Walton is missing with a knee injury that he sustained in the second half of Monday's 3-1 defeat to Southampton, which relegated the Pilgrims, however the problem is thought not to be as serious as the knee problem that sidelined him for most of this season.
Striker Rory Fallon is a doubt as he is struggling with a cold and will be assessed late on.
Young Irish forward Joe Mason could make the starting line-up after appearing off the bench in the last two matches.
Reid went with an attacking line-up against the Saints with Yala Bolasie, Kari Arnason and Rory Patterson urged to get forward and support Fallon and it remains to be seen whether he goes with the same system or brings Luke Summerfield back into midfield.
Source: PA
Source: PA