Backyard Aquaponics
A place to discuss aquaponics

I have basils. They are growing pretty well but I've noticed that stems are rotting (it's really dark and blackish). I saw some leaf and has blackish color on the leaf.

Do you guys have any idea what's going on with the basil plant.
Thank you.

If the stems are rotting at the very base of the plant, the water level is too high so simply pull the plant up a bit, or lower the water level in the GB (which will affect all the other plants) so only the roots are getting wet and not the stem itself.

If the blackened leaves are on the "weather side" of the plant, they might have been affected by cold so protect the plant from "extremes" with some plastic sheeting or similar. Otherwise, black leaves can also be caused by a potassium deficiency, so add some seasol/maxicrop for a quick boost and bury a banana skin the GB for longer term resolution (add a handful of worms with the banana skin too).

If the problem is actually a disease/parasite, and for just in case anyway, remove any affected leaves now and throw them in the bin, not in the compost.

Thank you for the post. That's very helpful.

what do you mean by "weather side"?

also, the picture below is also caused by the stem rot as well? I don't know what brown/dark things are on the stems.

Also, I have these squash plants which have brown dying leaves.
Are those possibly due to the lack of potassium as well?

I've had basil get black on the stems but that seems to be the start of woody growth in my experience, I've go basil with bark on it's trunk instead of a stem.

I've also had basil get those black spots on its leaves and I'm not quite sure if it is due to lack of potassium or a fungal disease or if maybe the fungal disease is caused by a lack of potassium. But seaweed extract seems to help. And powdery mildew tends to attack squash plants that are suffering potassium deficiency too.