Falk leads Washington State over Oregon State 52-31
The pass attack also suffered, as freshman quarterback Seth Collins completed 17 of 30 passes for 176 yards, but was intercepted twice.
Washington State quarterback Luke Falk tied a team record with six touchdown passes, but all came in the first half.
The Cougars scored on all seven of their first-half possessions and piled up 520 yards of offense.
Falk, who threw for 505 yards and five touchdowns at Oregon, came into the game leading the Pac-12 in passing at 396 yards per game, and has thrown 21 touchdown passes with just four picks this season.
Washington State's Tavares Martin Jr. returned the opening kickoff 51 yards and the Cougars marched down the field, with Falk throwing a 3-yard touchdown pass to River Cracraft.
After a touchdown pass to Marks was called back for offensive interference, the Cougars had to settle for a 30-yard field goal by Erik Powell and a 24-3 lead.
Oregon State's Victor Bolden returned the ensuing kickoff 100 yards down the right sideline to cut the WSU lead to 24-10.
After an OSU punt, Washington State drove 69 yards, with Falk throwing a 22-yard touchdown pass to Morrow for a 38-10 lead.