Biological efficacy evaluation of low-drift nozzles compared to classic hollow cone nozzles for chemical control of key pests Cacopsylla pyri (pear sucker) and Eriosoma lanigerum (woolly apple aphid) in apple and pear

Abstract: Over the last decade, the reduction of the emission of plant protection products to the environment has become an important issue in pip fruit growing. One elegant solution to limit spray drift to a minimum is the use of low-drift nozzles. Air-induction nozzles generate large drops filled with air bubbles which explode into fine droplets in contact with the plant. However, information regarding the efficacy of these drift reducing nozzles compared to classic hollow cone nozzles in spray applications for the control of insects pests in pip fruit orchards is scarce. The objective of this study was to examine the biological efficacy of different spraying techniques, in particular different nozzle types, in controlling key pests Eriosoma lanigerum (Haus.) and Cacopsylla pyri (L.) in apple and pear orchards, respectively. Field trials were set up in apple and pear orchards in a fully randomized block design, with the untreated control included and in a homogenous pest presence. Insect pests were sprayed with registered plantprotection compounds applied with different spraying techniques in the different trial object. This way four spraying variables were tested: two different sprayer types (axial fan and cross-flow sprayer) and two different nozzle types (air-induction and classic hollow cone nozzles). Assessments of the presence of the insect pests were executed according to international standards, following the appropriate EPPO guidelines. Regardless of some biological variation peculiar to field trial studies no significant differences in biological control efficacy of E. lanigerum and C. pyri were obtained for the different nozzle types used in this study. For both, systemic as well as contact insecticides, the low-drift nozzles performed equally to the classic hollow cone nozzles. The low-drift nozzles even tend to have a better control of C. pyri in the top part of the trees, especially when a contact insecticide was treated with the axial fan spraying equipment. Our results show that air-induction hollow cone nozzles are as effective as classic hollow cone nozzles for spraying crop protection compounds against E. lanigerum and C. pyri in apple and pear orchards, respectively. Hence, the use of this more environmentally friendly spraying technique can go hand-in-hand with excellent control of these key pests.