Nine appliances – six fire engines and three specialist units – were called to the fire, just south of Errol Airfield, shortly before noon on Monday.
A Scottish Fire and Rescue Service (SFRS) spokesman said a Skyhook helicopter, used for the likes of load lifting and firefighting, has been deployed to lift water from the River Tay and drop it on the flames.
Pictures shared on social media showed thick black smoke billowing up into the air, visible from as far away the Joppa end of the Portobello Promenade in Edinburgh – about 50 miles away as the crow flies.
The SFRS spokesman said firefighters were battling the flames using hose reel jets at different “sectors” of the fire, and that it now appears to be under control.
Local fire crews have been joined by an all terrain vehicle from Dunblane, a water carrier from Larbert and another support vehicle from Bo’ness.
There have been no reports of any properties being evacuated.
It is believed the spell of dry weather has created the conditions necessary for the fire to start naturally in the area.