Diseases and pests of plants of the Hydrangeaceae dumort. family in the Central Chernozem region of the Russian Federation

Beautiful flowering shrubs are widely used in landscape design of cities. In addition to the aesthetic impact, they have a broad-spectrum positive effect on all components of ecosystems: they saturate the air environment with biologically active substances, phytoncides, increase humidity, and absorb many toxic substances. Having a positive impact, the plants themselves will often experience stress from urban conditions. In recent years, the possibility of introducing rare species, distinguished by high decorative qualities and resistance to the negative impacts of urbanized ecosystems, into the range of flowering shrubs used in the floristic design of the territory, has become relevant. The object of our study was plants of the Hydrangeaceae Dumort family, growing in an urban environment. The research covered different areas of the Orel city: public areas; restricted areas; special purpose areas. Monitoring studies were carried out on the species composition and abundance of entomo- and phytopathogenic objects, and the vital state of plants was assessed. The following diseases were identified: white rot (Sclerotinia sclerotiorum), powdery mildew (Erysiphales spp.), rust (Puccinia spp.), septoria (Septoria spp.), gray rot (Botrytis cinerea). The highest infection of hydrangea plants with diseases was noted in the territory of special purpose: powdery mildew (17.3%), rust (10.1%), white rot (9.9%), gray rot (8.3%), septoria 7.7 % with development intensity of 6.3%, 3.3%, 4.9%, 1.9% and 1.5%, respectively. Hydrangea was damaged by Tetranychus urticae - 1.2 points (common areas), and 2.1 points (special purpose areas), Aphididae - 0.6 points in the general and restricted areas and 1.8 points - special purpose areas. The highest index of vitality was noted in plants grown in the restricted area (80%), the lowest one - in the common area (73%); weakened plants damaged by pests and diseases, with about 30% of damaged branches were found on the territory of special purpose. Their vital status index was 62%.