SensiSpray: site-specific precise dosing of pesticides by on-line sensing

In agriculture crop protection products (CPP) are used to protect the crop against pests, diseases and weeds. Several sprayings of CPP are done per crop per season. The used amount of CPP per spraying is generally based on a pre set CPP dose. Most often fields with variations in crop development are treated uniformly while spraying some patches in these fields would have been sufficient. In order to deal with the variations in crop development and site-specific variations in a field, a sensor-based spray technology was developed; SensiSpray. The system consists of sensors to detect crop variation and a spray system to automatically change spray volume. Electronics and software were developed to use the output signal of the sensor to adapt spray volume. For the variation of spray volume Lechler VarioSelect nozzle bodies were used fitted with four different low-drift venturi flat fan nozzles. On a 27 m working width boom sprayer seven sensors were placed on each boom section to control spray volume per boom section of 3-4.5m wide. Spray deposition measurements were performed to test the sprayer accuracy in adapting spray volume based on the reflection signal per section, using a fluorescent dye (Brilliant Sulpho Flavine) added to the spray liquid. The system is able to adapt spray volume within 1-2 m in the direction travelled. To demonstrate the potential use, the SensiSpray system was used in potato haulm killing spraying. The variation in reflection of the potato canopy was used to control the spray volume during desiccation spraying before harvest. MLHD PHK dosing algorithms for potato haulm killing herbicides were used to translate local greenness into a minimum effective dose. In the 2007 and 2008 season different potato fields were sprayed and a general use reduction in CPP for potato haulm killing was circa 50%, maintaining efficacy.