Pianalto injured his right leg at the ankle joint while being tackled in the second quarter of Saturday's game at Virginia.
"He has a fractured fibula and he will be out for the season," Davis said during his Monday press conference. Pianalto will undergo additional evaluation this week to determine if surgery is required.
When asked if there was a chance of a recovery in time for a bowl game, Davis responded: "I don't know right know - don't know how long it takes bones to mend."
The Springdale, Ark. native is UNC's leading receiver in 2010, with 30 receptions for 311 yards.
He was selected in the preseason to the 2010 John Mackey Award Watch List, given annually to the nation's top tight end.
"He's our leading receiver this year, both in yards and receptions, so I think that speaks to the fact of how valuable he is to this offense," Davis said.
Pianalto earned Honorable Mention All-ACC honors in 2009 after setting a school record for most receptions by a tight end.
His Tar Heel career has been plagued by injuries. He missed six games his sophomore season as a result of a fractured left fibula and later a right ankle sprain, and then missed five games his junior year after dislocating his right foot.
Pianalto's career totals over the past four seasons at UNC include 26 starts, 94 receptions (a school record for a tight end) and 918 yards.
"It's really a shame," Davis said. "He is such a terrific kid. There's almost nobody in this program that puts more heart and soul into playing and preparing and practicing and goes out there and plays as hard as he does. "It's certainly a loss for this football team."
North Carolina's depth chart for this coming Saturday's game at Miami lists Ed Barham and Nelson Hurst on the tight end two-deep, with Ryan Taylor and Christian Wilson at H-back.
"We've got to try and find a way to manufacture catches and yards from somebody else," Davis said. "We'll just try to see who we can add, if we'll stay with those kind of personnel groupings or we may go four wide receivers this week."