Plant surfaces, spray target

The loss of pesticides due to volatilisation should not be underestimated. It has been estimated that much more pesticide is lost from its target by volatilisation than from spray drift (Anon., 1996). The pesticide formulator tends to encounter this problem when working with some soil-applied pesticides, or where a leaf deposit needs to remain on the plant surface. Pesticides taken up by foliage do not tend to suffer from this problem, as plant uptake mechanisms usually ensure that pesticide soon ceases to be available to this loss mechanism. 

The capture and retention of the spray droplets is often reduced to addressing the retention of spray droplets on leaf surfaces. This means that the direct loss of spray droplets to the soil surface is forgotten. Figure 7.2 shows how the density of the target foliage plays an important role in determining the proportion of the pesticide captured by the target plants. 

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