Evn with its winless record, Hawaii has a history of second-half rallies this season. But the Rainbow Warriors suffered a potential 14-pont swing late in the third quarter when USU linebacker Kyler Fackrell returned an interception 99 yards for a touchdown to make it 40-10.
Utah State produced points on five of its six possessions in the first half, taking a 23-3 lead.
Garretson hit Bruce Natson for an 11-yard touchdown and Joey DeMartino ran 4 yards for another Aggie score. Nick Diaz kicked field goals of 40 and 32 yards. Long-distance specialist Jake Thompson added a 52-yard field goal with 50 seconds remaining in the half.
In the first half, Hawaii countered only with a field goal on its first drive. USU halted two promising drives with Brian Suite's interception deep in Aggie territory and by stopping a fake-punt play near midfield.
Hawaii quarterback Sean Schroeder threw a 33-yard touchdown pass to Keith Kirkwood on the Rainbow Warriors' opening drive of the second half. USU answered with Diaz's 32-yard field goal and Garretson's 30-yard TD pass to Travis Reynolds to make it 33-10.
After Fackrell's touchdown, the Aggies added Garretson's 44-yard pass to tight end Wyatt Houston.