"He came without being paid which shows what type of lad he is.
"He played a huge part in our success last season and the goal will be remembered for decades - not only in terms of his importance but the type of goal it was and the time in the game."
Igoe made 94 appearances in just over two years as a Rovers player, scoring six goals.
The 32-year-old spent the last part of the current season on loan at Hereford United, helping them achieve promotion from League Two.
Chris Carruthers signed for Rovers initially on loan from Northampton in March 2005, and scored one goal in 128 appearances for the club.
"Chris has played a big part, he's been frustrated recently that he's had a lack of first-team opportunities," said Trollope.
"Again, he played a big part in our success last year. His involvement was great in what we achieved so we'd like to thank him for his efforts and wish him well for the future.
"I'm sure he'll get a league club and do well for himself."
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