EVALUATION OF AN ASSORTMENT OF ORNAMENTAL FORMS OF CONIFERS IN CENTRAL BOTANICAL GARDEN OF BELARUS NATIONAL ACADEMY OF SCIENCE

An extensive collection of ornamental conifers, including 210 taxa from 40 species, 10 genera, and 3 families, was evaluated for comparative analysis of seasonal development, shoot growth and resistance to environment factors, diseases and pests. Ornamental forms of species that have been tested for a long time and showed high resistance to climatic conditions in Belarus have been identified for further planting. At the same time success in growing some ornamental forms depends on timely prophylactic treatment for protection against pests and fungal diseases, especially for forms of Picea glauca (Moench) Voss. ‘Conica', which are susceptible to Oligonychus ununguis Jacobi. Ornamental forms of Thuja occidentalis L., Chamaecyparis pisifera Spach., Larix decidua Mill., Taxus baccata L. require permanent phytosanitary surveillance of needles for fungal pathogens and aphids.
Poecilophyllous forms of Juniperus L. have reduced resistance to local conditions. They have “coloured” shoots that dry in winter and spring periods. It is caused by low resistance of these shoots to increasing solar influence from the middle of February till the moment of snow melting and susceptibility to Phacidium infestans Karst. and Herpotrichia juniper (Duby) Petr.
The collection of ornamental forms is of great scientific and practical importance because of its diversity of taxa and forms suitable for landscaping. It serves as the basis for conducting scientific researches and selection of plants for landscape gardening. Prospects for further enrichment of the collection include obtaining ornamental forms of Abies Mill., Larix Mill., Tsuga L. and Pinus L. that are not in the collection of Central Botanical Garden or represented by only a few cultivars.