Matching spray volume to crop canopy sizes and shapes can reduce the use of plant protection products , thus reducing operational costs and environmental pollution. Developments on crop adapted spraying for fungal control are highlighted in arable crop spraying. A plant-specific variable volume precision sprayer, guided by foliage shape and volume (canopy density sprayer ; CDS ) was developed for bed-grown crops to apply fungicides . Sensor selection to quantify crop canopy and spray techniques to apply variable dose rates are evaluated based on laboratory measurements. Based on the laboratory experience a prototype CDS sprayer was built using either a Weed-IT ® or a GreenSeeker ® sensor to detect plant place (fluorescence) or size (reflectance). Variable rate application was either done with a pulse width modulation nozzle or a switchable four-nozzle body. Spray volume could be changed from 50 to 550 l ha−1 in 16 steps. Spray deposition , biological efficacy and agrochemical use reduction were evaluated in a flower bulb and a potato crop during field measurements using a prototype CDS sprayer. Spray volume savings of a prototype plant-specific sprayer are shown to be more than 75% in early late blight ( Phytophthora infestans ) control spraying in potatoes . In flower bulbs (lily ) it was shown that in Botrytis blight control on average spray volume could be reduced by 45%. In a potato crop biological efficacy was maintained at the same good level as of a conventional spraying. In a flower bulb crop biological efficacy of the CDS was lower than of conventional spraying, which means that spray strategy and dose algorithms need further research.
van de Zande, J., Achten, V. T. J. M., Schepers, H. T. A. M., van der Lans, A. M., Kempenaar, C., Michielsen, J. G. P., ... van Velde, P. (2010). Precision disease control in bed-grown crops. In Precision Crop Protection - the Challenge and Use of Heterogeneity, Part 5 (pp. 403-415). Springer Science + Business Media. https://doi.org/10.1007/978-90-481-9277-9_25