ETOBICOKE, Ontario - Southdale, a leading contender for the June 21 Queen's Plate, came out of last weekend's Plate trial with an injury and is expected to be be sidelined for at least the balance of the summer.\nA thorough examination on Monday found the source of the problem.\n"He's hurt up in the shoulder," said Ian Black, who trains Southdale for owner/breeder Rod Ferguson.\n"We blocked [froze] him from the foot to the ankle to the knee, and we still couldn't get him to go sound. Assuming the shoulder is what it is, three months of stall rest usually fixes those things," said Black. "It's different if it's muscle but I don't think it is, to be honest with you."\nSouthdale, unstarted at 2, burst onto the Queen's Plate scene this spring, finishing third in his 6 1/2-furlong debut at Keeneland and then winning his maiden over seven furlongs here.\nDespite his lack of experience, his evident talent was enoughfor Southdale to be made the strong 2-1 favorite in the 1 1/8-mile Plate Trial, which he lost by just a neck to Eye of the Leopard after leading deep into the stretch.\n"I'm sorry for the owner, and everyone at the barn," said Black. "The Queen's Plate only comes around once a year."