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.
Water CEO apologises for contamination
22 cases of cryptosporidium have been confirmed in Brixham
South Devon water bug could last a week
Compensation of £15 offered
Devoncast - Mayoral mayhem, Bronze Age bounty and a river wrangle
The latest Devoncast podcast is out now
Duo charged over girls death at Exeter nightclub
A 16-year-old died after taking MDMA in Move
Radio Exe has largest-ever audience
Devon station continues to grow
Walkout, anger and tears mar Torbay mayor-making meeting
Tory group's U-turn leaves Mayor-elect stunned
