yellow leaves and brown spots....oh my

[wienstien]

A couple of the big fan leaves have turned this yellow color.
its not all the leaves either, just a couple....what could be the problem?
how much should i worry? im about 3 weeks into flowering
using fox farms nutes and schedule

 

[mndovrmtr420]

Some varieties change color like that. Cant tell if thats a bronzey tone im seein or not. What strain is this? how long flower time?

 

[joseaf]

I had a simuliar problem. I flush the system and added the recommended nutez. I also added Epsom salt to the solution. 1tsp per gallon.