SEATTLE — The straws that are stirring the Yankees toward an AL East title for the first time in seven years are made out of maple and ash.

When the Yankees clinch the AL East next month, the biggest reason will be the home run for a team that has been without Giancarlo Stanton’s muscle for much of the season.

Wednesday at T-Mobile Park, the Yankees turned on the latest power surge when they slugged four homers on the way to a 7-3 victory over the hapless Mariners that was witnessed by 32,013.

The Yankees have hit 18 homers in the last six games and a major league record 70 in 28 August games. That doesn’t figure to stop because they have two more games in hitter-friendly Yankee Stadium before August fades away. Their 250 homers this season are the second most in franchise history to last year’s major league record of 267 and second in the big leagues.

“We still have a couple of games to complete the month,’’ Gary Sanchez said. “We go out there to give it all. Home runs come on their own.’’

Sanchez started the home run parade with a 434-foot blast that landed in the upper deck in left field in the first inning off former Yankees prospect Justus Sheffield. Sanchez knew the ballpark couldn’t hold his 30th blast, but wasn’t sure if it was fair or foul. Ruled fair, Sanchez started a slow jog around the bases.

Aaron Judge, who homered in six of the nine games on the West Coast trip that opened in Oakland with three losses, moved to L.A. (2-1) and ended with a three-game sweep of the Mariners, sent a 2-2 pitch from Sheffield over the left-field wall for his 18th homer that highlighted a four-run fifth inning and snapped a 2-2 tie. Judge finished 3-for-5 with two doubles.

Mike Ford continued his homer barrage with a solo shot off Sheffield in the fifth. It was Ford’s ninth homer of the season and fourth in four games. Finally, DJ LeMahieu reached the upper deck in left in the ninth for his 23rd homer.

James Paxton was the beneficiary and improved to 11-6 with his sixth straight victory. Paxton allowed two runs on Kyle Seager’s two-run homer in the fourth that tied the score, 2-2. He yielded one hit, walked five and struck out four in five innings.

It was Paxton’s first time facing his old team since being dealt to the Yankees last offseason for Sheffield.

In his second career start, Sheffield, who some believed was the Yankees’ top pitching prospect, gave up six runs and five hits in 4 ¹/₃ innings.

The win allowed the Yankees to bounce back from the sweep in Oakland and go home with a 5-4 record on the trip. It also pushed their AL East lead over the second-place Rays to a season-high 11 ½ lengths, pending the outcome of the Rays-Astros game Wednesday evening in Houston.

“They are very resilient and very hungry,’’ Aaron Boone said of his club. “Sometimes you have a series where they get you but from a mindset standpoint I have never had reason to be concerned with these guys and what they are going to bring for the next day and the next series. For us to take care of business [Wednesday] after a rough start to this trip and finish off a really good West Coast trip really says a lot about those guys out there.’’

Those are the same guys using maple and ash to stir lethal blasts that are the Yankees’ calling card on the way to the AL East championship.