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Effects of Autumn Treatments on the Rosy Apple Aphid’s Colonies in SpringAlins, G.1, Alegre, S.1, Avilla, J.2 The rosy apple aphid (Dysaphis plantaginea Pass.) is one of the most important apple pests in Spain that seriously damage shoots and fruits. Furthermore, the strategies to control this pest are not completely satisfactory on organic fruit production. In order to give an additional method to control this aphid, an experiment was conducted in autumn of 2004 in an IRTA-Estació 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 and a control treatment) were applied 3 times in a complete randomize block design with 8 replicates. The first application (18th October 2004) was performed when winged aphids were observed on the apple trees. Every treatment, except defoliation, was repeated on 3rd and 12th November 2004. The rosy apple aphid was monitored on 10 shoots per tree in autumn and on 10 flower buds per tree in spring. Results show that only pyrethrin extract and defoliation were able to significantly reduce autumn recolonization and spring colonies. The rest of the treatments tended to reduce the presence of this aphid but no significant differences were observed from the control treatment, maybe because they were applied too late. To improve the timing of application of each product several trials will be conducted in 2006.
1 Institut de Recerca i Tecnologia Agroalimentàries (IRTA), IRTA-Estació Experimental de Lleida. 2 Àrea de la Protecció de Conreus, Centre UdL-IRTA, Spain
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