don blaze

That happened to me recently. I think it's from the part of the leaf that would turn yellow while its rooting, but it was too humid and that part rotted. I cut those leaves off, but they didn't do too well. i think those clones were taken 2-3 wks into flower, which i usually avoid. That's my experience, but not much of a knowledgeable answer- my cloning abilities aren't much.

never clone the plant when its on the 12hr flowering time.... always before that.
and it sounds like it might be to humid where ever you are growing.
Also check for litte black flys called Fungus gnats... they live in the soil and they can really F up your plants roots.
i dont know if that helps.
J.

If it's mold it will generally have a little fuzz on it. And you should know about how humid it is. If your grow spot feels like the air is moist it's around 90%. If your growing in dirt the average humidity from watering should be about 45%. It could also be lack of phosphorus. Check your ph first, you can go to somewhere like OSH and get a cheap one for 10 bucks.
Good luck, happy growing