Comparison of Intensity of Infestation of Gossyparia spuria (Modeer) on Elm Trees in Various Microclimates of Isfahan

European elm scale [Gossyparia spuria (Modeer)] is one of the most important pests of elm trees inIsfahan province (Behdad,1987). In this study, intensity of infestation of elm trees in various regionsof Isfahan city was studied. Samples were collected biweekly from Ulmus carpinifolia and Ulmuscarpinifolia var. umbraculifera which are the most common trees in the Isfahan landscape. In fivegeographical zones of the city (North, South, East, West and Center), percentage of infestation andintensity of infestation was determined. 85.6% of U. carpinifolia and 72.6% of U. carpinifolia var.umbraculifera were infested. Low infestation intensity, [mean number of 0.6-2 female scales on 16branches (each 30 cm long)] and medium infestation intensity (mean number of 2-20 female scales on16 branches) were observed on U. carpinifolia and U. carpinifolia var. umbraculifera ,respectively.Results showed that infestation of elm trees in humid microclimates in the city center and adjacent tothe Zayandehrood river is much more pronounced than in other parts of the city.