The Terps fall to 5-9 with their losses on Sunday.
Both teams combined for five home runs Saturday night.
Cowles has seven home runs and 16 RBIs in 11 games this season.
The Terps scored two runs in the top of the ninth to tie the game up. They weren't enough.
The Terps' 19 runs are the most they've scored in a conference game since joining the Big Ten.
The shortstop slugged five home runs in the weekend series against Rutgers.
The Terps didn't look back after scoring three runs in the first inning.
The Scarlet Knights combined for 17 runs and 21 hits across Saturday's doubleheader.
The Terps fought their way out of a 3-0 hole.
The Spartans rallied from four runs down in the second game to secure a series victory.