Royal Roberto, one of Illinois' most successful stallions, died in July of a heart attack. The 25-year-old stallion was buried at Richard Duchossois' Hill 'N Dale Farm near Barrington, Ill., with his halter, blanket, and stall card, as is the farm tradition.Duchossois bought Royal Roberto from the dispersal of the late Col. Mitchell Wolfson in 1983. The price, $2.2 million, established a record for a horse in training at public auction.For Duchossois, Royal Roberto won two allowance races, but failed to place in four stakes. He was retired to stud for the 1984 breeding season with a record of nine wins from 27 starts and earnings of $331,648. For Wolfson, who bred and raced Royal Roberto in the name of Key West Stable, the son of Roberto had won four stakes, including a division of the Lexington Stakes (gr. IIT) at Belmont Park. He was New York-bred champion 3-year-old male.Royal Roberto, whose first season at stud was $12,500, sired 16 stakes winners, the same number of stakes-placed runners, and the earners of $8.4 million. Two sons, Ambivilent Force and Markus' Powereplay, topped the $350,000 mark, and a daughter, Sea Girl, was a two-time champion in Argentina.Royal Roberto, who was produced from the Royal Note mare Princess Roycraft, ranks No. 3 by lifetime progeny earnings among Illinois stallions.