Wickmayer raced to a 6-4 6-0 win in just 57 minutes.
The 22-year-old, who converted five of 11 break points, will play Israel's Shahar Peer in the last four.
The sixth seed led Anna Chakvetadze's 4-6 6-4 1-0 when the Russian was forced to retire.
Fourth seed Angelique Kerber will meet fellow German Mona Barthel in the other semi-final.
Kerber survived a second-set wobble to see off Romania's Sorana Cirstea 6-0 3-6 7-5, while Barthel ended Australian fifth seed Jarmila Gajdosova's hopes with a 2-6 6-3 6-2 success.