Alternatives to commercial airblast sprayer use in olive, PART 1: development of new sprayers specially designed to reduce the plant protection product losses

The new guidelines on pesticide application rationalization make necessary to adapt the applied doses to the real needs. Although farmers are getting increasingly aware of the pesticide risks and their use is controlled, the appropriate application of these products is key to prevent crops from suffering a high incidence of pests and diseases. As this circumstance contrasts with the low efficiency of the conventional airblast sprayer, the University of Cordoba (UCO), along with three machinery manufacturers and with the support of the Spanish Olive Oil Interprofessionals and the Spanish Ministry of Economy, Industry and Competitiveness, developed three new sprayers to reduce the product losses and to make the leaf surface coverage to increase. The sprayers were developed in two years by the companies that won the public tendering for accomplishing some technical requirements imposed by the UCO, whose basis was to reduce the product loss and to improve the efficiency. The three machines developed were: I) A sprayer with a centrifugal fan and six air spouts mounted on structures with independent movement to copy the canopy shape, II) A sprayer with six small-sized lateral fans with axial flow driven by hydraulic engines and mounted on lateral mobile structures, and III) A sprayer with double axial fan mounted on a tower-like structure with lateral mobile deflectors that funnel the airflow towards the tree crown with nozzles grouped in packs of three. Each sprayer accomplished the requirements imposed in a different way. After their reception, the prototypes were characterized and calibrated in laboratory conditions, where they were inspected according to RD 1702/2011, and their air flow rate for each PTO speed was determined. The mechanism of adaptation to the tree shape was also checked. The results of the laboratory tests were completely satisfactory and they allowed for the test of the sprayers in field conditions.