Week 5 Flower: Help with diagnosing leaf problem

C

ctrev

Active Member
This is my first grow and I've got a few mainlined plants indoors that I started from bag seed. I'm in week 5 of flower and the leaf tips of the new top leaves around the colas are yellowing pretty badly and curling up at the ends. I think it might be a zinc deficiency but I'd like a second opinion.

I'm using the fox farms trio in FFOF soil and began the full strength nute schedule a couple weeks ago. The plants are about 12" from a 600W hps in a cool tube with a 400cfm fan. Temps stay between 58 and 70. A few days ago I tried flower's kiss foliar spray because of the .5% Zn but it hasn't helped yet. Also wondering if it could be light burn. It is primarily affecting the tallest colas. All the lower leaves are healthy and green. Here's a couple pics.

yellowing.jpg

yellowingsideview.jpg

yellowing2.jpg

Thanks.
 
Cascadian

Cascadian

Well-Known Member
I went straight to looking at the pics and my first thought was possible light burn. I am not familiar with zinc deficiency.

Have you measured your temps at the plant tops? Do you have good airflow like an oscillating fan in the room?

Just giving my impression, wait for some other opinions...
 
C

ctrev

Active Member
Thanks for the replies. I didn't think it could be light bleaching since i've got a foot between the light and canopy and temps stay under 75. I dimmed the ballast so hopefully that'll fix it.
 
tikitoker

tikitoker

Active Member
Genetics, maturity, pH, amount of light, temperature, and even available sugars can influence the color of cannabis. beautiful green of the cannabis plant wasn’t the only color present during the vegetative stage, but until the lengthening dark cycle triggers the plant to stop production of the green chlorophyll, we can’t begin to see the yellow and gold color of the carotenoids. It is perfectly natural for cannabis leaves to change colors and die off as the plants reach their “autumn” or finishing stage, showing varying shades of green, yellow, gold and more.
Some plants will turn red and purple as anthocyanins are produced using excess sugars in the leaves and spreading through cell fluids. The pH of the cell fluid determines the color variation, with an acidic fluid producing reddish hues, and an alkaline fluid producing blues. Cellular pH being genetically regulated, each strain has its own unique combination of chlorophyll and carotenoids and potential for anthocyanins production, giving a great splash of color to a diversified grow as nights grow longer and temperature cools. Many strain’s color range is limited exclusively to greens and yellows through the life cycle.
 
Liddle

Liddle

Well-Known Member
ctrev said:
Thanks for the replies. I didn't think it could be light bleaching since i've got a foot between the light and canopy and temps stay under 75. I dimmed the ballast so hopefully that'll fix it.
Click to expand...
turn you ballast back up! its something else. 75 temp is great.
 
kagecog

kagecog

Well-Known Member
Hmm looks to me more like the early stages of potassium deficiency, it can be common in peat based mediums such as FFOF later in flowering because the pH tends to go down dramatically as the peat moss ages. Try adding some lime to the soil to raise the pH a bit. It can also be caused by having too much salts or calcium in your soil so i'd recommend flushing your soil as well. Looks nothing like a mag deficiency to be honest, closer to what you would experience from having too much mag if anything. Also, stop with the tiger bloom, that shit is like poison to plants in my experience, big bloom and grow big are fine though, just cut your dosage to half of what they recommend on the bottle. Definitely dont have to worry about light bleaching with a 600watt, you'd need quadruple that wattage before you could even BEGIN to think about that. Also, you haven't been overwatering right? Make sure to let your soil dry almost completely before the next watering
 
C

ctrev

Active Member
I didn't think it was light burn either. Turned the ballast back up. I always let the soil dry between waterings. Next time I'll flush and add a little dolomite lime. Maybe reduce the tiger bloom and I ordered a PH test kit.

Also, they've been in the same five gallon pots for a little over 2 months now so maybe that has something to do with it. The soil not being able to buffer the PH as much anymore.

Here's a pic of one of the colas on another plant starting to get a similar looking symptom on leaves further down from the top:

yellowing3.jpg
 
C

ctrev

Active Member
When I flushed I took some pH readings using general hydroponics' liquid pH test. My tap water was 7.5 or 8 and the runoff from the plant was 7. I also took a soil sample and used it with a rapitest soil ph kit. It also showed 7. Could my pH be too high? Hopefully they just needed a good flush.
 
tikitoker

tikitoker

Active Member
7 is neutral, and within range. however you could be a tad lower and most likely are. try a flush but IDK, it looks like K deficiency. Either way, fuck all this non-sense on what's deficient. flush, and re-dose complete nutes. if that don't work, I don't know what to tell you.....fuck it.
 
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