Okay here is the deal. I love my wife so very very much. The problem is when I am trying to do something like feed our son, she has to come in and take over the situation. Today I had my son eating his lunch. He was saying he did not want to eat his hot dog. I told him for each piece of hot dog he ate he would get a fruit snack. Well my wife comes in and dumps a pile of them on his tray. I told her I was having him eat one piece of hot dog to get a fruit snack. She states "well I want him to get vitamins and they are healthier for him than a hot dog." Is it wrong for me to say "When I am feeding him let me do it my way, when you feed him do it your way." It seems to me she totally undermined what I was trying to do. Please give me some feedback.

At the beginning of reading this my first thoughts were she is undermining you as you said at the end. She needs to respect your quality time with your son.
You need to find a time when the two of you are not busy and discuss this completely with her how you feel it is disrespectful and undermining and she needs to give you your quality time without interference. Tell her that as insignificant as feeding him hot dogs may seem to her it is YOUR (quality) time with him.
Maybe you could discuss all the main points that are important to each of you and make a chart you both agree on including things like balanced meals you both agree on.

She needs to respect your time with your son and not undermine you. Fruit snacks are not that much more nutritious for her to make an issue out of it like that.

I would say that you need to sit your wife down and have a talk with her. (not while your son is around) Let her know how you feel.
When my daughter was born, my husband could not do anything right. Well, in my mind anyway. I was constantly correcting him or taking over.
With your child eating hot dogs, I am thinking he is a little older? Has she always been like this?

Again, communicate with your wife. Let her know how you feel. She may not even realize what she is doing and how it is making you feel.