The first half was low on quality but the hosts did create two gilt-edged chances with simple balls unlocking the Southam defence, only to waste them both.
Saints’ disjointed efforts were not helped by first-half injuries to Myles Jones and Andy Yeates which required substitutions.
Southam strung together their best move of the game six minutes into the second period. Louis Bridges and Tunde Ajibade combined well and a stretching James Hardie was inches away from turning the resulting cross into the net.
Four minutes later, two unforced errors allowed Stuart Hall to open the scoring.
First, keeper Tom Cross mis-kicked his clearance and then Adam Guest failed to clear the loose ball, only turning it into Hall’s path, who rolled the ball into an unguarded net.
Pershore doubled their lead in the 69th minute with Joe Walsh allowed to amble into the Saints penalty area untracked and meet a mishit centre to shoot past Cross.
Southam’s only other effort of note came in the 77th minute when Chris Bright’s powerful shot slid wide of the far post.
Things went from bad to worse for the visitors in added time as Kevin Spencer was shown a straight red for a two-footed challenge.
Southam entertain fellow mid-table side Stafford Town tomorrow (3pm).