How to nullify visitation?

I am divorced and the custody of my son is with me, but the biological mother have visitation right. I am now remarried and my son is very well adjusted with the step mother. My ex wife has been poisoning my son's mind against my 'new' wife. And therefore, he become very confused, because my son really loves his 'new' mother. Is this a strong enough reason for me to move an application to the court, asking for removal of the biological mother's visitation right?