really need, and I can't have other cylces during this year).

Everything was going well until last week, the 3rd of flowering when I noticed some yellow spots mainly on the upper fan leaves. Bottom leaves are greener than the top leaves and this makes me think it can't be a N deficiency.

The situation was alright until then; plants were a little bit full of N but there wasn't a single burnt spot on leaves. After I gave them 1L of water each with [ 3ml/L BioFlores + 3ml/L BioBoost + 0.5ml/L BioRhizotonic ] situation started to get bad.


I assume this is a nitrogen toxicity due to the fact of different green shades on leaves - but I'm not sure and don't know wether to flush or how to act.

Strain - 50/50 hybrid - CBD Therapy - CBD Crew
# of Plants - 2
Grow Type - Soil
Grow Stage - Flowering
Bucket Size - 11L
Lights - (1) 150 Watt HPS Agro
Nutrients - Organic BioCanna complete line
Medium - Atami Light Mix
PH - 6.8-7
RH - 40% min with lights on to 55% - 75% max with lights off
Room Temperature - min 15°C lights off and max 27 lights on
Solution Temperature - 20°C
Room Square Footage - 60x60x150 cm
Pests - None

Here are some pics tracking the evolution of the yellowing/browning:

And here's a flower; it seems to me that it's still growing discretely and having a good trichome production.

If any other info is needed I can provide it.
Hoping somebody can help me, it will be much appreciated, really.

 

[Dwight Monk]

Your pics not showing up, this thread walks you through how to upload and post pics here:

Photo Gallery Guide - How to Resize, Upload & Post Photos

 

[KingstonRabbi]

Can't see pictures, but doesn't sound like N toxicity. Here is link to problem solver guide, best one on web.

Cannabis Plant and Pest Problem Solver - Pictorial

 

[cbdthc01010]

Thank you both for answering me guys.

@UrbanMonk:
Thanks for letting me know, I could see them but they should be visible to everyone now.

@KingstonRabbi:
I checked that guide but still ain't sure if it's a N def/tox and since it's completely the opposite I wanted to be sure before proceeding.

Second pic was taken two days after the first, some leaves have been removed to avoid mold.
As you can see the lower part is still a nice darkeish green

And here's the flower I was talking about:

 

[KingstonRabbi]

That looks like N deficiency that happens in flower but not this early. Probably Magnesium and others also. Not familiar with nutes you are using but it looks like underfeeding.

I would increase feedings and do a foliar spray with weak nutrient solution. Also add 1 tablespoon of epsom salts to container. Worst leaves may not recover but plant will overall.

Hopefully someone with more experience will be along to give you more precise response.

 

[Weaselcracker]

It does look mostly like N deficiency to me as well. You said the colours were reversed ? but mostly I see old yellow growth and new greener growth. Also the yellowing pattern in the middle leaves looks a bit like magnesium deficiency but it could be just the N again I'm not sure. I think KR's advice is good. All your yellow leaves are going to stay yellow but unless it spreads a lot more then your buds will still be fine.
Without knowing anything about your nutrients, make sure there is a source of N in the flowering mix. My flowering nutes work out to roughly 10-20% N (varies depending on the stage). They do need some. Don't make any drastic changes though- just smallish ones (like 20% more/less feeding rates at the extreme max) - or you'll probably regret it.

 

[cbdthc01010]

Yeah I meant to say that the leaves weren't yellowing from the bottom to the top like I've read in many guides but you're right.

Ok so I've given them some water with a low amount of BioVega (1ml/L) and sprayed some leaves with the same solution. I haven't got any epsom salts now but I'll see how they react to the nitrogen feed, think it's the major problem now..
Really hope that they recover, thank you guys you're saving me

 

[cbdthc01010]

I'm back, no signs of things getting better so I decided to try a small and light flush with pHed water at around 6.5 with just 10L of water (pots are 12L but not filled to the top with dirt).

Then I gave them some water with nutes (2ml/L of BioVega which I checked and it's NPK 3.5-1-5.5 and 2ml/L of BioFlores which is NPK 2.5-2-5) should I continue feeding them?
I can spot many more purple stems now and that's P deficiency if I well understood ..

Here's a picture, how many weeks do you think they can still survive? I know my harvest will be descrete but at least better than nothing

 

[Weaselcracker]

Based on the nutrient ratios I've been using for the last few years, those seem like grow nutrients to me, not bloom formula. Too much N, low P, and a weird ratio altogether. Do you have more info about the nutes you're giving her?

 

[KingstonRabbi]

Weaselcracker can correct me if I'm wrong, but I think the high K level may be interfering with uptake of Calcium and/or Magnesium. I don't see signs of Phosphorus deficiency yet but you may see it soon. The purple stems would be due to low magnesium.

I would use 1-2 tablespoons of epsom salts (in any drug or grocery store) for Magnesium and also Sulfur that may help. I would also replace the BioVega with something higher in P and with as little K as possible. Preferably one than contains amoniacal N (better for reproduction).

Again, I'm thinking out loud here. Focusing on how to get your plant to the finish more than correct past problems.

 

[Weaselcracker]

I am really not a deficiency expert. I'm not sure there even is such a thing really, though there are definitely growers more knowledgeable about it than I am. Including probably Kingstonrabbi Things get compounded so quickly, root systems and foliage are compromised in these situations, and trying to unravel the mess is nearly impossible. I generally just try to get the environment back into a healthy zone and wait for things to straighten out. You can flush if things are very bad, as long as you replace what is flushed out, with a good nutrient mix containing any necessary supplements.
Epsom salts won't hurt. I do question the amount. The stuff is strong. Even a teaspoon/gallon of Epsom salts is about ten times the amount you will find in the recommended dosage of Calmag supplement. It does seem like people get away with it though, so it must be hard to OD on magnesium.
I may start a thread about Epsom salts dosage because it's something I've wondered about for some time.
5ml of Epsom salts/gallon bumps the ppm up by 400. Whereas 5 ml/gallon of bottled Calmag is about 40 ppm of magnesium.

 

[KingstonRabbi]

Sorry, I was thinking larger bucket, not 11L.

As top dressing up to 1 tablespoon of epsom. You can do less if you're concerned, but I've done that with 2 gallon pots. As top dressing it works into soil gradually. I don't mix it into water.

 

[cbdthc01010]

I've looked around on the internet and it could really be a K toxicity that leads to Ca/Mg/Fe deficiency and N lockout;
so the light flush I gave them should have helped removing the excess but not too much because of the nutes I reinserted into the soil.

I will also follow your advice and give some epsom salts as soon as I can get them!

I'll keep you updated and still, many thanks for the help