Maryland's assistant baseball coach, Ray (Red) Ruffing, greeted Towson State Coach Billy Hunter before yesterday's game, pointed a finger upward, felt the stiff northerly breeze and smiled. He looked out toward the short outfield fence at Shipley Field and said, "The balls will be jumping out of here like popcorn."

Hunter laughed then, but it was his ace pitcher who provided the popcorn.

The Terrapins (7-8) hit three home runs in the first three innings and received seven strong innings of pitching from right-hander Mike Lavin in a 13-3 victory at Shipley Field. They now have won 31 straight games at home.

Maryland left fielder Jimmy Brooks led the 15-hit offense with a single, two doubles and a two-run homer. He scored three times, the first on a three-run homer by third baseman Tim Gordon that gave Maryland a 3-1 lead. First baseman Dub Daniels, a last-minute starter for flu-stricken Craig Chase, hit a three-run homer in the third, putting the Terrapins ahead, 8-1.

Towson right-hander Steve Alcorn (12), his team's top starter this season with a 2.95 earned run average, lasted four innings, yielding eight hits, three walks and nine runs. His team was down eight runs when he was replaced.

The margin would have been less had Maryland center fielder Tony Larioni not made a one-out, fence-crashing catch in the first inning that turned designated hitter Brian Marden's grand slam into a sacrifice fly. Lavin then forced John Matheis to pop out, holding Towson State to one run.

The Tigers (5-6) did not score again off Lavin (1-2), who was unable to play last season because of arm trouble that has forced him to become a finesse pitcher. Lavin began to baffle Towson State batters with offspeed pitches, giving up two singles in his remaining six innings, helped by solid infield defense. Alan Alt pitched toe last two inings, allowing four hits and two runs.

Alcorn, struggling with his curve ball from the start, relied mostly on his fastball after constantly falling behind hitters. In the first, Brooks doubled, Larioni walked and Gordon homered on a 2-1 fastball. In the third, Bob Zavarick led off with a single and Brooks homered on a 2-1 curve ball. One out later, Gordon walked, Tom Weider singled and, after a pop out by Steve Johnson, the lone Terrapin starter not to reach base, Daniels homered to the opposite field on a 3-1 pitch.