Thermal weed control
The principle of thermal weed control
The emerged parts of the weeds are destroyed by thermal shock. Indeed, raising the temperature of weed leaves to about 80°C causes the plant cells to rupture as a result of protein coagulation. The leaves lose their rigidity and rapidly dry out leading to the death or weakening of the plant.
Effect on the environment and soil life
The effect is limited to the emerged parts of the plants; the increase in the soil temperature is minor and therefore has no effect on the microflora and microfauna in the soil. The combustion gas does not pollute water or the soil. No sulphur dioxide (SO2), a major cause of acid rain, is produced.
How is this heat produced?
Most devices comprise burners fuelled by propane gas. These burners are used either with a “naked flame” in certain devices or to produce infra-red radiation in other types of equipment, combining the effect of infra-red radiation and the hot air flow produced by the burners.
Weed sensitivity to heat
Most annual weeds treated at an early stage are destroyed with one treatment. Perennials are not sufficiently weakened by a single heat treatment so the treatment must be repeated several times a year in order to weaken the plant by gradually depleting the root’s energy reserves.