EFFECTS OF AUTUMN TREATMENTS ON ROSY APPLE APHID COLONIES IN SPRING

The rosy apple aphid (Dysaphis plantaginea Pass.) is one of the most important apple (Malus domestica Borkh.) pests in Spain. Furthermore, the strategies to control its populations are not completely satisfactory on organic fruit production. In order to develop an additional control method, an experiment was conducted in the autumn of 2004 in an IRTA-Estación Experimental de Lleida apple orchard located in Borges Blanques (Spain). With the objective of reducing rosy apple aphid populations in autumn and spring, different treatments (pyrethrin extract, potassium soap, garlic extract, kaolin, defoliation) were applied 3 times in a complete randomized block design with 8 replicates. The first application (October, 18^th) was performed when winged aphids were observed on the apple trees. Every treatment, except defoliation, was repeated on November 3^rd and 12^th. Only pyrethrin extract and defoliation were able to reduce significantly autumn recolonization and the number of occupied flower buds next spring. The other treatments tended to reduce the presence of this aphid but no significant differences were observed compared to the control. Several trials will be conducted in 2005 and 2006 to investigate the timing of application of each product.