Tranmere boosted their play-off hopes with a win that leaves Hereford close to an instant return to League Two.
While the win moves Tranmere into the top six, Hereford now lie 12 points from safety with just four games left.
Ian Moore set Bas Savage through to open the scoring for Tranmere, before Charlie Barnett made it 2-0 from range.
Ian Goodison saw red for a lunge before Steve Guinan scored from the spot after Ryan Shotton had fouled Jennison Myrie-Williams, but the hosts held on.
Hereford United manager Graham Turner told BBC Hereford & Worcester:
"It's a very sad day but I wouldn't have swapped the experience of playing at this level.
"I said after the Leicester game that we could have been in the top seven or eight in the second division and it would have been a fairly happy camp.
"It's probably not the time to go into detail - that might be done over the next seven days - but there is just a huge depression about the place after everything that happened last season."
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