Baldock missed the 2-0 win over Tranmere on Saturday with a recurrence of his ankle injury and is unlikely to recover in time to feature against the Pilgrims.
Defender Sean O`Hanlon is also out with an ankle injury and has been sent for a scan on the problem.
Utility man Jude Stirling is still to shake off a groin injury which has plagued his season.
On-loan QPR striker Angelo Balanta will be out of action until March with an ankle problem while fellow Rangers forward Rowan Vine will again be on the bench after joining the club last week.
Striker Jabo Ibehre will keep his place after scoring in the last two games as Karl Robinson's side look to move into the top five.