Thermal weeder
The principle of thermal weedkilling is to destroy the aerial part of plants by means of a thermal shock. The temperature of the leaf is raised to 70°C, causing the leaf proteins to coagulate and be destroyed. The action of thermal weeding can be likened to the application of a contact herbicide; only the parts affected and sufficiently heated are destroyed. Intervention at the seedling stage ensures good efficacy. The number of passes can be high, especially if the aim is to achieve very clean soil.
Live flame thermal weeding machine
Work objective
These are the oldest types of equipment, using gas combustion (often propane) to generate the flame that will be directed at the leaves. Gas consumption varies according to burner performance. Their limit of use is in dry conditions, where there is a real risk of fire. Forward speed is 2 to 3 km/h. Jaulent offers a range of multi-purpose equipment for weeding, removing shoots or leaves, using the same burner but positioned differently.Components of the live flame thermal weeder
Thermal flame weeders come in a range of complex designs.The chassis
One or more burners are fixed to the mechanically welded chassis. This is also used to transport the gas cylinders.
The burners
There are 2 types of burner:
- a coil that allows the gas to pass from a liquid state to a gaseous state. This is a complex burner that produces an unstable flame
- a torch flame burner, which produces a more stable flame. The burner is protected by a more or less complex bell depending on its design.
Thermal weeder burners
The protective bell
The protective bell concentrates the flow of heat towards the ground, thus avoiding any risk of burning the stock as a result of rising heat.The removal system
JAULENT offers a parallelogram-mounted system, with multiple settings for weeding, de-budding and leaf thinning. In the weed-killing version, the bell is mounted on a free axis, so the crop is removed from in front of the stock by bypassing it. This makes it possible to work as close to the stock as possible without the risk of snagging.Adjusting and using the live flame thermal weeder
Settings
The settings for this tool depend on the development of the weeds. The forward speed and operating pressure must therefore be adjusted according to the amount of plant cover. The working width depends on the equipment(around 40 to 50 cm).Use
When using a thermal weeding machine with a live flame, care must be taken toavoid the risk of fire (avoid working in strong winds, during periods of drought, etc).To obtain satisfactory results, it is best to intervene at the start of the weed's vegetative cycle (seedling stage). Progress speed is generally low and gas consumption varies according to the amount of plant cover.
Hourly gas consumption varies from 10 to 14 kg depending on operating pressure.
Hot water thermal weeder
Work objective
Hydro-France (manufacturer of high-pressure cleaners) has developed a range of hot-water weed-killers. This equipment, powered by the tractor's PTO or hydraulics, sprays water heated to 135°C at a pressure of 15 bar. According to the manufacturer, the water sprayed onto weeds has a foliar and root action.Components of the hot water thermal weeder
Hot water thermal weed-killers were initially developed by Hydrofrance.The alternator
The alternator supplies the electrical power required by the machine's various components. It is driven by the tractor's power take-off or a hydraulic motor.The high-pressure pump
This increases the pressure of the hot water delivery circuit. The pressure is around 20 bars.The hot water production unit
This is simply a large boiler. It is generally fuelled by fuel oil and heats water to a temperature of 135°C.The application system
This application system can be compared to a chemical weeding boom. It is made up of a water supply hose, a nozzle to distribute the water over the plants and retractable fairings to protect against water splashing or feet catching.Adjusting and using the hot water thermal weeder
Settings
The work rate is variable, depending mainly on the amount of plant cover, and the forward speed and working pressure must be adjusted accordingly. The water flow rate is 18 l/min and the forward speed 1.5 km/h.Use
Spraying hot water causes the cells to burst and the proteins to denature (blackening of the herbaceous parts), stopping the activity of the aerial part.For information, water and fuel consumption are, respectively, 3 m³ and 25 L/ha, for weed control in vines with an inter-row spacing of 2 metres.