University of Guilan Plant Pest Research 2322-2409 15 1 2025 05 22 Effect of washing treatment on the efficiency of chemical control of olive psyllid in Tehran’s urban green space Effect of washing treatment on the efficiency of chemical control of olive psyllid in Tehran’s urban green space 17 30 8747 10.22124/iprj.2025.30006.1630 FA M. Rezaei Institute of Agriculture, Iranian Research Organization for Science and Technology (IROST), Tehran, Iran S. M. Mortazavi Tehran Municipality, Green Area Research, Education and Advisory Center, Area 20, Tehran, Iran 0009-0001-1553-6559 E. Mohaghari Sharabiani Tehran Municipality, Green Area Research, Education and Advisory Center, Area 20, Tehran, Iran M. A. Mirhosseini Department of Plant Protection, Faculty of Agriculture and Natural Resource, Persian Gulf University, Bushehr, Iran Journal Article 2025 03 02 The olive psyllid, <em>Euphyllura straminea</em> Loginova, is one of the most important insect pests of the olive trees in Tehran’s urban green spaces. Many chemical control programs for this pest have been unsuccessful. This study investigated how washing treatment affects the efficacy of common chemical pesticides used to control olive psyllid adults and nymphs in Tehran's urban green spaces. The trees underwent a washing process five days prior to the application of insecticides during the initial ten days of June. Following the washing treatment, the white waxy secretions produced by the pest were removed. The treatments consisted of 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. The number of individuals was recorded one day before and 3, 7, 14, and 21 days after spraying. The results indicated that pre-treatment tree-washing prior to the application of sprays markedly enhanced the efficacy of the interventions. In the context of nymphal control, the application of a washing treatment to trees resulted in an increase in percent efficiency of 22.10%, 30.48%, 33.43%, and 17.58% on the third day of sampling for the specified treatments, respectively. To attain effective management of the olive psyllid population while adhering to aesthetic standards in urban green spaces, it is advisable to wash the trees prior to the application of insecticides. This practice is intended to improve the efficacy of the chemical treatments and reduce the need for subsequent applications. The application of biocompatible insecticides that are safe for natural enemies is also advised. The olive psyllid, <em>Euphyllura straminea</em> Loginova, is one of the most important insect pests of the olive trees in Tehran’s urban green spaces. Many chemical control programs for this pest have been unsuccessful. This study investigated how washing treatment affects the efficacy of common chemical pesticides used to control olive psyllid adults and nymphs in Tehran's urban green spaces. The trees underwent a washing process five days prior to the application of insecticides during the initial ten days of June. Following the washing treatment, the white waxy secretions produced by the pest were removed. The treatments consisted of 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. The number of individuals was recorded one day before and 3, 7, 14, and 21 days after spraying. The results indicated that pre-treatment tree-washing prior to the application of sprays markedly enhanced the efficacy of the interventions. In the context of nymphal control, the application of a washing treatment to trees resulted in an increase in percent efficiency of 22.10%, 30.48%, 33.43%, and 17.58% on the third day of sampling for the specified treatments, respectively. To attain effective management of the olive psyllid population while adhering to aesthetic standards in urban green spaces, it is advisable to wash the trees prior to the application of insecticides. This practice is intended to improve the efficacy of the chemical treatments and reduce the need for subsequent applications. The application of biocompatible insecticides that are safe for natural enemies is also advised. https://iprj.guilan.ac.ir/article_8747_ffccfe02ee663181b9da8420516dbebe.pdf