Aster

Family Asteraceae. Name: 'Aster' - the Latin transcription of the Greek 'asteros' - star; the name was given for the shape of the inflorescences.

"ASTRA" - in practical floriculture under this name there are two genera: aster (Aster L.) and callistephus (Callistephus Cass.) with one species (C. chinensis (L.) Nees), or Chinese callistephus, or the annual aster, widely cultivated.

Planting conditions: asters are fairly undemanding plants, but give the greatest decorative effect when conditions similar to those of their wild relatives are created. General rules are as follows. They can be grown in semi-shaded places, but for asters that flower in autumn well-lit, sunny sites are preferable so that they have time to bloom. In addition, with less light there is a high risk of powdery mildew. They are not overly demanding of soils, but prefer cultivated, fairly fertile loams dug to at least 20 cm. Light soils must be watered regularly. Poor soils should be amended with organic matter before planting at the rate of 10 kg of humus per 1 sq. m; on light soils add 20 g of nitrogen mineral fertilizer. Asters prefer well-drained, permeable soils. Wet sites that are waterlogged in spring and autumn are unsuitable.

Asters that bloom in autumn are better planted and divided in spring (when they begin to regrow), then they will flower the same year. When planted in autumn they often do not have time to root before the permanent freezing of the root layer of soil and die. Plants are planted at distances of 20-40 cm from each other so that young underground shoots are covered with a 2-3 cm layer of soil. After planting, water; if the plants become exposed, add more soil. Fertilize starting from the second year after planting.

Care: asters respond well to applications of phosphate fertilizers and lime. In dry periods they need regular watering, especially during bud formation. With insufficient water and nutrition leaves turn yellow prematurely and the number of inflorescences decreases. Overall they are drought-tolerant, but the New-Belgian types require moister soils, and the New-English types prefer more fertile ones. During the growing season feedings are traditionally given in two terms - in spring at shoot emergence: nitrogen 6 g, potassium and phosphorus 4 g per sq. m; at the bud stage potassium and phosphorus 5 g each; and one application in autumn with a complete mineral fertilizer. When grown in the same place for a long time, New-English and Italian asters need periodic organic feeding, which can be done as mulch with humus. They can grow in one place for 5-6 years, but it is better to divide and transplant every 3-4 years.

Propagation: by seed and vegetatively. Seed propagation is used rarely, when necessary, because seed viability is lost quickly; sow immediately after collection for winter in the open ground or in cold frames, in extreme cases in spring at a depth of 0.5 cm. Seedlings with 2-3 true leaves are pricked out, and the following spring planted to their permanent place. Seedlings bloom in the 1st-2nd year after sowing.

In practice vegetative propagation is used more often. Division of the clump is done in early spring when asters start to regrow, removing all weak stems. Asters can also be propagated without digging up the clump. Using a sharp spade, one or several parts are separated and these can be further cut into smaller divisions. A standard division should have 3-5 new shoots, though others consider one bud and several roots sufficient. The planting scheme depends on vigor in the adult state and can range from 20x30 to 50x80 cm. Cultivar asters are also propagated by cuttings, which can be taken from May-June until August. Use apical cuttings 5-7 cm long for this purpose. Cuttings are planted in specially prepared beds with a loose substrate (turf soil with peat and sand added in a 2:1:1 ratio) in a shaded place, preferably under film. They root in 25-30 days. You can also take shoots for cuttings in spring and early summer that have reached 15 cm, remove them from the clump and cut into pieces 2 internodes long (each should have 3 leaves). In this case they can be planted out in late August - early September.

Diseases and pests: powdery mildew, ring spot, yellows (viral), grey rot of flowers, spittlebug froth, spider mite, leaf and gall nematodes.

1) In autumn asters are often affected by true powdery mildew, as a result of which the leaves and stems of plants are covered with a grayish-white bloom. The causal agent is the fungus Oidium. Varieties of asters of the New-Belgian type and a. heath-type are more susceptible to this disease; New-English types are less affected. Susceptibility to powdery mildew is increased by lack of nutrients in the soil, insufficient watering, overcrowded plantings, and the "advanced" age of plants. To keep asters healthy in the garden, select resistant varieties, fertilize well, and rejuvenate and transplant plants in time. Control measures include colloidal sulfur (Sulfarid) or Topaz.

2) Ring spot is a dangerous fungal disease in which dark concentric rings formed by fungal spores appear on the leaves. Infected leaves should be removed and burned; treat plants with Polychom, Bordeaux mixture, or Fundazol every 2 weeks.

3) Yellows is a viral disease. Infected plants must be destroyed immediately. There are no control measures.

4) Gray rot is also a fungal disease caused by Botrytis. Flowers become covered with a grayish-white bloom. During the bud stage and again a month later plants should be prophylactically treated with copper-containing preparations - copper sulfate, Bordeaux mixture or copper oxychloride. Severely affected plants are better destroyed. Overfeeding with nitrogen and high humidity promote the spread of the infection.

5) Spittlebug froth is caused by pinkish-yellow cicadellid nymphs about 3 mm long that suck sap and deform young plants; the foam is their protective covering. It does not cause great harm unless there is a mass outbreak. It is sufficient to wash them off with a hose and then prophylactically treat with a garlic infusion.

6) Spider mite appears with very dry, hot summers. Preventively use infusions of onion skins, garlic, yarrow, dandelion, or potato tops. With severe infestation acaricides may be used.

7) When affected by leaf and gall nematodes, brown spots appear between the veins on leaves; heavily infested plants may die. Remove affected leaves; with severe infestation destroy the entire plant.

8) In England the main "plague" of asters is verticillium wilt. The fungus Verticillium lives in the soil and participates in the decomposition of dead plant parts, being a useful member of the soil community. However, if it enters a plant through wounds on the roots, its mycelium penetrates the vascular system and the fungus becomes a pathogen. The plant's vascular system becomes blocked and shoots begin to die. This disease is called verticillium wilt. All affected plants are destroyed. Prevention is a good cropping and soil management background.

Use: they look attractive in group plantings on lawns, rock gardens and slopes. Asters are suitable for cutting, especially tall varieties. Inflorescences of perennial asters are usually cut in a half-open stage early in the morning or late in the evening when there is still much moisture in the plants. Store cut flowers in cool places. To avoid gaps in cutting, it is convenient to have two plots with planting dates staggered by 2-3 years, then clumps can be divided every 5-6 years. In cut bouquets many species and varieties last in water for up to 10-15 days. Before placing them in a vase of water, split the ends of the stems.