TCB,
I wish I could give you something comprehensive, but although I was born and raised in Ohio, I’ve lived in Ca for over 30 years now and am not familiar enough with back there to offer many specifics. However, I can offer a few things, for whatever they’re worth.
The best thing you can do to get specifics is to either get to know the head greenskeeper at the best local country club and ask him, or if you have a local university that does a lot of work in agronomy and such, and contact them for help.
One of the easiest ways to control, not eradicate but control CG, is frequent mowings. CG reproduces by seed, so if the seed isn’t allowed to mature, it won’t spread so aggressively. And that brings up another “issue”. If you only treat the infield grass, chances are you’re gonna be pretty much wasting a lot of time and energy. Since CG propagates by seed, if there’s a bunch of CG between the dugouts and the IF, seeds are gonna get on shoes and be transferred to the IF grass.
The best control is to eradicate it all over the field, but I realize that might be an expensive proposition. A good alternative is to make sure you have a plan in place that keeps pre-emergent in place for the seasons when CG will sprout. Again, I could give you general times, but the best thing is to contact someone local who knows for sure.
As for overseeding, it CAN be a wonderful thing, but it CAN backfire. If you overseed with the wrong kind of grass, or use a cheap grade that has a high percentage of weeds in it, you can cause yourself more trouble than you started with. But, if you use the correct seed and a high grade of it, then follow the directions meticulously, it will rejuvenate your turf. And remember, healthy turf is always much better looking and easier to maintain. So don’t skimp on fertilizer, don’t over or under water, keep the mowings as frequent as possible, and make sure the mower blades are sharp.
Good luck!