Father daughter conflict

How can I make peace between my husband and our teenage daughter? Every day when he picks her up from school he either starts a fight or delivers a lecture about how she's not measuring up academically. Then she calls me, angry or in tears. Grades have always been a problem for our daughter, and I understand that we need to do everything we can to encourage her to stay on top of her schoolwork. But at this point her dad is just making her feel like she's not "good enough." Can you help me?