Efficacy of Beauveria Bassiana and Abamectin in the control of strawberry mite - Phytonemus pallidus (Banks) (Acari: Tarsonemidae) and the susceptibility of cultivars to pest infestation

BACKGROUND: The Strawberry is an economically important crop in Poland. However, the production of strawberries is difficult and costly, as pests and pathogens causing diseases often damage plants. The strawberry mite - Phytonemus pallidus (Banks) is the most dangerous among pests and one of the most difficult to control. In the past, active substances such as Endosulfan, Amitraz and Propargite, were used to control the pest but they have been withdrawn from the pest control program a few years ago. OBJECTIVE: The intention of this study was to evaluate the efficacy of Abamectin and fungus Beauveria bassiana to control the strawberry mite on strawberry plants in the open field, as well as the susceptibility of selected strawberry varieties and genotypes to the pest. METHODS CONTROL EXPERIMENTS: Studies were performed on ‘Honeoye’ plants. Naturalis (Beauveria basiana) at a dose of 1.0–1.5 l/ha+adjuvant Protector (pine resins) at a dose of 0.3 l/ha, Naturalis – 1.0 l/ha+TerraSorb^® Complex SB (α – amino acids, biostimulants) – 1.5 l/ha (2013) and Vertimec 018 EC (abamectin) at a dose of 1.0 l/ha were estimated. The population of strawberry mite was notated both before, and after the application of the tested products. SUSCEPTIBILITY OF CULTIVARS: The observations of the strawberry mite presence on the strawberry cultivars, were carried out in years 2012–2013 on an experimental cultivar trial plantation. The population of the pest was counted on strawberry leaves, taken from plants of different varieties and genotypes. RESULTS: Vertimec 018 EC showed good efficacy in the control of the strawberry mite, but the long-lasting effect was observed only following two applications of the product. Naturalis (Beauveria bassiana)+Protector proved to be more effective than the treatment of Naturalis+TerraSorb^® Complex, however the pest control was poorer and of short duration than after application of Vertimec 018 EC. CONCLUSIONS: In experiments carried out in the open field Abamectin proved to be more effective than Naturalis. Some strawberry varieties such as ‘Dukat’, ‘Flair’, ‘Real’, ‘Salut’, ‘Vima Rina’, ‘Malling Pearl’ were not infested by to strawberry mite - the pest specimens were not observed on experimental plots within two years of this experiment. A high population of the strawberry mite was noted on strawberry cultivars such as ‘Evita’, ‘Hokent’, ‘Albion’, ‘Feriusz’, ‘Honeoye’ and ‘Karel’.