Shriveling leaf tip, diseased?

I have 2 plants, 3 weeks from seed, and there's this one lower leaf that has a dried up yellow-green tip. It doesn't look like it's dying off naturally, almost like a disease creeping up. Other parts of the plant look pretty much healthy. Should I cut it off?



Here's a wider shot. They're in Ocean Forest soil in 1-gallon smart pots.

i have read if 50% of a leaf is damaged they say cut/prune it off i have no experience at all just what i have read so not sure why that could be happening hope this helps