Asters are loved for their unpretentiousness and beautiful flowering. But these flowers also have disadvantages: the plants attract pests and have weak immunity to diseases.
The most dangerous diseases for asters are fusarium, jaundice, black leg and gray rot. And among insects, aphids cause the greatest harm to beautiful asters. But asters can be completely protected from all these misfortunes. It is enough to recognize the problem in time and choose a way to solve it. And some troubles with asters can be completely avoided if you take preventive measures.
Fusarium
Fusarium most often infects annual asters. The disease can be identified by one-sided damage to parts of the plant: leaves and stems are covered with dark stripes, but only on one side.
The mycelium of fusarium penetrates the plant organs through the roots and, growing, blocks the vascular system. As a result, the leaves, buds and the entire plant wither. In diseased asters, the leaves first turn yellow, then brown and curl. Dark stripes of an oblong-oval shape appear on the stem and at the root collar. Pinkish pads - fungal spore-bearing bags - can be found in the lower part of the stem.
Favorable conditions for the development of fusarium are high humidity of air and soil, as well as a temperature of 20-25 ° C.
Measures to combat fusarium:
- reducing the acidity of the soil to a neutral value (pH = 7), since the mycelium dies when the soil is limed;
- planting varieties resistant to viral diseases;
- timely control of aphids, which are carriers of the disease;
- seed treatment before sowing;
- when the first signs appear, spray the plants with copper oxychloride (50 g per 10 l of water).
Jaundice (mosaic disease)
The disease is caused by a virus that is carried by aphids and leafhoppers. It manifests itself as lightening of the veins on the leaves, and then general chlorosis of the asters. The buds turn green, and the plants stop growing, becoming bushy.
Measures to combat jaundice:
- control of leafhoppers and aphids - the main carriers of the disease;
- treatment of plants with a 0.1% solution of Actellic, a 2% solution of Pyrethrum or a decoction of yarrow (800 g of dry grass per 10 l of hot water, boil for 2 hours) with the addition of a small amount of soap to the finished solution;
- digging up and destroying diseased plants.
Black leg
The main symptom of this disease is thinning and blackening of the base of the stem at soil level. Aster seedlings suffer especially from black leg. Affected plants lie down and die within a few days. The pathogen overwinters safely in the soil. It likes an acidic and highly humid environment best of all.
Measures to combat black leg:
- pre-sowing disinfection of soil and garden tools;
- pre-sowing seed treatment in a solution of any fungicide (Maxim, Fitosporin-M) according to the instructions or soaking the seed in a dark pink solution of potassium permanganate for half an hour;
- maintaining the soil in a moderately moist state (to prevent the disease, the substrate can be sprinkled with dry sand);
- removal of diseased plants and immediate transplantation of seedlings into fresh soil.
Gray rot
This is a fairly common disease that affects many crops in the garden and vegetable garden. It does not bypass asters. Moreover, the target is all parts of the plant: leaves, stems and flowers. At first, brown spots without edges appear on them, and then the whole plant is covered with a smoky coating. Most often, the disease manifests itself in rainy and cool weather.
Measures to combat gray rot:
- spraying asters with copper-containing preparations (1% Bordeaux mixture, 0.5% copper oxychloride) for a month at intervals of 10 days;
- removal and burning of heavily damaged plants.
Aphids
Of all the pests of asters, aphids take first place. It feeds on plant sap, causing them to weaken quickly, shoots to become deformed, flower petals to curl and become discolored. Aphids reproduce especially actively in dry and hot summers – then whole colonies of this pest can be found on asters.
Measures to combat aphids:
- treating asters with a decoction of tomato tops (place 4 kg of green mass in a bucket, fill with water, boil over low heat for 30 minutes, strain; dilute 3 liters of decoction in 10 liters of water, add 40 g of crushed laundry soap and spray the plants);
- use of the drug Inta-Vir (in case of severe damage to plants) – 1 tablet per 10 liters of water.
Spider mite
Unlike aphids, the mite attacks asters in hot summers. Its presence is characterized by the appearance of brown webbing on the underside of the leaf. The leaves wither, dry up and fall off.
Measures to combat spider mites:
- spraying with an infusion of garlic, onion peel, garlic, yarrow, dandelion or potato tops every 5 days (2-3 times);
- pollinating plants with sulfur mixed with lime (1:1);
- in case of severe damage, the use of insecticides is indicated.
Take care of your fragile asters, and then they will decorate your garden with bright and elegant "stars" of their buds right up until the cold weather.