Thermal weed control on horizontal and vertical surfaces in archaeological sites as an alternative to herbicides

Flaming could be an alternative weed management at archaeological sites because it controls a wide range of weed species without inducting future resistance. The aim of this study was to test the weed control efficiency of flaming on various horizontal and vertical surfaces of archaeological buildings. Working times and costs were recorded. Flaming performances were compared to the normal herbicide treatments and mowing. Results showed that repeated flaming reduced weed cover by 100%. Working times and total costs decreased by increasing the number of applications over time. This is because the repeated flaming applications deplete the weed root stocks, thus keeping the mortar between the stones or bricks and the building materials free from weeds and their seeds for a long time. The method involved zero toxicity for humans and animals, thus providing safe accessibility to the archaeological buildings and visitor pathways. The application of flaming did not cause any damage or change of colour to the treated materials, although specific, multidisciplinary studies on this subject will have to be conducted in the next future, in order to exclude any negative effect on the remains. The results of these studies showed that flaming is a viable alternative for controlling weeds growing on archaeological surfaces.