Herbicides always have a CF of 1
Table 1. A guide to theoretical (dilute) spray volumes for grapevine canopies.
From Radunz, L (2001) New label directions for spraying a review of experiences over the past year. Australian Grapegrower and Winemaker 451 pp45-46. (Reproduced with permission from The Australian Grapegrower and Winemaker).
Step 1. Theoretical (dilute) spray volume
Canopy size changes throughout the growing season. A range of theoretical (dilute) spray volumes are given for each canopy size. Choose the appropriate theoretical (dilute) spray volume from the above table. It must be within the recommended range.
For example, if the canopy is a 1m x 1m ‘sprawl’, the theoretical (dilute) spray volume could be:
650-1300 L/ha or 20-40 L/100m
The theoretical (dilute) spray volume you select will depend on the density of the canopy. For dense canopies choose a volume at the top end of the range.
Step 2. Actual spray volume
This is the volume of water your canopy spray unit has been calibrated to supply in either L/100m or L/ha. This figure will vary when you change your spray plant setup, i.e. Tractor speed, nozzle size, number of nozzles used.
Step 3. Concentration factor
Concentration factor (CF) = theoretical (dilute) spray volume actual spray volume
Example 1
Taking into account the canopy size and density, you decide that the theoretical (dilute) spray volume is 1700 L/ha. After calibrating the spray unit you find that the actual spray volume needed is 600L/ha.
Concentration factor (CF): = theoretical (dilute) spray volume actual spray volume
= 1700 ÷ 600
= 2.8
Example 2
Taking into account the canopy size and density, you decide that the theoretical (dilute) spray volume is 500L/ha. After calibrating the spray unit you find that the actual spray volume needed is 500L/ha.
Concentration factor (CF) = theoretical (dilute) spray volume actual spray volume
= 500 ÷ 500
= 1