Strange Def. and How long to go till harvest ?

This is almost a month to flowering. Today I realized pistils started to get brown. I m using 600w hps

Happened to me on one budsite.. the light slipped and got too close.. not saying that's what happened here.. but if its not on every budsite it could be that its too close..
On my first grow 4th week into flower so I'm no expert. But good luck

Thanks for giving an idea