Leaves Turning Black?

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Hey there,
I have been reading posts on this site for about a year and was finally spurred to create an account when my plants had a problem I couldn't identify.

My setup was 4 plants being grown in coco, with drip irrigation and Botanicare nutes with an EC of 1.6 and a PH of 5.7. Two plants (Pineapple Chunks) have been harvested and the Liberty Haze sisters are the two remaining. They are at the very end of flowering and I want to start the flush (if this problem doesn't stop me)

The first picture here shows a leaf that appears to have black forming in a necrotic pattern. Using the resources on here and the Cannabis Encyclopedia I was not able to find the cause. Any help would be appreciated!

I would like to know if I need to fix it, or if I could flush for 1-2 weeks and ignore it.



This leaf appears to be affected by he same thing however it is just solid black or very very dark brown. This photo was more due to the difficulty of seeing color under HPS light.



Thanks!

Looks like thats just the natural fade of the phenotype. Some stay green all throughout flower and others fade to purple/brown/black in the last few weeks.

You need a pic of the whole plant and some feeding info.

that RED(black) is Anthocyanin or excess sugar

thats stalled in transit heading to the roots

to my blog : https://www.rollitup.org/Journal/Entry/understanding-red-stems.30159/

or better.. just keep up your temps more so at night

good luck

bbyb420: That was my original thought, but I have not seen any other Liberty hazes that have this color. Have you experienced this at all on the ones you are growing?

*Buds: I will try to catch them before the lights kick on. Its nearly impossible to see the colors of the leaf once the HPS kicks on for the day.

vostok: Thanks for that link! That definitely looks like what my plants have going on. There definitely could be excess sugar as I have been feeding them "Sweet" longer than I expected to, due to the length of flowering on these two plants. I will kick the night time temp up! Thanks again.