Development of machines for flaming weed control on hard surfaces

Weed control is a major issue not only in agriculture but also on hard surfaces in urban and suburban contexts. Weeds can cause serious damage to urban structures and are often considered as a sign of neglect. Moreover, citizens are becoming increasingly aware of environmental pollution and its potential risks for their health. Flaming represents a concrete alternative to herbicide applications on hard urban surfaces. Flaming can also be a good alternative to mechanical means (e.g., string trimmers) which can seriously damage surfaces because they are too intense and in any case are often not effective. The aim of this work is to describe LPG fed flaming machines designed and built at the University of Pisa, Italy. Liquefied Petroleum Gas (LPG) is a flammable mixture of hydrocarbon gases– propane and butane. Four different machines were developed and tested in four different urban and sub-urban contexts. A small backpack flamer equipped with a manual lance was tested on a stonewall, a trolley machine with a manual lance was used to clean the base of ornamental trees, a self-propelled machine was tested in a railway station, and a mounted machine was used in a suburban cycle way. Flaming was compared to the ordinary weed control systems such as using herbicides or mowing. The results showed that flaming can be both less expensive and more effective (on average less that 1 € m-2 year-1 maintaining weed cover below 5% to 6%) than the ordinary treatments in urban areas. Flaming was more effective than mowing in the suburban area but much more expensive, thus an integrated approach would be advisable in this context. Future research should be devoted to improving the efficiency of the treatment, using for example, new burners with secondary air and precision agriculture technologies.