Busternutt
Well-Known Member
Can anyone tell me what all the little lumps and bumps on the leaves are? 
What is going on with these leaves?
- Thread starter Busternutt
- Start date
iShatterBladderz
Well-Known Member
To me, it looks like where trichomes started coming in but are having trouble due to poor ventilation or heat stress. What are your temps and RH like? How often are you bringing fresh air in? What kind of light are you using and how close to the light is the plant?
Dumbguyneedshelp
Well-Known Member
Over feeding?
iShatterBladderz
Well-Known Member
It definitely does look like he’s been feeding too much N, but I don’t think I’ve ever seen N toxicity cause bumps like that. i could be wrong though, not afraid to admit it lol.
Dumbguyneedshelp
Well-Known Member
Def looks like trikes that are having trouble. Looks like a leaf I rubbed all of them off of one time lol. And looks like some nute burn
Busternutt
Well-Known Member
Thanks for the replies guys. I was overfeeding it (I'm pretty new to this) and I'm assuming the brown edges was nute burn but have it under control now. I had the EC way too high but everything's happy now.
Lights are LED and about 600mm above the plant. It's a stealth grow so can't go much higher (redesign after harvest). Fresh air comes in constantly and is drawn in from outside the building by 2 x 4" fans with a computer radiator in between them. An aquarium chiller cools a reservoir of water which is circulated through the radiator. I originally had the chilled air coming into the base of the cabinet, below the plant, then added some ducting and had the air running over the top of the plant but a week ago I moved the duct so that the chilled air runs across the underside of the LEDs. 2 x 4" Extractor fans also run constantly and I have ducting across from the intake air to the extractor fans so the incoming air runs across the the underside of the LEDs and is pulled back out of the cabinet. Temps dropped a little when I did that.
It's as hot as the sun here at the moment but during the day, I'm averaging around 32*C and 45% RH inside the cabinet and I also have a humidifier and a dehumidifier in there helping balance the RH.
Lights are LED and about 600mm above the plant. It's a stealth grow so can't go much higher (redesign after harvest). Fresh air comes in constantly and is drawn in from outside the building by 2 x 4" fans with a computer radiator in between them. An aquarium chiller cools a reservoir of water which is circulated through the radiator. I originally had the chilled air coming into the base of the cabinet, below the plant, then added some ducting and had the air running over the top of the plant but a week ago I moved the duct so that the chilled air runs across the underside of the LEDs. 2 x 4" Extractor fans also run constantly and I have ducting across from the intake air to the extractor fans so the incoming air runs across the the underside of the LEDs and is pulled back out of the cabinet. Temps dropped a little when I did that.
It's as hot as the sun here at the moment but during the day, I'm averaging around 32*C and 45% RH inside the cabinet and I also have a humidifier and a dehumidifier in there helping balance the RH.
iShatterBladderz
Well-Known Member
my guess is heat stress. That’s pretty warm, and IMO 45% Rh is too low for temps that high, even in flower, except for maybe the last week or so. The ideal solution would be to find a way to drop your temps. If not, I would bring up the humidity a bit. 45rh & 32 degrees Celsius would put your VPD (Vapor Pressure Deficit) somewhere above 2.0 and in flower, 1.3-1.5 is really ideal. If you’re not familiar with VPD, I definitely recommend doing a little research on it. Or if you go on YouTube, the dude grows show has done a few different videos on VPD.
iShatterBladderz
Well-Known Member
Here’s some good reading on VPD
Understanding VPD and Transpiration Rates for Cannabis Cultivation Operations
This article explores how vapor pressure differentials (VPD) affect transpiration rates in cannabis plants. Understanding of VPD at different temperatures and relative humidities, and its effect on this process, is important to gain maximum plant growth.
www.cannabissciencetech.com
Busternutt
Well-Known Member
Damn, never heard of VPD, lol. I can easily bring the humidity up though. Thanks, I'll have a read right now!
iShatterBladderz
Well-Known Member
Of course! If you don’t already have an IR temp gun, I would recommend getting one to read your leaf surface temps. They’re only about $15-20 USD on amazon or hardware stores. You can kind of guess until you get one though, usually under LEDs your leaf surface temp will be ~2 degrees F cooler than your ambient temps, but it can vary based on both airflow and light proximity, and that’s when a temp gun comes in handy.
once you do a little research, Pulse has a tool on their website where you can plug in all your specific metrics and it will generate a chart for you based on your metrics and which stage of growth you’re in.
sandman83
Well-Known Member
oh hey, my kitchen temp gun will finally come in handy somewhere??? VPD sounds like greek to me, back to the reading mobile.
