Can anyone identify this disease?

Hello!!

So I’m growing a lot of these dianthus “fringed pink” from strictly medical seeds. All of them look great except this one… I’m not sure if it’s an insect or virus … let me know !!

Actually, both.  Some viruses are known to be transmitted via insects.  Control the insect and you can control the spread of the virus.

Like Michael, that was my first thought.  A virus spread by some sort of insect.

I would try using a spray like these recipes:

https://permies.com/t/93537/toxic-Fungicide

This may not help infected leaves though it might help new leaves.