Walker and Coralissa jumped to the top of the leaderboard against 62 other talented young riders on the Derby Field at WEF.
Show Jumping
Top Canadian in the class was Erynn Ballard riding Catoki's Son Z, who placed 4th in a large starting field of 66 on the grass Derby Field.
Less than a second separated the winner from runner-up Beezie Madden (USA) and her veteran partner Breitling LS.
Following 30 years of competition organization, EMG will turn over operations of the Caledon Equestrian Park to Angelstone Events.
Ashlee Bond (ISR) and Imagine out-galloped Canada's Erynn Ballard and Classic Penny to top a field of 40 over Catsy Cruz's (MEX) course.
Both Youth Championships will be hosted in Germany, with the Youth Jumping in Aachen and the U25 Dressage in Hagen.
The $1,000 bursaries for 14-17-year-olds are to be used for riding lessons, show fees, continuing education and other learning opportunities.
Canadians Eric Lamaze and Tiffany Foster place 5-6 in the class, while Rachel Cornacchia grabs 2nd place in $50,000 grand prix.
Week four of the Desert Circuit at DIHP wrapped up with a win for King; top Canadian was Brian Morton, who was 7th riding Crusador Z.
Two Canadians were top-10: Mario Deslauriers and Bardolina (7th) and Eric Lamaze with Dieu Merci Van T & L (10th).