The Oak Tree Racing Association announced Thursday that it will increase the purse in the Lady's Secret Breeders' Cup Handicap (gr. II) to $300,000 guaranteed. The 1 1/16-mile event for fillies and mares will be run on Oak Tree's 0pening day Sept. 28. Previously, the purse was $200,000."The purse increase is being funded solely by Oak Tree, not by horsemen," said Sherwood C. Chillingworth, Oak Tree's executive vice president.The purse increase came after trainer Laura de Seroux announced on Monday that Horse of the Year Azeri would defend her title in the Lady's Secret. Chillingworth noted that the purse increase should encourage increased entries that otherwise would be reluctant to run against Azeri. "The top five finishers will all benefit from the purse increase," Chillingworth said.The Lady's Secret is one of four Breeders' Cup prep races that will be run on Oak Tree's Opening Day. Others are the $500,000 Yellow Ribbon Stakes (gr. IT), the $250,000 Oak Leaf Stakes (gr. II) and the $250,000 Clement L. Hirsch Memorial Turf Championship (gr. IT).Azeri, winner of 14 of 15 starts and 11 consecutive races, is the reigning champion of the $2 million Breeders' Cup Distaff (gr. I).