Abstract: A spectral detection system discriminating the targetsfor the non target area was tested during sprayapplications in apple and pear orchards. The objectiveof the test was to evaluate the accuracy of the systemworking at different application parameters and toestimate the rate of possible spray savings obtainedduring applications on the trees of different size andweeds of different density. The system consisted of thespray units equipped with optic sensor and a controlunit which could operate up to 16 spray units. Eachspray unit had an optic detector and two light sourcesemitting two beams of light at the wavelengths 670 and750. The ratio between emitted and reflected light foreach wavelength was the basis for discriminatingbetween the presence or the absence of chlorophyll. Theinformation was processed and used to control theelectric solenoid valves opening or shutting off thenozzles. The target detection system worked technicallyproperly. It enabled the selective spray applicationwith spray savings adequate to the tree row profile. Inintensive apple and pear orchards 16-25 percentreduction of spray volume was obtained. For herbicideapplications the detection system discriminated weedsfor the bare ground. Both sensitivity of the sensorsand weed density had a significant influence on thespray savings. At medium sensitivity, a considerablespray saving amounting 23 percent was obtained only onthe plots with very low weed coverage. !9
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