Blum stopped the timer at 33,64 seconden, staying ahead of Henrik von Eckermann with the 15-year-old Belgian Warmblood gelding, Cantinero (by Cento).
The Swedish show jumper crossed the finish in 35,24 seconds, while Marcus Ehning placed third with Cristy (by Canturo).
The top five was completed by Pénélope Leprévost (Urano de Cartigny, by Diamant de Semilly) and Jur Vrieling (Quality FZ, by Quintender).
Click here for the results