Did the purple paint law pass recently?
I haven't heard anything about it here. It would make posting much easier. And cheaper.
Regarding statutes, I'm not a lawyer so this isn't legal advice -
You are technically trespassing in the 3rd degree on land that's not posted. Whether the police and prosecutor in your area will proceed with charges in that case is another question. They usually require one warning to be given, verbal or written. Lots of other factors play in - what were they doing there, what was their intent, was it at night, were they armed or have "burglary tools", is it in the middle of nowhere with no fences or signs, or is a residence nearby, etc, etc.
2nd degree criminal trespass is generally used after a warning has been given. This CAN include posted signage, but again, the police and prosecutor will make that decision.
1st degree is for trespass inside a building.
The key point here is it's best if you have property posted, and you're much better off especially if you DOCUMENT the trespass warnings that you give out.