Fullback Grayson Tihema had a strong first half, laying on the first of winger Elijah Ah Chong's two tries and scoring another himself with quick dashes and steps off both feet.
Wanganui's primary concern was Wairarapa-Bush's speedy little flanker turned winger Epeli Rayaqayaqa, who ran low and fast across the turf to score two smart individual tries while laying on his team's consolation five-pointer with time nearly up.
"Not bad, a bit of helter skelter," said Wanganui coach Denis Edwards.
"Once we settled it down a bit - that testostrone. The offloads were good."
Edwards also praised his inside backs and loose forwards.
Getting the better of early territory, Wanganui struck first as prop Wiremu Cottrell and first-five Josh Fifita had a crack at the line before the ball was freed to Campbell, who dragged two tacklers over the line.
A series of penalties with lineouts gave Wairarapa-Bush the chance to flip the momentum, and despite resolute tackling they eventually got through after Rayaqayaqa wrong-footed the defence and sprinted back through the players turning from being at the lineout to score in the corner.
Wanganui hit back immediately as Tihema fielded a clearance and stepped around the chasing forwards to find the gap - sending the pass to Robinson who put Ah Chong over in the corner.
Tihema scored right on halftime when he snapped up a loose Ratu pass and dashed between the last defenders to go under the posts.
The hosts had a bad start to the second stanza with a shallow kick being grabbed by Rayaqayaqa, who spotted the big gap beside the disengaging ruck and dashed through, wrong-footed Tihema and went under the posts for 17-12.
Wanganui were tested on their line but came up trumps in every one-on-one tackle and driving down attempts at rolling mauls, eventually breaking out as Sagapolutele showed great strength after going back to get a loose pass and then hold off his tacklers until he could unload to winger Karl Pascoe who sprinted into the corner and around to improve Tihema's kick.
Moments later, Tarogi fended his way through the line on his 40m and put the foot down to win the race to the corner to make them safe at 29-12.
Despite being reduced to 14 with 17 minutes left, Wanganui were now running hot as Tarogi picked up another bounce ball and spread to Ah Chong to get his double, while Robinson got free on the other sideline to dive over by the corner flag.
Throwing it around, the ball came to Sagapolutele in the gap off a Campbell pass to score, before Wairarapa-Bush got the final say as another Rayaqayaqa sycthing run was stopped just short and the ball was transferred out to first-five Pu'a Tafa at the corner.
Wanganui Development's next game will be against Horowhenua Kapiti Development in Levin this Saturday.
Wanganui Development 50 (Elijah Ah Chong 2, Jackson Campbell, Grayson Tihema, Karl Pascoe, Osea Tarogi, Cade Robinson, Eric Sagapolutele tries; Tihema 5 con) bt Wairarapa Bush Development 17 (Epeli Rayaqayaqa 2, Pu'a Tafa tries; Tristan Fluety con). HT: 17-5.
