Max Scherzer won his fifth consecutive start, taking a shutout into the seventh inning.
The Nationals jumped on Pirates starter Chad Kuhl (3-2) for solo home runs by Wilmer Difo, his first of the season, and Adams in the third and fourth innings, respectively, to take a 2-0 lead before exploding in the fifth and sixth.
Harper provided the big blow of the fifth, his ninth home run, extending the Washington lead to 5-0.
One out later, Adams completed his the sixth two-homer game with his sixth of the season, another solo shot that gave Scherzer a six-run cushion.
The Nationals broke the game wide open with a six-run sixth, with Turner producing half of the runs with his three-run double.
Adams, who hadn't had a two-homer game since last June, added a third RBI with a two-out single.
Scherzer (6-1) lost his shutout in the seventh when he walked Josh Bell and got taken deep by Corey Dickerson for a two-run homer, his fourth of the season.
Scherzer was pulled after 6 1/3 innings, having allowed two runs and three hits. He walked two and struck out eight.
Kuhl went 4 2/3 innings, allowing six runs (four earned) and four hits. He walked two and struck out three.
Adams, Harper and Turner finished with three RBIs apiece for the Nationals, who supported Scherzer with 15 runs in his last start, a 15-2 win at San Francisco.
Adams, who had three hits, and Difo, who had two, scored three times apiece, helping Washington win for the third time in five games on their 10-game homestand.
Max Moroff completed the scoring for Pittsburgh with a two-run homer, his first of the season, for the Pirates in the ninth.
Bell and Colin Moran had two hits apiece for the Pirates, who have begun a nine-game trip with consecutive losses.
The Nationals out-hit the Pirates 10-8.
--Field Level Media
Pittsburgh | Washington | |
Chad Kuhl | Player | Max Scherzer |
Loss | W/L | Win |
4.2 | IP | 6.1 |
3 | Strikeouts | 8 |
4 | Hits | 3 |
7.71 | ERA | 2.84 |
Pittsburgh | Washington | |
Josh Bell | Player | Matt Adams |
2 | Hits | 3 |
0 | RBI | 3 |
0 | HR | 2 |
3 | TB | 9 |
.667 | Avg | .750 |
Team | Hits | HR | TB | Avg | LOB | K | RBI | BB | SB | Errors |
Pittsburgh | 8 | 2 | 18 | .229 | 11 | 11 | 4 | 3 | 0 | 2 |
Washington | 10 | 4 | 23 | .286 | 8 | 6 | 12 | 4 | 1 | 0 |