Technological aspects of Steinernema carpocapsae spray application alone or mixed with Bacillus thuringiensis aizawai in spinach crop

Foliar application of entomopathogenic nematodes (EPN) is generally carried out with traditional boom sprayers. However there is a possibility that this operation may cause physical stress to nematodes due to the action of the mechanical components. Our aim was to evaluate the effects of a spray application, with a conventional hydraulic sprayer, on the viability of Steinernema car-pocapsae (Weiser) in spinach crop. Laboratory tests preceded foliar application in the field to exclude possible effects on the ne-matodes due to the spray equipment. In a field trial, applications of EPN alone and in a mixture with Bacillus thuringiensis Berliner (Bt) subsp. aizawai were carried out evaluating their level of control against noctuid moths in spinach. The biopesticides action was also compared with conventional chemical control. In addition, the interaction from the combination of Bt and EPN was investigated. Results showed that a static pressure up to 14 bar causes no significant damage to S. carpocapsae and that the passage of the nematode through the flat fan nozzles do not affect their viability. Repeated recirculation of nematodes by hydro-ejector did not affect their viability even at high recirculation level (36.9 l/min). In the field trial, treatment with EPN alone and with the mixture EPN+Bt showed no significant differences with respect to the control. Nevertheless, in general these treatments were not significantly different from chemical treatment. The combined application of EPN and Bt showed an additive interaction compared to EPN alone.