Comparison between standard and drift reducing nozzles for pesticide application in citrus: Part II. Effects on canopy spray distribution, control efficacy of Aonidiella aurantii (Maskell), beneficial parasitoids and pesticide residues on fruit

Venturi nozzles are often recommended to reduce drift, which is one of the major pollution sources caused by the application of plant protection products on high growing crops. The coarse droplets produced by this type of nozzle could however also affect the spray distribution and therefore the efficacy of pesticide treatments, the population of beneficial parasitoids and levels of residues on fruit. For these reasons, this work aimed at providing scientific evidence of any effect in these parameters when using standard (cone) or drift reducing (Venturi) nozzles for citrus foliar applications against California red scale (CRS) applied with conventional axial fan airblast sprayers. Results showed that Venturi nozzles did not affect efficacy in the conditions of the experiment. Moreover, in general terms, no differences were found in the distribution of the spray deposits over the tree canopy, on levels of residues on fruit or on the effects on the population of parasitoids. All these findings suggest that Venturi nozzles can be regarded as a good alternative to the standard cone nozzles for reducing drift of pesticide applications against CRS in citrus under Mediterranean conditions.