Chemical suckering machine
Chemical suckering works by spraying a contact weedkiller on the shoots. For optimum effectiveness, it should be applied when the shoots are still tender (not lignified) and, if possible, no longer than 20 cm. The amount of spray to be applied per hectare should be in excess of 200 litres.
Depending on the grape variety, two applications will be required during the season.
Depending on the grape variety, two applications will be required during the season.
Components of the chemical suckering machine
The mast
Chemical de-budding involves spraying in a vertical plane. The equipment is often mounted on a gantry that spans the row, so as to remove the shoots from both sides of the vine simultaneously, while limiting the amount of spray. The mast provides the link between the gantry and the tractor. Fitted with hydraulic jacks, it can be adjusted for height, alignment with the row and, in some cases, tilt.The suckering head
This is made up of 2 sections, each fitted with 2 adjustable jets, to ensure correct wetting of the shoots. Some manufacturers offer tunnels equipped with 6 nozzles.Various safety systems allow the tunnel to retract in the event of a collision :
- a deformable parallelogram at the headers (Dhugues)
- a return spring on the frame uprights (Magneto)
- or simply a pin linking the frame to the mast to ensure self-centring of the head (S 21).
Flexible tarps positioned vertically and horizontal brushes limit spray :
- Dhugues offers to fit its de-budding tunnels with drip trays.
- The manufacturer claims (in favourable conditions) a recovery rate of around 25%.
- Avidor Higtech has developed detection equipment.
- This saves on product and speeds up work.
- Finally, Enviromist undavina (H 300) offers ultra-low-volume chemical de-budding equipment. The volume of spray applied per kilometre is around 5 litres (for a forward speed of 4 km/h).
Adjustment and use of the chemical suckering machine
Like all spraying equipment, there are a number of stages involved in setting up a chemical de-budding tunnel.
Determining the theoretical flow rate of the chemical suckering machine (D)
This is calculated using the following formula: D = (Q x L x V)/600
- The desired volume per hectare (Q) must be between 400 and 500 litres in order to properly wet the vine shoots while limiting run-off.
- The working width (W) corresponds to the height of the trunk on a flat surface.
- The forward speed (V) should be between 3 and 4 km/h. This is to ensure the right amount of work is done while avoiding rebound phenomena.
Note that the theoretical volume (D) calculated corresponds to one section (one side). To find out the total flow rate of the spraying boom, this value must be multiplied by 2 (since a spraying head comprises 2 sections).
Determining the flow rate per nozzle (d)
To correctly choose the nozzle/pressure combination, you need to know the theoretical flow rate per nozzle (d). This is calculated by dividing the total flow rate of the chemical spraying boom (D) by the number of nozzles, generally 4 (some equipment can be fitted with 6 nozzles).Choice of nozzle/pressure combination
This is made easier by the use of charts supplied by the nozzle manufacturers. These documents give nozzle flow rates (L/min) as a function of operating pressure.To limit the risk of spray mist, nozzles should be used that deliver the desired flow rate (d) at low pressure, which should be around 2 bar.
Still with a view to limiting spray mist, the spray angle will generally be 80°. Nozzles with 60° angles will be of interest when working on plots with a fairly low trunk height.