اولین گزارش قارچها و نماتدهای مرتبط با عارضه زوال درختچه‌های پیراکانتا و روش های کنترل موثر در فضای سبز شهری

Scarlet firethorn (Pyracantha coccinea), a thorny evergreen shrub, is widely cultivated in urban green spaces. In this research, during the spring and summer of 2021, samples of scarlet firethorn shrub displaying symptoms of chlorosis, dieback and decline were collected from the parks located at 17th district of Tehran Municipality. For the isolation and identification of pathogenic fungi, pieces of infected tissues (Root, crown, stem) after washing with water and surface sterilization with 1% sodium hypochlorite solution were placed on different agar media with alternating 12 hours light and 12 hours darkness at 25 ± 1 °C. Purification of fungal colonies was performed using single spore and hyphal tip methods on 2% water agar medium. The fungal isolates were identified based on morphological characteristics and valid identification keys. To confirm species identification, molecular identification based on the ITS-rDNA and partial β-tubulin gene sequences was conducted. In general, from fungal isolates recovered, two isolate belonged to Fusarium oxysporum and one isolate belonged to Phytophthora ramorum. In order to identify nematodes, a number of rhizosphere samples were collected and transferred to the laboratory. The nematodes were extracted by sieving and centrifugation method, then fixed with glycerin, and permanent microscopic slides were prepared. The morphological and morphometric properties were examined using a light microscope equipped with a drawing tube. Species were identified using valid keys. In the initial study, several populations of two species of lesion nematodes (Pratylencus coccinea and P. thornei) and one population of larvae of Ditylenchus were identified. The pathogenicity of the isolated agents was confirmed on one-year-old scarlet firethorn shrubs under greenhouse conditions. The control of these pathogenic agents was carried out in three pilot locations from a geographical point of view. The experimental treatments included sulfur fertilizer with a purity of 80%, a new combination of Nemakoub Plus (Vegetable acetic acid), and periodic application of sulfur and Nemakoub Plus in a period of fourteen days in two times. The results of this research showed that sulfur inhibited the pathogenic agents by 78% and Nemakoub Plus by 83.50%, and periodic treatment of sulfur fertilizer and Nemakoub Plus completely inhibited pathogenic agents. Based on the obtained results, periodic use of sulfur and Nemakoub Plus can be recommended as a suitable alternative to chemical fungicides and nematicides while maintaining a healthy urban environment in controlling scarlet firethorn diseases.