DETROIT — General Motors Co. will end its half-century run as sponsor of the Buick Open golf tournament as it tries to focus scarce marketing dollars on its cars and trucks, a person briefed on the decision said Tuesday.

GM and tour officials will make the announcement after this year's open, which begins Thursday and ends Sunday, said the person, who did not want to be identified because the announcement will not be made until the tournament ends.

The decision calls into question the fate of the other PGA Tour stop sponsored by GM, the Buick Invitational held in February in San Diego.

GM spokesman Pete Ternes said the company is discussing its future role with PGA Tour officials. The company's contract for the Open and the Invitational ends in 2010, he said.

"Both are under discussion and we haven't signed or agreed to any changes at this point," he said Tuesday.