Integrated Control of Scales on Highbush Blueberry in Poland

In the past decade, the development of highbush blueberry production in Poland has been followed by the occurrence of new pests in the plantations, including scales. Since both the assessment of the populations of natural enemies present in a territory and the knowledge of the scale species present in the crop are crucial for the correct application of IPM strategies, a study was carried out to address these aspects and evaluate the efficacy of several active substances in controlling <i>Parthenolecanium</i> spp. in several highbush blueberry plantations. Specimens of adult larvae collected on several plantations were phylogenetically closely linked to two species, <i>P. corni</i> and <i>P. fletcheri</i>. However, considering the ecology and behavior of these species, it was concluded that the pest population was more likely to belong to <i>P. corni</i>. Analyzing the scale parasitoids’ community present in the different locations, it emerged that it was quite diversified, including species affecting both the initial and adult biological phases of the scales, with differences also in the population size and diversity, including both general or specialized parasitoids and predators. The different active substances tested in the efficacy trials, which included both synthetic and bio-based compounds, were suitable for controlling the scale infestation. However, the different efficacy observed between them, depending on season and location, could be interpreted taking into consideration the initial level of infestation. It is concluded that applying an IPM strategy that combines agronomical practices with the application of insecticides with different mechanisms of action, attentive to the benefit of protecting natural enemies, can result in satisfactory control of <i>P. corni</i> in highbush blueberry plantations.