Necrosis
Pronounced / neh·KROH·sis /
The death of plant tissue, usually showing as dry brown patches.
Example in a sentence
“Once leaf margins turn crisp with necrosis, that dead tissue will not turn green again.”
Read more about Necrosis
Leaf Doctor
Purple stems and petioles: the phosphorus myth
Purple stems are not a reliable sign of phosphorus deficiency.
Leaf Doctor
Yellowing lower leaves: what it is, and when it’s nothing
Before anything else: if you're six or more weeks into flower and it's only the bottom leaves, this is probably normal.