Study of infectious diseases of ornamental plants of Asteraceae family in outdoor planting collections of the Donetsk Botanical Garden

Abstract

The need for regular phytopathological monitoring of collections in the Donetsk Botanical Garden is due to the risk of invasions of new plant pathogens on introduced ornamental plants under conditions phytopathogens in the 21st century, as well as the annual replenishment of the collections with new plant species, varieties, cultivars. A phytopathological examination ornamental plants collections of Asteraceae family was carried out in 2016-2019, according to which 15 genera, 19 species and 3 cultivated hybrids of plants showed various diseases caused by plant pathogenic organisms. Microfungi (30 species) predominates among the plant pathogens; plant damage caused by viral and bacterial diseases was also observed. The most common infectious diseases in the Donetsk Botanical Garden (DBG) were caused by powdery mildew fungi (recorded on 8 plant species) and rust fungi (on 5 plant species). There were found some new plant pathogenic microfungi in DBG, which were previously not recorded in the DBG and which can be treated as alien species to the region: powdery mildews of Symphyotrichum spp. (pathogen - Golovinomyces asterum ), Coreopsis spp. ( G. spadicaeus ) and Helianthus tuberosus ( G. latisporus ), rusts of Tanacetum balsamitae ( Puccinia balsamitae ) and Symphyotrichum spp. ( Coleosporium asterum ), and smut of Gaillaridia spp. ( Entyloma gaillardianum ). Various leaf spots were regularly noted in the collections, but they did not cause significant damage of Asteraceae plants in outdoor planting conditions. The most harmful types of diseases were wilting caused by Fusarium oxysporum and Verticillium albo-atrum , and rots of rhizomes and tubers of perennials such as chrysanthemums ( Chrysanthemum × hortorum ) and dahlias ( Dahlia × cultorum ) caused by Berkeleyomyces basicola , Ilyonectria destructans , Sclerotinia sclerotiorum and opportunistic pathogens Clonostachys rosea and Stachybotrys chartarum .