Very doubtful it's disease, or it's neighbors in the growroom would likely be affected, too. What does the underside of the leaf look like?

To me, it looks like one of two things.

1) Have you used a magnifying glass to look for bugs on the undersides? (I doubt this is the cause, but I'd check anyway)

2) It looks like the larger injuries are possibly from leaf-tip irritation. When a fan blows the leaves (leaftips, for example) back-n-forth against another leaf, it can irritate the leaf being rubbed, it will cause a sore that looks similar to that, which will brown-up as the damaged part dies. Old injuries don't "heal", but new growth shouldn't be affected.

The browning of the smaller leaves kinda looks like a transplant injury or some other mishandling. Keep an eye on 'em and let us know if anything get's worse.
Rusty Trichome Reviewed by Rusty Trichome on . White spots Hey guys its my first post here, I just started my first grow and things are overall going pretty well. Ive done a lot of research but actually getting down and growing is a totally different thing. I was able to spot and notice nute burn in some of my plants, and have been only getting water for awhile now. The plants are still pretty young. In this one particular plant I just noticed this white spot on it. It does not look like the nutrient burn I am familiar with. I am inclined to say Rating: 5