Speaking in the Scottish Parliament, Gray said the wildfire that burned in the Cairngorms, near Aviemore, for almost five weeks was one of 58 incidents in Scotland this year.
It broke out near Glenmore and burned across about 10 sq miles (25 sq km) of moorland and forestry.
Some homes and campsites had to be evacuated, and at the height of the incident more than 500 firefighters were involved in the response.
The Cairngorms National Park Authority said two specialist helicopters were “invaluable” for waterbombing hard-to-reach areas.
Work continues in the area to monitor for hotspots.
Grey said rescue services in England and Wales responded to 342 wildfires in the first six months of this year.