If there is something that is happening that is either a danger to the child, other children or my home and I feel that the parents can do something to support the lesson that I am teaching then I will tell them, but it's more of a "can you work on this because johnny has been doing this lately..."

I don't mention minor infractions that I've dealt with. Yesterday one child continually poked another with a fork at the table. I had to remove him and give him the option of either going right to bed or behaving properly at the table. He went back, ate his lunch and pouted all the way to nap time. No reason to tell mom. It was handled and kids will be kids.