HELP! Sugar leaf trichs browing very early - Oh no! Also unusual yellow leaf edges.

[MadMike]

Grow Set Up:

Zazzy Grow Tent 48" x 32" x 60" (Nice tent!)

Viparspectra 300w x2
Viparspectra 600w x2
Maxisun 300w x1

General Hydroponics Nutrients
Coco and Perlite Medium
pH in is 6.0, pH out has been 5.8-6.0 for last few weeks

Temp - 75/69 day/night
Humidity - Averages mid 50's

Day 27 of flowering

Photo of Room



Six plants - From Left to Right
Back Row - OG Kush, Bubba's Gift, Blue Dream
Front Row - Jack Herer, Chemdog, Amherst Sour Diesel

Lights are Viparspectra's 300w on left side, Maxisun in middle and Viparspectra 600w on right.
The 300w's are running full veg n bloom, the Maxisun is full bloom and 50% veg, and 600w is full veg and bloom with shade cloth for area directly under light.

Quick History -
Plants had a hard slog from seed to light switch. pH was wildly out of wack when small and persisted for some time causing widespread leaf damage. Damage appeared to be K deficiency leading to browning edges and leaf tips. Once pH was finally stabilized the problem when away and I felt ok switching the light sched. You can see remnants of the damage in many of the older leaves. Up until 2 weeks ago I had been flushing first for each watering and then adding nutes for last amount water -- this was to restore the pH out to 5.5 - 6.5. I have had some nute burn as shown on leaf tips but I got that under control about a week or two ago.
Not best practice I know, but it did fix the problem and plants started growing great. And I've been doing some reading recently that definitely says not best practice. (Reference to article at end.)
However...

Current Nutrient Details -

I've been giving them 1/2 str GH Mid Bloom ratio with heavy runoff - Perhaps 20-25% every other day on average for last 2 weeks. Pots in the back dry quicker than front so give them a touch of water in between.
I just got an EC meter yesterday, (Finally!) and nutrient mix read 1090 μS/cm2 or so. That's low considering my water is about 300 - new to me and unfortunate... But I ain't got cash or space for an RO system right now. Interestingly the EC out of the pots was 850 μS/cm2 so that shouldn't be a problem but it does indicate I don't have a big salt buildup.
Also have been adding a touch of Yucca and Humic Acid each watering. I have been changing my watering a bit lately but I'll mention that in problem three below.

Problems -

Three main issues in different areas of room. One is early browning of trichs on leaves - left rear side. One is yellowing of leaf margins where trichs are forming - center. One is purple fringing on leaves - right front.



Biggest concern is the browning trichs -

I've had this happen before in my last grow and those plants had a few stressors on them, mainly pH issues. I also thought it might be from too much light but those two seem to play together. The plant is stressed, it can't handle too much light. I ran those plants around 400 micromoles and even less right at the end. Definitely hurt the harvest.

This grow however the plants have been running really strong since the light switch and some areas are running as high as 600, 700, or even 800+ micromoles and seem o.k. Well, sort of..
The OG Kush (back left) is showing the browning trichs on sugar leaves and the Jack Herer (front left) will do so shortly I expect based on the last grow. The buds themselves don't get brown trichs however and seem to mature fine but I believe the terpenes took a huge hit last grow based on odor and taste after cured.

I've done a ton of searching and I can't find anyone discussing this symptom? My plan is to turn down the lighting a touch and see if it helps at all. I would think stress on the plants would encourage this (I think??) but there are no problems with the plants that I can see. They don't show any of the typical signs of light burn - yellowing center of leaves, leaves curled up, etc.

You can see the amber trichs on these sugar leaves.



Second Concern is Yellowing Fringes -



Bubba's Gift (center rear) has been showing this symptom for a while and I thought it might be a trait for the strain. Where the sugar leaves are producing trichs, the underlying leaf is gaining a yellow cast. It makes them look creamy and delicious but I think it's getting too creamy now. I suspect this is light stress but the intensity over this plant is much lower than elsewhere in the tent. Averages 400-500 micromoles. However, the yellow cast is strongest where the light is strongest. The effect is unusual for me but I have never grown this strain before. Chemdog (front center) is also picking up a tinge of this now, and it's a new strain for me as well. The Chemdog looks like it's going to be nutty with crystals when all is said and done.

Similar plan to above is to lower light levels. I don't want to lower the levels below 400 though as it just doesn't seem like enough light, so I hope there are some stressors I'm missing/can fix instead.


Third Concern is Purple Fringing.


