Three apple tree varieties of a sprayed apple orchard from SE Buenos Aires Province (Argentina) were studied, in order to compare their infestation by Panonychus ulmi. European Red Mite abundances and prevalences were calculated monthly, and ANOVA results showed that these parameters were almost always higher in Spur Red Delicious trees than in Red Delicious and Granny Smith trees. The differences in the way the trees are pruned, the external morphology of leaves and their hairiness could be the reasons for a differential infestation of P. ulmi in the varieties studied.