Eddie Plesa Jr. has been at Calder Casino and Race Course since the first horses hoofprints there. When the Miami Gardens track opened in 1971, his father was among the first trainers to set up shop.

Later, Plesa followed in his father’s footsteps, became one of the track’s top trainers, and supported the place in 1989 when it prevailed in a head-to-head racing battle against Hialeah — the only time in South Florida history that two of its three tracks ran concurrently.

“It was good to my parents,” Plesa said of Calder. “It’s been good to me.”

But Plesa’s long allegiance with Calder could soon end.

Unless a compromise is reached between Calder and Gulfstream Park, the two tracks will battle nose-to-nose starting July 6, a showdown that will force most trainers to choose sides.

“It is the talk in the trenches every day, every minute of the morning,” said trainer Phil Gleaves, who bases his 10-horse racing outfit at Calder. “Everyone is saying: ’What’s going to happen? What are we going to do?’ “

Said trainer David Fawkes, who also keeps his horses at Calder: “I know a lot of trainers are concerned.”

For more than 40 years, Calder has served as the year-round base for hundreds of trainers and jockeys and up to 1,800 horses. While Gulfstream (and, at one time, Hialeah) raced the prime winter dates as seasonal tracks, Calder — South Florida’s “summer track” — was left alone the rest of the year. Hialeah now runs quarter horses for two months in the winter.

If the tracks stick with a new dates proposal, that will no longer be the case. Starting July 6, Hallandale’s Gulfstream intends to race on Saturdays and Sundays, putting it in direct competition with Calder, which plans to race on Fridays, as well.

“Gulfstream is clearly the aggressor on this all-out assault against Calder,” said John Marshall, Calder’s vice president and general manager of racing.

Said Gulfstream president Tim Ritvo: “It comes down to the horsemen.”

Or, more specifically, the horses.

Traditionally, there have not been enough of them to support two tracks at once. South Florida’s horse population swells in the winter when trainers from the north ship horses in to race at Gulfstream, which is owned by The Stronach Group, whose chairman, Frank Stronach, is a prominent thoroughbred owner, breeder and track operator. But they always head back about the first of April, leaving behind only the “Calder horses.”

While Gulfstream expects to convince some northern-based trainers to remain on site this year, at least with a small string, it will still be dependent on Calder horses to succeed. For that matter, even during the lucrative winter season, Gulfstream could not operate successfully without Calder horses, which make up about 60 percent of the entries that fill the daily cards at the Hallandale oval.

Battle lines are already being drawn.

“Calder supporting Gulfstream, those days have come to an end,” said Calder’s Marshall. “Calder is no longer going to support Gulfstream’s race meet like it has for 40 years. Gulfstream is not going to have that luxury anymore.”

To ensure that, Marshall said any Calder horses that leave to race at Gulfstream won’t be allowed back.