Whelpdale opened the scoring at Bristol Rovers after three minutes and Burton wrapped up the three points with the second a minute before half-time.
Second-placed Port Vale kept up the pressure on Gillingham with a 4-0 win over 10-man Plymouth. In the week Plymouth sacked manager Carl Fletcher the visitors went down to a Tom Pope brace and goals from Jenson Myrie-Williams and Ben Williamson.
Myrie-Williams opened the scoring after 32 minutes and Plymouth forward Luke Chadwick was sent off for violent conduct two minutes later. Pope netted his first after 55 before further strikes from Williamson (77) and Pope (83) sealed an empathic win for Vale.
Wimbledon moved off the bottom and out of the relegation zone with a 1-0 win away to 10-man Rochdale. Paul McCallum gave Wimbledon the lead after 56 minutes and the home side had Joe Rafferty dismissed three minutes later for a second booking.
Barnet eased their own relegation fears with a 2-0 win over Bradford with the defeat dropping the visitors out of the play-off places, while Exeter climbed into the play-off places as they moved up to fifth with a 2-1 win at York.
Northampton moved to within a point of the play-offs with a 3-1 win against Fleetwood. The win also moved Northampton within a point of the visitors who dropped to seventh as a result of the defeat.
Jake Robinson (7 and 41) and Clive Platt (53) put Northampton in charge before Jamie Allen (90) netted a consolation for Fleetwood.
Chesterfield saw their play-off hopes dented with a 2-1 defeat at improving Wycombe. James O'Shea gave Chesterfield the lead just before the half hour but Kortney Hause levelled on the stroke of half-time and Jo Kuffour (54) netted the winner for Wycombe.
Matthew Saunders (21) and Luke Howell (52) scored for Dagenham & Redbridge who won 2-0 away to Accrington.