This is familiar to me but I didn't expect to see it anymore. The fringing looks like early K deficiency and this plant, Amherst Sour Diesel (front right), has struggled a fair amount with this early on. pH was an issue but I also realized that that pot was staying wetter longer than the other plants. It's an artifact of the air flow and place in the tent. I've since beefed up the circulation but it's still a damp corner. I began letting it dry out more between waterings and it seemed to help quite a bit. The pH is solid in the 5.8-6.0 out of the pot right now.

However, I recently read that watering should be consistent to maintain an even EC value in the coco coir and letting the coco dry out should be avoided. So I've been watering more frequently and the problem has shown up again. I think letting the pot dry out between waterings will fix this based on how things have been going for the past month so I'm not too worried about it. But I included it since I'm already here.



--- What are your thoughts on any of the above? Right now the crop is looking the best I've grown to date and I'm desperate to not have some crappy problem come in now and ruin it. It occurs to me that my nutes are a bit low and upping them might help with the yellowing for the Bubba's Gift and Chemdog. I'll be trying that out tomorrow.

Oh, and thank you tons for what ever help you can offer!


Reference on EC and Fertigation -
This article was a bit of a head turner for me since it explained several things I'd not seen mentioned before and was more comprehensive than any other resource I've found to date.
https://cocoforcannabis.com/principl...cannabis-coco/




** Aside - The Blue Dream is more sativa dominant than I have ever grown and it's totally a new beast to me. Stretched like a bitch and now the buds are developing very slowly. It's been handling more light than any of the other plants though and seems good with it. Very strange. Almost feels like an alien in the room.

[Peebz]

Hey man. Really good post and very informative. Good read for a rookie grower like me.

I certainly can't comment on a lot of your issues .but one thing I noticed is all my plants have turned purple by the end from letting them get to cold. You said it's a damp/corner and you needed better air flow. I also seen your temps between 69F and 75F. which to me is low. Iv always done my best to stay above 72. One night of sub 70f temps my ladies start turning purple.

If your air circulation is low and it's a damp corner it cold be getting cold at night time dropping bellow 69F

Hope you get some answers to the rest of it.

[MadMike]

That's an interesting point about the temp in that corner. I'll move my thermometer over their and see how to does for a day or two. Thanks for the idea, and will post results.

[Mr.furley]

"However, I recently read that watering should be consistent to maintain an even EC value in the coco coir and letting the coco dry out should be avoided. So I've been watering more frequently and the problem has shown up again"

Looks like a touch of Nute burn as well.

[MadMike]

Yeah, as I mentioned I did have some nute burn a while ago. You can see in the newest leaves that it's under control at the moment. Always 'at the moment...'.

[MBVapester]

Great grow. Subbed as would like to see some answers as well. Agree with the tip nute burn thought. I have the same issue but growing in hydro and too many strains to keep them all happy.

[MadMike]

It definitely makes it a challenge with so many different plants in the room at the same time. But I always want the variety. That Blue Dream in the back right is going to take much longer to finish than the rest. It's going to be tricky to harvest since I'm scrog-ing it and I have so many branches twisted under and over so many others that it will take a little surgery to get out the early birds.

[MadMike]

Made some changes over the last couple of days. I am using a Hydrofarm Quantum meter for my light measurements and I have always wondered about it's accuracy. Luckily I was finally able to find a comparison video against an Apogee which is pretty much the standard. Low and behold, the Hydrofarm reads lower levels and doesn't pick up light coming from the sides well at all. You can see the video here is your interested.

https://www.youtube.com/watch?v=_H8sDFECfA4

This means that when my Hydrofarm is reading 600 mmoles and a lot of that light is coming in from the sides as well -- I have multiple lights giving a more even coverage -- then the actual light levels might be as high as 750, 850 or more. So it seems very likely I have been drowning my plants in too much light. This would explain the sort of light burn look of the yellowing leaves, browning trichs and the stress on the Amherst Sour Diesel that is showing as a potassium deficiency.

Plus I finally realized my Blue Dream is foxtailing. It's such a different looking plant I didn't recognize it but that would also be caused by light levels and that plant was taking the highest readings in the room by far.

So I have lowered all the light levels to the mid 300's or so across most of the tent and it's around 450 mmoles under the shade cloth but I can't easily lower those levels more. It was reading 800+ in some areas under the 'shade' before so that's a whopping decrease. I estimate that a reading at 350 mmoles for exposure is more likely to be 500-550+ mmoles in actuality.

The camera settings are the same from the last photos so you can see just how much dimmer the room is right now.

I mark leaves by snipping of the tips of the center leaflets and that way I can monitor if the problems are spreading or getting better.


I took an unusual step and topped my biggest foxtailing buds on the Blue Dream so it would fill out better. Lower height also reduces it's light exposure a little. We'll see.

Here you can see the topped (left and right) and untopped buds.

Current look of room.


