I have a paph, that has a streak of bright yellow in the center leaf. I repotted and split it so I could treat the two differently. The yellow is not I'm dying yellow but a bright sunshine yellow. Looks perfect otherwise, roots and all. It's been this way for almost a month. I'll post pics as soon as the sun comes up. Any ideas?
the leaf was damaged in some way while splitting....it might have been too close to the rhizome cut or the roots got damaged....sorry, hopefully its an old fan thats previously bloomed....gl
From some e-mails I'm getting this is a nutrient deficiency resulting from switching to RO water this summer. Just need to add some nutrients and it should improve, I'll keep you posted.
In the photo I can see traces of it throughout the most of the plant so likely more than sunburn.
If you aren't using any plant food that would likely explain it. Even with regular water, they need some supplement occasionally and R/O is pretty much stripped of everything. It's a living thing and needs to eat!