When Steven Schumacher made the decision to move to Stoke City at the midway point of the campaign, the Pilgrims hierarchy were forced into finding an alternative.
Having made an impression with England Under-18s, Under-19s and Under-20s, Foster was chosen to try to ensure that the club remained in the Championship.
At the beginning of the 47-year-old's reign, it appeared that the correct appointment had been made, Foster collecting seven points from his opening three matches in charge.
Since that initial form, though, Plymouth have won just once in 11 matches, that victory coming away at Middlesbrough back on February 24.
Plymouth woes
On Easter Monday, Plymouth succumbed to their fifth consecutive defeat at Home Park without scoring a goal, the first time that has occurred in their history, as they went down 1-0 to Bristol City.
That made it just one point and two goals from six matches, subsequently leaving Plymouth sitting just one point above the Championship relegation zone.
Although Plymouth sit just six points adrift of 15th position, the club's hierarchy announced on Monday night that they had chosen to sack Foster, replacing him with director of football Neil Dewsnip on an interim basis.
Chairman Simon Hallett said: "Ian was hired through a thorough and extensive recruitment process and his coaching credentials really stood out when making the appointment.
"But we have to balance long-term stability against short-term decisions, and we have given Ian as long as possible to see if results could improve.
"Unfortunately, that hasn't been the case, and we feel now is the right time to make a change to give us the best chance of securing survival."
Foster leaves Plymouth after just 17 matches in charge since his arrival at Home Park at the turn of the year, recording four wins, four draws and nine defeats.
Plymouth are next in action when they square off against bottom-placed Rotherham United on Friday night.