Gunter played a one-two with striker Dexter Blackstock on the edge of the penalty area and swept the ball home into the bottom corner past goalkeeper Romain Larrieu after substitute Chester slipped while challenging him.
Sturrock, whose Pilgrims side stay bottom of the table after a seventh straight loss, said: "There's no way I can blame young Chester for the goal. I thought he did really well. I thought both Chester and Shane Lowry did well at the back for us.
"That's not the concern. The concern is that we need to score goals. I am sure that once we get goals, we will get a win.
"We are at Peterborough on Tuesday and have got Scunthorpe at home next Saturday.
"If we get six points from those two games, then we are in the pack above us again, so that has to be the target: six points."
Forest striker Blackstock skimmed a header just over from skipper Paul McKenna's fourth-minute free-kick.
Argyle countered with Alan Gow teeing up skipper Carl Fletcher, whose 20-yard shot on the run flew just wide after seven minutes.
In the 10th minute, Jamie Mackie sidefooted wide from six yards after Gary Sawyer's drive from the left was deflected into the path of Argyle forward.
Mackie went on a mazy run to make room for himself in the 25th minute and forced a save from Forest keeper Lee Camp.
Forest's impressive Radoslaw Majewski sent a dipping 32nd-minute shot on the run just over before Argyle were forced into a defensive shuffle when Iceland international Kari Arnason hobbled out with a hamstring pull.
Chances were few and far between in the second half, although Lowry made a goal-saving block to deny man of the match Majewski, who also went close with a shot.
Argyle's best two chances fell to substitute Alan Judge, who swept an 18-yard shot wide and then had a 25-yard shot on the run saved by Camp.
Forest assistant manager David Kelly said: "The performance was as good as we have been playing both at home and away from home but getting the three points was vital.
"We have been putting in the performances and not getting the results. Today we got the result.
"I felt we were in control for the majority of the game and the goal came at a good time for us.
"We were telling the midfielders to get forward and Chris has got forward and got the goal. It was well worked and he finished well.
"Radoslaw was brilliant on the ball. He has been out with a knee injury but desperate to get back.
"He's only had a couple of days training but showed what he was all about out there today. He has a superb work ethic."