Patch spraying system requirements

The use of a patch spraying system based on a treatment map requires ... 

Methods by which dose and mixtures of spray chemicals can be delivered at different controlled rates have been discussed earlier in this section. For spatially variable (patch) applications, Miller et al. (1997) summarised the performance requirements of the application system as follows ... 

An important feature of using these manual sprayers is that it is possible to do selective spot treatments, for example, confining the application of herbicides to patches of weeds. Also, where there is concern about downwind spray drift, placement of the nozzle nearer to the target and using a low pressure can enable treatments closer to a sensitive area. In conjunction with an attractant such as molasses or protein hydrolysate, insecticide bait sprays have been used in discrete spots for fruitfly control. Knapsack sprayers are often used in difficult terrain where access to vehicles is difficult or impossible. However, the lack of water in some situations, and the high requirement for labour, have created a demand for alternative application systems (see below). 

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