Reuveny H., Oppenheim D.,Kedoshim R., Berkeley M., Akunis O. - Northern R&D, Qiryat Shemona 11016

The pear psylla Cacopsylla bidens (Sulc) is a key pest in Israel pear orchards. The main damage inflicted by psylla is a fruit rusting caused by honeydew produced while feeding and sooty mold. The females lay eggs in the winter on fruit buds. Egg hatch begins close to the green tip (GT) stage of the trees. Before GT, oil with pesticides is applied to control the pest, and during the season treatment is mainly with amitraz and abamectin. Three to five treatments during the season are required. The intensive use of these pesticides has led to concern regarding resistance development and to calls for environmentally friendly alternatives. This study tested the efficiency of the particle film of inert alumino silicate mineral (kaolin, 'Surround WP') on pear psylla. This particle film creates a physical barrier between the pest and the plant. In laboratory experiments on young pear trees, kaolin was effective both for prevention and treatment against psylla. When used in pear orchards before GT, a significant reduction in the psylla enabled a delay in applying the spring treatments. In summer, kaolin treatments were inefficient against psylla. It seems that, since kaolin is not a pesticide, its film prevents new egg laying. However, the outburst of shoot growth between applications provides uncovered surfaces that are readily attacked by the pest and are enough to support population growth. This problem may be reduced by restraining vegetative growth. (P)