The fires have been on farmland in areas around Newton Abbot, Teignmouth, Paignton and Dawlish.
All the incidents involved a number of fire crews attending the scenes for long periods of time.
Safety advice has now been issued to farmers on how to reduce the risk of arson, including preventing easy access and installing security.
North Devon house fire treated as arson
One person still missing
Cornwall charity is sending aid to hurricane victims
Teams help with devastation
Huge tuna caught off Devon breaks record
What a wopper!
Devon and Cornwall Police gets another bad report
Three out of three areas 'require improvement'
Fears for future of Torquay's custody centre
MP warns top cop about review
Will Barnstaple remain a port?
Boatowners weigh in on decisions
