If you only fertilize once a year, then this is the time to do it.  The plant starts to grow differently because the days have shortened up, the sun is losing its angle, and temperatures have started to slide.  Energy is sent to the roots to strengthen the system for the upcoming winter.  I was always taught that 2/3 of your nitrogen should be applied during fall applications.  However, that was in Indiana with a 8-9 month growing season, so the numbers may be a little different in California. 

The basic principal holds true that creating a stronger plant this time of year will result in better turf in spring and even in summer.  I hate the "Spring Green Up" campaigns that flood tv's just when the turf starts to release it's stored energy.  If you build a strong plant right now, you will not have to throw out fertilizer to promote more topgrowth.  Just like any other plant, turf is trying to get as much leaf tissue as possible in the spring.  More fertilizer during spring months means more mowing.  I hate mowing.  You should see my lawn right now. 

So fertilize now and benefit later.  That's what we are doing today, now that aerification is wrapping up and we can rotate machines on the tractors.  We've been very busy, but everything is going really well and the course will be back up to speed and rejuvenated in a few short weeks.