بررسی اثر آبشویی درختان بر کارایی کنترل شیمیایی آفت پسیل زیتون در فضای سبز شهری تهران

The olive tree is one of the important plant species in the urban green space, which is considered due to its evergreen nature and relative resistance to cold, drought, and salinity. In recent years, the olive psyllid, Euphyllura straminea Loginova (Hemiptera:Liviidae), has become one of the most important problems of the olive trees in Tehran’s urban green space. The olive psyllid has several generations in the urban green spaces. Along with sucking plant sap, the insect produces abundant white waxy secretions, which has made it difficult to control the pest population, especially by spraying insecticides. Therefore, this research investigated the effect of washing trees on the efficiency of some common chemical insecticides to control this species in the urban green space of District 20 of Tehran Municipality (Janbazan Park). The trees were washed five days before spraying insecticides in the first decade of June so that the white waxy secretions of the pest were no longer visible. The treatments include chlorpyrifos (EC 40.8%) 2000 ppm + emulsifiable oil (L 80%) 3000 ppm, acetamiprid (SP 20%) 500 ppm + emulsifiable oil (L 80%) 3000 ppm, malathion (EC 57%) 2000 ppm + emulsifiable oil (L 80%) 3000 ppm, emulsifiable oil (L 80%) 3000 ppm, and control (water). The number of E. straminea was recorded one day before and 3, 7, 14, and 21 days after spraying. The samples were taken to the laboratory and counting of the alive nymphal stage was done. The Henderson-Tilton equation was used to calculate the percentage efficiency of insecticides. According to the results, the percent efficiency on 3, 7, 14, and 21 days after spraying was estimated as 63.83, 54.42, 39.97, and 23.22% without washing and 85.93, 76.46, 58.48, and 42.18% with washing for chlorpyrifos + emulsifiable oil, 64.19, 59.85, 36.91, and 29.17% without washing and 94.67, 91.04, 79.17, and 53.78% with washing for acetamiprid + emulsifiable oil, 56.85, 54.07, 43.45, and 26.27% without washing and 90.29, 82.80, 73.23, and 44.42% with washing for malathion + emulsifiable oil, and 18.50, 12.95, 6.32, and 2.85% without washing and 36.08, 20.42, 11.01, and 7.67% with washing for emulsifiable oil, respectively. The percent efficiency of all treatments, except acetamiprid + emulsifiable oil on 21 days after spraying and emulsifiable oil on 7, 14, and 21 days after spraying, showed a significant difference between washing and no-washing tress before spraying. It is recommended to control the olive psyllid population considering the beauty threshold in the urban green space, before spraying the pesticide, the trees should be washed to increase the efficiency of the pesticide and prevent repeated chemical control.