WITHIN-TREE DISTRIBUTION OF SPIDER-MITES (ACARI, TETRANYCHIDAE) IN SPRAYED APPLE-TREES OF ORCHARDS IN BUENOS-AIRES PROVINCE, ARGENTINA

The distribution of Tetranychid mite populations within three varietie s of apple trees, and their preferences for the infestation of certain kinds of leaves were analyzed, in a chemically-treated commercial app le orchard, with terrestrial flood irrigation. The tetranychids do not present marked preferences for certain kinds of leaves in spring, but they preferably infest middle-sized leaves in summer. In this tempera te climate apple orchard, the phytophages have an homogeneous distribu tion within-trees, in spite of variety, architecture and age of trees. There are no microclimatic ranges or favorable sections for the devel opment of tetranychid mites, so sampling by random selection of leaves from any section of a tree could be carried out.