Recent years have shown enthusiastic research interest to reduce pollution of non-target such as sensitive environmental areas, human and non-targeted crops. In this way, the most important issue is that intermittent spraying on the trees simply needs a detection system to apply the spray only to the target trees, allowing the sprayer to turn off between trees or in areas where trees are missing. So, in this study, we present a low-cost sensing system that can apply a variable amount of liquid according to detection of the tree canopy for plant protection products applications in orchards. Target detecting system was implemented on a 2000 liter conventional towed air-blast orchard sprayer. In this study, the target detecting system was designed on the basis of “sensor-equipped spraying’. Generally, the optical sensors were used to detect the tree canopy, then send signal to PLC until which solenoid ON/OFF valves is opened. Laboratory and field experiments were conducted to evaluate its performance. During laboratory experiments, delay time to start and stop spraying, spatial lag were investigated. During field experiments, evaluation of water sensitive paper and evaluation of pesticide consumption were studied. In the laboratory test, forward speed did not show any significant effect on delay times of starting or stopping the spraying. Variance analysis of data of sprayed area on water sensitive paper (WSP) indicated that the effects of forward speed, vertical and horizontal place of water sensitive papers on the area of WSPs covered by sprayed liquid were significant at the 1% of probability level. The results of measuring the amount of sprayed liquid at studied forward speed levels showed about 50% saving in pesticide consumption implementing variable rate in comparison with the conventional spraying.

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