The couple owned Spurs of Counties, one of New Zealand's most prestigious saddlery stores which specialises in leading equestrian brands from around the world.
Sorrell announced the news of his wife's sudden death on Facebook.
"It is with a heavy heart that I advise you all that Tracey passed away yesterday after a tragic accident," he wrote.
"We appreciate all of your support and love. "
Blackmore-Sorrell had been competing in dressage for about 30 years and her death shocked the community.
International event rider and trainer Donna Smith said she was "absolutely devastated".
"Tracey was an amazing woman, with incredible passion for everything she set her mind to. Much love to Chris, Maddie and Hayley," she wrote on Facebook.
A post on the Dressage Clinics New Zealand Facebook - a community page for eventing enthusiasts - also paid tribute.
"Tracey was a passionate dressager and was in her third decade as a dressage competitor. Our condolences to Tracey's family."
Dressage Waitemata posted: "So sorry to hear this. Tracey will be missed from the dressage world. Sending love to Chris and the girls."
Blackmore-Sorrell was farewelled at the home of her mother, Marie, in Kumeu on Wednesday.
Her death notice described her as a soulmate to Sorrell, "adoring mother" to her daughters and a "beloved and precious daughter".
"Tracey lived life to the fullest, always with a smile on her face and will be sorely missed by us all," her family said.
They thanked the emergency and hospital staff for "their wonderful care and support" after the accident.
