Control of summer fruit tortrix (Leafrollers) (BIOFRUITNET Practice Abstract)

Summary in the original language of the document

Pheromone disruption, eventually in combination with Bt-products (Bacillus thuringiensis) or Capex, are important to reduce fruit damage by leafroller larvae and thereby increase the saleable yield and storability of the fruits.
Practical recommendations
• Look at the level of damage on harvested fruit from the previous season to estimate the potential damage (Picture 3).
• Establish 800-1000 Isomate dispensers/ha as high in the orchard as possible. The high location is important for an optimal distribution of the pheromones by the wind in the orchard, and thereby optimises the effect of the treatment.
• The optimal distribution of the dispensers in the orchard are evenly in a square pattern of 3.5 x 3.5 meters over the entire treated area.
• In the outermost twenty meters of the orchard, the distribution of pheromones is especially affected by the wind. Therefore, it is necessary to conduct an edge treatment by hanging one dispenser in each end tree in each row, as well as to double the number of dispensers in the outermost rows.
• When treating areas that are smaller than 3-4 ha, there is a considerable risk of the infestation from mated females from untreated neighbouring areas.
• If the initial infestation with summer fruit tortrix is high, use additional application of Capex in spring.
• Monitor the occurrence of the leafroller species in spring. If you find relevant species that are not covered by the pheromone disruption Isomate CLR, such as Hedya nubiferana and Spilonota ocellana, apply Bacillus thuringiensis.