Trueman, 22, has been dogged by a persistent issue in his back since last year and it has been decided he now requires an operation.
The Great Britain tourist has not played for Castleford since scoring in the Challenge Cup final loss to St Helens at Wembley last month - his only game since the semi-final victory over Warrington Wolves on June 5.
Powell said: “It’s been really difficult for Jake, and he sadly won’t play again this year which for us is obviously disappointing.
"He is a high-quality player and we wish him all the best with the surgery and recovery."
Castleford visit champions Saints in Super League tomorrow hoping to get a first win there since 1992.
Props Liam Watts and George Griffin should be back in the squad after recovering from Covid.