Hawke's Bay did make them work defensively, especially after halfback Sam Nock was sent to the sin bin following an intentional foul at a ruck just out from the Northland line.
The Magpies took toll of the numbers advantage as a grubber from first five Ihaia West sat up for winger Cardiff Vaega to allow them to tie things up.
First five Peter Breen added three points to the lead after missing his first two shots of the 2017 season.
The game descended into a midfield struggle for the next ten minutes as both sides were guilty of throwing away opportunities to score.
But Northland showed they were the more clinical side as another good lineout set up a strong driving maul. Pryor held the ball at the back before the weight of it became too much for Hawke's Bay to handle, giving the openside flanker his second for the afternoon.
Breen slotted the extra two, handing Northland a 10-point buffer at the break.
Northland came out from the break desperate for a much needed try scoring bonus point but they were matched by an equally hungry Magpies outfit looking for just their second win of a disappointing campaign.
The Taniwha held off an attacking raid and went on one of their own, started by hooker and captain Matt Moulds.
Moulds fended off a would be defender and charged into open space on a 30-metre run before finding Ranger on his inside for the try.
Hawke's Bay looked to have come back into the contest in the 70th minute, only for Vaega to be denied by the TMO.
Northland went back on the hunt for the bonus point and replacement flanker Kara Pryor forced another Hawke's Bay turnover inside their own 22.
Michael Faleafa took the ball into contact before finding hard-working lock Tim Bond for the crucial fourth try.
With a win in the final round, where they play the runaway Championship leaders, Wellington, they will make the semifinals. However they could advance even with a loss, depending on how other matches unfold.
Northland 34 (Dan Pryor 2, Tim Bond, Rene Ranger tries; Peter Breen 2 con, pen, Dan Hawkins con, pen)
Hawke's Bay 7 (Cardiff Vaega try; Ihaia West con)
HT: 17-7