Oh, I also upped my nutes to 1200 EC and they got some more tip burn. Moving it down to 950 or so for right now and will see how things progress over the next couple of days.

[Sheesh]

Looks like some tip burn to me and maybe light height. One idea is to flush to remove salts and then reduce EC/PPM for awhile to see if it helps. One thing I didn't see in your write up was light height. Wondering if the pistils browning could be the lights being too close? I think most LEDs do well in flower at 18-24 inches but some LEDs require 24-30 or more inches above the canopy.

[MadMike]

Your question is spot on. My lights are a not high enough and the light levels are too high. Nice thing about the 300w's (Vipar and Maxi) is that they have dimmers so I have tuned the lights down a lot. I think I see improvements already. Yeah! The 600w is definitely too close so I shut off the veg lights and with the shade cloth it takes the light down right under it quite a bit.
I would raise the lights more but with a 60" tent I don't have any more head room. I'm planning on setting up another room and move the 600w to that. I'm torn about whether to replace it with another 300w with dimmers or just go with the three 300w's. I like the even light coverage I'd get with 4 300w's. Going with three I'm worried about too much light under the centers of them when I turn them up to better light the wall edges and corners.
I wish I had a diffuser I could mount under the lights to direct some of the center lighting to the sides -- I've seen one designed for HID's, sort of a reflective angle iron shape with holes in it. I tried to make one myself with cardboard and mylar in the past with poor results. I might try it again. With that I would be more confident running the 3 300w's in the room and get better even light coverage.
One note: The Maxisun is more powerful than the viparspectras I think but it has some hot spots in the center where individual leds seem to be concentrated. Sort of like spotlights in the center. It makes a hot spot of light. A reflector would help with that for sure. And I appreciate the higher output of the Maxisum, and.. Viparspectra discontinued the individual veg/grow dimmable variation in 300w.

[MadMike]

I should have also added that this grow got away from me in veg so the plants are larger than normal. That has impacted my head space for the lights negatively. Next grow, shorter plants.

[MadMike]

Things are looking better but I don't feel confident that they are fixed just yet.
I've tuned down the lighting a bit more so the Hydrofarm meter reads around 350 mmoles for most of the tent with lower values along the walls. It seems hard to believe but I think it might still be too bright in some areas. *shrug*

I adjusted the shade screen under the 600w to reduce the light in that area a touch more. I plan on replacing that light in the near future.

The yellowing on the Bubba's Gift might be getting better. It's not getting worse at least and I'll take that for now. New leaves look to have better color.

I topped a couple more of the Blue Dream buds that were foxtailing badly. I left a couple so I could compare their growth. It's such a weird plant to me that I don't really understand what a 'good bud' on that plant looks like.

Topped:

UnTopped;
I can't tell if they have stopped foxtailing since there are a couple that look like this. Watching them closely...


Purple fringing on the the Amherst Sour Diesel leaves hasn 't gone away but I don't see any actual damage to the tissue yet. I'm watching it very closely and might add a touch of a potassium boost in the nute mix soon.

Browning trichs seem to be holding steady with a few new ones popping up still. I think that the trichs are damaged from the light and end up with a shorter lifespan/quicker ripening so I expect some more to show up for the next week or two. Newest leaves will be most important to watch but it's a slow process to add sugar leaves to the buds.

I didn't mention that I have a fungus gnat problem and I haven't been able to get it eradicated. That might be wishful thinking. I applied a drench of Spinosad during the late veg stage and have been applying bt periodically. I laid down a carpet of fungus gnat sticky yellow cards and had them down to almost none. Moving the cards every day to water, and inspecting them for new gnats takes time and I thought the bt had it under control. No dice. They are increasing again so cards go back out. I actually had more than these in the room before so I might be adding some more than shown below.

[MadMike]

The reduced lighting seems to be helping. Browning trichs seem to be abating and the yellow fringing of Bubba's Gift is improving. I had some realization on how much light to give the plants when I went back and looked at the mmole graph/picture for the Viparspectra lights. They show around 450 mmoles under the center of the light (at a certain height). So, that should be a target reading.
I had read somewhere in the past and somewhere on the web that cannabis can take around 800mmoles during flowering. That was some of my drive to increase the exposure. Now, aiming for 400 or so seems to make sense and assuming my meter is reading 100 mmoles too low, I'm in the 430-460 range for most of the tent.

Other interesting 'problem'. The foxtailing of the Blue Dream seems to be continuing even with the reduced light. I've topped some but others I've let go to see if the foxtailing will stop on it's own. I'm wondering if some hormonal cascade triggers foxtailing and then it won't stop no matter what growing conditions are changed. I'm watching it eagerly to see what happens just from an experimental perspective.

I'll put up some photos of the Blue Dream next post.