Adaptation of doses

OPTIDOSE : an IFV decision support tool  

• Development of decision rules by the IFV to modulate the doses of downy mildew and powdery mildew fungicides according to:
  • the phenological stage,
  • the actual surface of the plant to be protected,
  • parasite pressure, estimated by the risk forecasting models used by the IFV.
• Choice of products and rate not imposed.
• Recommendations: equipment properly adjusted, preferably face by face (see back of the sheet)

>>>> Decision rules to contextualize in each region

• Induced effects :
  • Test result with the OptidoseenGironde approach:
    • average reduction of 40% phyto
    • limited impact on the effectiveness of phytosanitary protection: average loss of effectiveness of 8% on the foliage and 3% on the harvest

In what conditions ?

Adjustment of doses:

• on the leaf surface
• at the rate of treatment (dose splitting)
• to parasite pressure
• adaptation of spray sections

Adaptation to the actual planting area

• assess the area actually planted (headlands, embankments, etc.)
• avoid border rows treated twice and spraying outside the plots, which implies consultation between neighbors or better management of spray sections.

Adaptation to the phenological stage (leaf surface)
Take into account the technical limitations of spraying devices:

• at the start of the season (until the beginning of flowering): confined spraying: recovery panels limiting losses by confining the spraying and recovering the mixture.
  Very efficient but cumbersome and difficult to use in narrow, sloping and slow vineyards.
• During the growth phase of the vine, localized spraying to target the spraying on the vegetation:
  Depending on the equipment, cut off the power supply to the nozzles or diffusers which are not directed towards the vegetation, modify the orientation of the diffusers 

Equipment adjustment: essential prerequisite for dose adjustment

1. Volume à l’ha :  Q = D x 600/V x L 

D: total flow (L / minute); Q: volume applied per ha (L / ha); L: treatment width (m) = number of rows treated x width between rows; V: forward speed (km / h)

To calculate D: total flow (L / minute)
Fill the circuit and the tanks to the brim
Switch on the sprayer for 2 min
Determine the amount of water that has run off over 2 min by refilling the tanks:
D = quantity of water supplied (L) / 2 min

2. Forward speed : less than 5.5 km / h

• On a straight line, install 2 markers 100m apart.
• Set the engine speed to the mark
• Start before the 1st mark to be at the right speed when passing in front of it.
• Start the stopwatch when the front wheel passes the 1st mark.
• Stop the stopwatch when the wheel passes the 2nd mark.
  Speed ​​(km / h) = 360 / nb of seconds for 100 m

3. Adjustment of nozzles or diffusers :

• type de buses,
• number of open nozzles (or outlets),
• tilt (up and down),
• orientation (angle with respect to the perpendicular to the row of
  vine)

4. PTO control : quality of spraying: use a tachometer to ensure the reliability of the tractor display and, if necessary, readjust it (locate the value on the tractor display which corresponds to 540tr / min measured at the tachometer)

5. Spray distribution : water-sensitive papers which take on a coloration on contact with the sprayed droplets.
Staple the papers on several layers of vegetation; on both sides of the row, on both sides of the leaves and in the grape area.

Maintenance and control: sprayer but also nozzles, diffusers, filters