Some prospects of growing and use of china aster for space greening in Podillia zone

Annual aster, also called China aster (Callistepsus chinensis (L.) Nees) is one of the priority ornamental flower plants for the introduction both in Ukraine and throughout the world. Domestic and foreign scientists are diverse in the study of this plant. Most of the works published during the last decades are devoted to the study and search for the most favorable agrotechnical techniques for aster cultivation under different conditions. The research was being carried out during 2016‑2017 on the territory of the Bio-stationary of Vinnytsia National Agrarian University with partial subsequent data processing at Bila Tserkva National Agrarian University. The purpose of the study was to identify the most adapted and resistant samples among the collection cultivars of China aster for their further breeding and greening of various objects of Vinnytsia region. The methods of field and laboratory research were applied in accordance with the basic methodological requirements. The prospects of growing cultivars of China aster (Callistepsus chinensis) in the green space of Vinnytsia region were analyzed. The demand for new cultivars of different groups of annual aster in ornamental gardening and the need to develop decorative cultivars resistant to diseases and adapted to the environment was proved. For the first time, biomorphological features of Chinese asters (Callistepsus chinensis), methods of reproduction and the most promising cultivars for their growing under conditions of Vinnytsia region and their further use in landscaping of various objects were investigated. A collection of cultivars of different groups of Chinese aster on the territory of the collection site of Vinnytsia National Agrarian University was produced and unified. Due to high ornamental qualities, economic and biological qualities of the studied cultivars, all of them are evaluated as well adapted to the edaphic and climatic conditions of Podillya and they are recommended as objects intended for the replenishment of the assortment of plants for greening, collection and exhibition funds as well as breeding activities. A diversity of colours and forms of inflorescence, various shapes and height of the bush enable to use China aster widely in the single linear plantations, group plantations, for the arrangement of mixborders and plant beds, on the rocky landscapes and borders, to create groups and flower beds.

Occurrence of tomato spotted wilt tospovirus in native flora, weeds, and horticultural crops

Surveys to determine the incidence of tomato spotted wilt tospovirus (TSWV) in native plants, weeds, vegetables, and flowering ornamentals were done within or near horticultural properties in the Perth metropolitan area. Leaf or petal samples were tested for TSWV by enzyme-linked immunosorbent assay (ELISA). Samples from native plants and flowering ornamentals were also tested for impatiens necrotic spot tospovirus (INSV). Forty-two species of native plants were sampled from 17 sites. Of the 1590 plants sampled, only 1 plant of Calectasia cyanea (blue tinsel lily) was found to be infected. Weeds were sampled from 24 sites, and samples from 5543 plants in 45 species were tested. TSWV was found in 59 samples belonging to 16 different species from 8 sites. Among these, the highest virus infection levels at individual locations were in Arctotheca calendula (capeweed; 15%) and Sonchus asper (sowthistle; 32%). Vegetables were sampled from 28 sites, and samples from 3864 plants in 9 species were tested. TSWV was found in 309 samples from 22 sites. Those found to be infected were broad bean, capsicum, celery, chilli, eggplant, globe artichoke, lettuce, paprika, potato, and tomato. At individual locations, capsicum and tomato crops were sometimes 100% infected. Flowering ornamentals were sampled from 6 sites, and samples from 2698 plants in 16 species were tested. TSWV was found in 296 samples from 3 sites. Those found to be infected with TSWV were alstroemeria, calendula, Chinese aster, chrysanthemum, cosmos, dahlia, delphinium, gladiolus, snapdragon, statice, and zinnia. Highest incidences were in alstroemeria (32%), asters (81%), calendula (65%), chrysanthemum (30%), dahlia (28%), and statice (57%). No INSV was detected. In an infected calendula crop, TSWV infection declined sharply with distance from an aster infection source. Eight isolates of TSWV obtained from different weeds, vegetables, and flowering ornamentals differed widely in the severity of symptoms they induced in Nicotiana glutinosa, capsicum, and tomato. High incidences of TSWV were commonly associated with the presence of Frankliniella occidentalis (western flower thrips). Reservoirs of TSWV infection identified during the survey included infected planting stock and volunteer plants of vegetatively propagated flowering ornamentals, seedlings of vegetables previously infected in nurseries, old infected vegetable and flowering ornamental crops growing next to subsequently planted crops, and weeds. A control strategy involving the removal or avoidance of TSWV sources and vigilance to limit introduction of INSV on imported flowering ornamentals is discussed.