Washington optioned Palmquist to Triple-A Rochester on Saturday.
Palmquist will head back to Rochester for the first time since June 29. The southpaw opened Tuesday's game against Philadelphia and lasted just one-third of an inning after giving up one run on two hits. In 16.1 innings this season, the 25-year-old owns a 7.71 ERA, 1.78 WHIP and 15:8 K:BB.