The trees are concentrated around the village of Bickleigh, which has been found to be a high risk area for ash dieback.
The council has offered to carry out work on behalf of private landowners where required, to mitigate their responsibility and minimise disruption - "but they will need to bear their share of the cost", it said.
Devon County Council has so far dealt with 22 roadside trees infected with ash dieback.
Cabinet member for highway management Councillor Stuart Hughes said: "The County Council is taking a carefully managed, proactive approach towards dealing with this issue.
"Public safety on the highway has to be the priority and we are balancing that with environmental considerations."
Councillor Margaret Squires added: "We would urge all private landowners to take responsibility to ensure the safety of others by inspecting the condition of the canopy cover of their own trees when they are in leaf."
The council, which established the Devon Ash Dieback Resilience Forum two years ago, will resume its own tree inspections in spring.
Any trees found to be in an imminently dangerous condition are to be removed within 24 hours.