Validation of SpraySafe Manager, an aerial herbicide application decision support system

SpraySafe Manager (SSM) is a computer-based aerial application model, which unlike previous models, has a simple user interface. SSM not only predicts spray deposition but also integrates this data with herbicide-plant dose-r esponse curves. This latter facility allows the operator to predict the siz e of buffer zone required to avoid damage to sensitive plants outside the s pray area and the degree of weed control within the spray block. Validation trials showed that, for a helicopter applied spray, the model tended to ov erpredict spray deposition on stainless steel plates close to the spray blo ck and underpredict deposition in the region 32-80 m from the centre of the spray release line and on isolated plants. The accuracy of model predictio n was greater when the spray was applied using D8-45 nozzles orientated at 90 degrees, than for spray applied using D6 nozzles orientated at 0 degrees . The reasons for this are discussed. The model can also be used to predict possible work rates, hectares sprayed per hour, and potentially as a train ing tool.