Use of Trans-Anethole Against Hop Flea Beetles in Field Conditions

In the present study, the effect of two different formulations (NCH1 and NCH2) of trans-anethole was examined against hop flea beetles, Psylliodes attenuatus in field conditions. Products were applied in different locations in the spring seasons of 2019–2021. In 2019, 0.5% and 1% concentrations of both formulations were used so that the effective field dose could be determined. Doses of 1% for both formulations were shown to be more efficient. In 2020, experiments with this dose were carried out in two localities in order to select a more suitable formulation of the product (NCH1 vs. NCH2). The NCH1 formulation was shown to be more effective. After application, there was a significant reduction in the number of flea beetles compared to the control (p < 0.0001). On the other hand, no significant difference was found between the non-treated plot and the NCH2 formulation. In the third year of the experiment (2021), it was found that the number of P. attenuatus on plants treated with NCH1 encapsulation was significantly lower than in the untreated control (p < 0.0001). Residues of trans-anethole degraded immediately; thus, the product is suitable for use in the summer to protect the hop cones before harvest.