Terry Baker, a 26-year-old vocational education teacher from Hagerstown, burst through the final three-quarters of a mile yesterday to upset four-time defending champion Bill Rodgers in the 10-mile Perrier Cherry Blossom Race.

Rodgers, who has won the New York and Boston marathons four times each, was unable to match Baker's end-of-the-race stamina and finished seven seconds behind. Baker was timed in 49:29.

A 30-mile-an-hour head wind slowed the runners at the end of the race--the three-mile stretch from the tip of Hains Point to the finish near the Lincoln Memorial--and Baker's time was more than two minutes off the course record of 47:09 set by Rodgers in 1980.

Eleanor Simonsick, 23, of Washington, a policy research consultant, was the first woman to finish, in 58:16. Marge Rosasco, 33, of Fallston, Md., was second in 58:30 and Cynthia Lorenzoni, 23, of Charlottesville, first among the women in last year's Marine Corps Marathon, was third in 58:52.

In the men's field, Dan Gruber, 26, of Scotts Valley, Calif., was third in 49:41; Matt Wilson, 23, of Fairfax was fourth in 49:58 and Mark Donahue, 21, of Charleston, S.C., was fifth in 50:13.

Baker, winner of the 1981 Virginia Beach Marathon and the Charleston (W.Va.) 15-Miler, ran evenly with Rodgers until about a quarter-mile past the nine-mile mark.

"I wanted to make a move at that point, so I made a hard surge, and that seemed to be the difference," he said.

Rodgers, 34, who failed last year to win either the Boston or New York marathons, was disheartened by his second-place finish.

"You try to get a good time for Boston (the April 19 marathon)," he said, "and then you have a 30-mile-an-hour wind that slows you down by two minutes. It's discouraging."

Toward the end of the race, Rodgers said, "I kept trying to break away but I couldn't break away. Terry was too strong, and he finally broke away, and I couldn't catch him."

Gruber, a cross-country coach at a California community college who bruised two ribs playing basketball last week, contested Baker and Rodgers for the lead until about the nine-mile mark. "Then they just ran away from me," he said.

In the women's field, Simonsick and Rosasco, who finished second and third in last month's Avon 20-kilometer race at Hains Point, also ran evenly until just past the nine-mile marker.

At that point, Simonsick said, she sprinted to catch up with a group of men just ahead of her, hoping to use them to break the head wind blowing down the Potomac.

"Marge just didn't keep up with me then," she said.

Lorenzoni, running just behind Simonsick and Rosasco for most of the race, said the wind was so powerful in the final stages that "it was hard to keep my feet moving."

The course looped the Tidal Basin once and East Potomac Park twice before returning to the finish on Ohio Drive.

As the runners broke from the starting line, about 10 contestants vied for the lead, which changed hands several times as they rounded the Tidal Basin, the Japanese cherry trees in blossom. With the wind mostly at their backs, the leaders recorded their best times in the early stages of the race, finishing the first mile in 4:46 and the first two in 9:32.

At the four-mile mark, the time was 18:57. But the pace slowed as the runners rounded the tip of Hains Point for the run back up the channel side of East Potomac Park. It took 5:03 to complete the fifth mile and 5:17 to finish the sixth, and the pack at the head of the race grew smaller as the leaders took turns breaking the wind for the others.