Pistils turning brown too early on one branch?

This is my first time growing, ive done alot of research and consider myself somewhat educated on growing but ive run into a problem with my plant growing outdoors.The pistils on one branch are turning brown prematurely. The rest of the plant looks great its just the one branch. What could the problem be?
Bad Branch

Good Flowers

Possibly russet mites but I'm not 100% sure

Does that branch get more or less sun than the rest of the plant?

I've seen one branch of pistols turn brown after I purposely pollinated her. Any other plants in the area?

@tannersmokin247 Ill check for them, thanks
@Final Phase Somewhat but there is a branch that gets less light and the flowers look fine on that one.
@Moldy No, not unless someone else is growing in the area