Sudden Occurrence and Harmfulness of Xyleborus dispar (Fabricius) on Pear

Decline of pear trees in the region of Čačak (Serbia) is becoming a significant problem and a limiting factor in the production of this fruit species. This phenomenon may be due to the damages caused by xilophagous insects, representatives of the family Scolytidae. Economically the most important species of this family is a pear blight beetle (Xyleborus dispar), which causes symptoms of decline and/or wilting of pear trees. Such damages have not been documented so far in the region of Čačak. The aim of this study was to determine the cause of sudden appearance of pear trees decline in an orchard in this region (locality of Miokovci). The orchard has 180 trees (Stark Delicious, Santa Maria and Williams) in the sixth year of vegetation. Inspections were carried out every 30 days (20 April - 21 August 2016). Visual inspection identified X. dispar activity on 165 trees (about 92% of the trees in the orchard). Holes were registered on the trees up to a height of 160 cm and in all primary branches. The average number of entry openings on a random sample of 20 trees was 27 for the height from the soil surface to the first branch (70 cm), while it was 61 for the height up to 160 cm. The recommended treatment is eradication of pests with mandatory incineration (burning) of the collected plant material by the end of February of the following growing season. This is the first report of X. dispar as pear pests in the vicinity of Čačak.