Busternutt
Well-Known Member
Yes, I have a IR gun. What's the Pulse website? That sounds like a real handy tool! I read online (not this forum) about temps and humidity at various stages of the plant's life and basically, at the stage flower I'm at now, the article says this;
Flowering Period
- Humidity levels need to be lowered to 40-50% (extremely important)
- You can get away with 55% (anything over 60% is real bad)
- It’s best to slightly lower temperatures in flowering
So I was trying to do that and the temps and RH I quoted above are about the closest I can achieve to the figures in that article and I was worried about mold forming if I left the RH too high.
Using the charts in the article you linked, I've upped my RH to 70%. Fuck it, go big or go home, lol.
I'll report and changes I see. Thanks for your help
iShatterBladderz
Well-Known Member
A good foliar spray can help prevent PM. I use Optic Foliar Overgrow myself. Does your humidifier put out warm mist or cool mist? Just make sure to keep airflow running through your canopy, and if your buds are really thick, you may lower it a little even if the VPD checks out, as long as you don’t get too far away.
definitely watch your plants carefully, even with correct VPD, the temps are a bit warm. Different strains can handle the heat better than others. I typically try to keep my leaf temps under 82-83 degrees F, unless I’m adding co2. Although having your plant transpire efficiently does help it withstand higher temps easier. Supplementing your plants with silica can also help with this, but usually that’s something you’d start doing in Veg.
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An1m0ssity
Active Member
Honestly, it looks like leaf-septoria. I could be wrong because the spots do look a little small for that to be the case, but it looks extremely similar.
Attachments
iShatterBladderz
Well-Known Member
That’s a very mild picture of leaf septoria, if it is at all, any case I’ve seen has always been accompanied with very sickly looking leaves, as well as brown/black spots mixed in with the yellowing. Unless I misunderstood him, OP says the yellowing stopped whenever he adjusted his feed strength. If it was leaf septoria, it would progress and the leaves typically start to wither and/or die. I attached some better examples of how leaf septoria typically presents itself. At least, in my experience.
An1m0ssity
Active Member
That's interesting. I'm gonna have to jot that down in my journal. Yellow spotting could be caused from nutrient strength. Thanks for the heads up. Cheers
iShatterBladderz
Well-Known Member
If it was just random spots in The middle of the leaf, I wouldn’t think it could be nutrient burn, but the way it’s moving inwards from the outsides of the leaves, but is mostly on the tips, I definitely think it could be nutrient burn. It’s hard to say for sure but if it hasn’t progressed since he got his EC back under control, depending on how long it’s been since he got it under control, I would assume that’s what it was or at the very least, whatever caused it has also been corrected, even if naturally or unknowingly.That's interesting. I'm gonna have to jot that down in my journal. Yellow spotting could be caused from nutrient strength. Thanks for the heads up. Cheers
hellmutt bones
Well-Known Member
Nute burn. Check ph.
Busternutt
Well-Known Member
I think it was a combination of nute burn and heat stress as the leaves directly beneath the lights are worse than the leaves around the edges (of the grow area). I have my pH and EC sorted now and raised the lights and the burning hasn't got any worse.
What is PM iShatterBladderz? The humidifier puts out warm mist but it only feels warm directly in front of the outlet.
Strain is Amnesia Lemon. The grow cabinet is supposedly at 30*C at the moment but the leaves at the top of the heads read 26*C. I've set the humidity at 70%, which is roughly in keeping with the VPD chart. I've left the incoming chilled air running across the underside of the light as I have a little oscillating fan in the blowing on the plant.