BALTIMORE, JULY 31 -- Delmarva Downs will continue receiving simulcasts from Rosecroft Raceway after its meeting ends next month, General Manager Jim Murphy said today.

Cross-simulcasting between the harness tracks this summer has resulted in a 6 percent increase in handle over the Freestate and Delmarva meetings of 1989, Murphy said, sealing the decision to extend Rosecroft-to-Delmarva intertrack wagering through Dec. 22, the day Rosecrost closes. Delmarva finishes its meeting Sept. 9, after which it will have no races to send to Rosecroft.

Delmarva, located in Berlin, Md., near Ocean City, has Maryland Racing Commission approval to accept Rosecroft's races through the year. However, Delmarva executives are awaiting an interpretation of a law that would subject the track and its horsemen to additional withholdings if its average daily handle exceeds $166,000, which it has. At a racing commission meeting last month, Murphy questioned the intent of the law and said it could offset the advantages of cross-simulcasting. Nevertheless, the track is proceeding with its plans until the attorney general's office issues a clarification.

Rosecroft and Delmarva, both of which are owned by Mark Vogel, plan to seek a longer schedule for cross-simulcasting in 1990, Murphy said. Rosecroft also has had talks with Timonium Race Course officials about beaming races there.

Vogel, meanwhile, said he hopes to finalize his purchase of Atlantic City Race Course next week. . . .

Jockey Joe Rocco, sore from a spill on Sunday, did not ride this afternoon at Pimlico. It cost him the mount on Gronwohld, who won the $21,000 allowance feature, and sole possession of first place in the jockey standings. He, Mark Johnston and Edgar Prado have won nine races each. . . .

Trainer Alan Goldberg said that Safely Kept's next start probably will come in the $350,000 Frank De Francis Memorial Dash here on Aug. 18; Murphy, meanwhile, said Housebuster would be more likely to run in the $75,000-added King's Bishop Stakes at Belmont that day. Murphy bred Housebuster. . . .