Fernander, who improved his record to 8-2, allowed a leadoff single on the first pitch of the game and then retired 14 straight batters before giving up a single to start the sixth inning.
He walked two and struck out five.
Danny Madden retired the side in the eighth inning.
The Eagles, who had 14 hits in the game, broke a scoreless tie with three runs in the fourth.
Polk State added three runs in the sixth when Nico Limoncelli tripled home two runs and then scored on a wild pitch.
In the eighth, the Eagles plated four more runs for the run-rule win.
Trent Sinkfield scored on a double by Ashby. Limoncelli scored on a sacrifice fly by Miles Simington. Ashby came home on Koruschak's RBI single, and Danny Berg's bases loaded walk gave the Eagles a 10-0 win.
Limoncelli went 3-for-4 with a triple, a walk, a run, a stolen base, and two RBI.
Sinkfield doubled twice and scored a run.
Zach Scott went 3-for-5 with a run.
Ashby singled, doubled, walked, drove in a run and scored twice.
Koruschak went 2-for-4 with a double, a run, and three RBI.
Berg had a single, a walk, a run, and two RBI.
The Eagles (21-19, 8-10) travel to Bradenton Friday to play State College of Florida, Manatee-Sarasota at 6 p.m.