Greater Anglia has said no trains from Norwich can reach London Liverpool Street because of the obstruction, leading to cancellations or early terminations.
The tree, which fell yesterday, caused extensive damage to overhead electrical wires.
All services on the Intercity route between London Liverpool Street and Norwich will operate only between Norwich and Ipswich.
An extremely limited shuttle service will run between Ipswich and Colchester today, and passengers are advised not to travel between these stations.
The disruption is set to cause a major headache for Norwich City fans, who are travelling to Charlton for today’s EFL Championship match.