Reduced dosages (rates) are possible (especially in herbicides) if applied on the user’s own risk (declined liability of companies) and if resistance management criteria (especially fungicides) do not impose the full dosage.
The applied dose rate and water volume should be adapted to the area where the treatment is needed and its structure. In case of vertical crops such as pome fruit, the crop canopy area has to be considered, since it is recognized that the concentration dose expression – e.g. dose per hL or % – is no longer sufficient. To allow the three‐dimensional nature of the crop to be considered, the dose rate (on the label) should to expressed in e.g. kg or L per ha of Leaf Wall Area (LWA) or in kg or L per m3 of Tree Row Volume (TRV). The grower should have sufficient technical knowledge or external technical support to calculate/determine the LWA or TRV of the orchard(s) he/she wants to spray. The used water volume should also be adapted to the canopy area (for a full cover spray a runoff water volume is recommended). The exact concentration of the product (l or kg per l water used for spraying) is of secondary importance, as long as the required product per unit leaf wall area is deposited by the water over the full canopy. In exceptional cases the concentration (product dose rate/water volume) can be of primary importance, e.g. for treatment of a product with physical action (which depends on the concentration) or a spot application in an “Attract & Kill” strategy.