Dahlias are a decorative culture that is characterized by lush bushes and continuous flowering throughout the summer. Many flower growers like the flower, but due to the high susceptibility of the plant to pests and diseases, its popularity is gradually declining. The problem is completely solved if timely preventive treatment of the bushes and proper storage of tubers in the winter are carried out.
Brief description of the plant
Dahlia is an annual or perennial herb, depending on the species. The culture belongs to the Astrov family. In the wild, the plant can be found in the mountainous regions of Mexico, Chile, Guatemala, Colombia. Modern dahlias are a complex hybrid that has gone through lengthy breeding work. As a result, varieties were obtained that have a diverse color of petals, as well as the size and shape of the flowers.
Dahlias are susceptible to disease and pests.
Perennial dahlias have a tuberous, branched root, in which an accumulation of moisture and nutrients accumulates. Thanks to this, the plant is able to provide itself with everything necessary. Dahlias form erect hollow stems 50-200 cm high. Cirrodivided dense leaves of a dark green hue are located along their entire length. Dahlia flowers have the shape of a basket, in which reed, marginal, middle and tubular petals can be located. Their color is monotonous and colorful.
Important! Dahlia inflorescences come in a variety of shades except black, blue, and blue.
This crop does not winter in open ground
With the arrival of the first frosts, tubers must be dug up and sent for wintering to a cool, dry place. In the spring they are planted. As soon as the earth warms up well, the plant begins to grow. Dahlia blooms in late June - early July and lasts until late autumn.
What causes the disease?
Hybrid forms of dahlias partially lost their natural immunity, and the susceptibility of plants to the effects of pathogens increased. Any errors in the care and storage of tubers can trigger the development of diseases. When growing a flower, it is important to adhere to preventive measures, since not all diseases of dahlias are treatable.
Improper care
Various factors can provoke the development of diseases. All of them are associated with improper care of the plant.
Common reasons:
- storage of tubers at high or too low humidity;
- incorrect division of the rhizome in the spring;
- lack of nutrition;
- excessive or scarce watering;
- lack of preventive treatments;
- thickening of landings;
- crop rotation failure.
Important! Often, pests are carriers of diseases, so it is important to periodically inspect the bushes and process at the first sign of settlement.
Common diseases
Dahlias are most often affected by fungal diseases. When growing a flower on a site, you need to know how they appear and what to do if signs of infection appear.
Leaf spotting
A provoking factor in the development of the fungus is the thickening of the plantings. Against this background, the level of ventilation between plants decreases, which leads to an increase in humidity. Dahlia leaf disease can be detected by light yellow spots of irregular shape and with a blurred border. Subsequently, their shade becomes brown, and the border acquires a dark color.
Important! If the spotting is not treated, then the plant cannot fully bloom.
You can get rid of the disease with drugs:
- Fundazole;
- copper sulfate;
- Oksikhom.
Leaf spotting develops slowly
Gray rot
This disease can also be the reason why dahlias do not grow and bloom. During it, brown spots appear on the leaves, which, with increased humidity, are covered with a gray-white edge.
Note! If the disease develops when the plant is about to bloom, then watery spots appear on the buds, which eventually rot.
Preparations for the fight against gray rot:
- Topsin;
- Benleit;
- Rovral.
Verticillus and Fusarium wilt
These diseases have similar symptoms, but they have different pathogens. Initially, the fungus affects the roots and tubers of the plant, then moves up and becomes the reason why the dahlias curl and wither. Affected parts of the plant become pink or brown. For treatment, you must use Fundazole or Oxychom.
Brown rot
The disease affects young shoots of plants at the seedling stage. A too deep landing of tubers is a provoking factor. This leads to the fact that the sprouts are weakening, since they do not have enough strength to break out.
Products for the treatment of brown rot:
- Alirin;
- Fitosporin;
- Gamair.
Other diseases
Dahlias also affect other diseases. Each of them has its own characteristic differences.
The reason why dahlias bloom and grow poorly may be:
- Powdery Mildew It appears white plaque on the foliage. As the disease develops, it acquires a dirty brown hue. Subsequently, the leaves completely fade, and the plant ceases to bloom. When powdery mildew appears on dahlias, it is necessary to treat the plant with Skor or Topaz.
- Blackleg. A disease develops when a plant is planted with seeds or cuttings. Provoking factors are excessive watering and cool air temperature. A characteristic sign of damage is a black rim at the base of the seedlings. Subsequently, the stem in this place is thinned and cracked. For treatment, seedlings are recommended to be watered with solutions of Previkur Energy or Maxim preparations.
You can cope with the problem if you can determine the disease
Incurable diseases
Some diseases cannot be treated. The only way in this case is to prevent the mass spread of pathology. To do this, the infected plant remains must be destroyed.
Incurable Dahlia diseases:
- Mosaic virus. It appears on the leaves with light stripes. Then they increase in size, and the entire plate becomes pale. In this case, the leaves do not fall.
- Tuber galls. During the disease, bloated warts appear in the area of the root neck. As a result, plant shoots grow deformed, and cannot fully develop.
- Mycosis. The initial sign of damage is that the leaves of the plant begin to turn yellow, as with a lack of water. But watering does not solve this problem. As a result, the entire aboveground part completely fades.
- Fusarium It is characterized by brown spots that appear on the shoots and leaves. Then they grow and cause the death of the plant.
Pests
Often, pests affect the culture. Before you start a fight with them, you need to find out who can eat dahlias and what means are better to use.
Aphid
If aphids appear on dahlias, the pest is placed on their young shoots and leaves. The insect forms entire colonies, so it is impossible not to notice them. As a result of damage to aphids, plant growth slows down, the buds are deformed, and the bush can completely stop blooming.
Aphids on dahlias, how to treat bushes? You can fight this harmful insect with the help of drugs: Intavir, Actellik or Decis.
Aphids will not allow a plant to develop fully if it is not destroyed
Nematodes
These worms damage the shoots, leaves and buds of a plant. A characteristic sign of damage is light spots, which subsequently darken and die off. As a result of the activity of nematodes, the bush noticeably lags in growth, shoots and leaves are deformed.
The affected dahlias must be dug up and burned. In the same place, the flower can not be re-planted. To combat the pest, you need to use marigolds, placing them somewhere nearby. The smell of this plant repels nematodes.
Vegetable bugs
Insects feed on the young leaves of the plant. As a result of this, metabolic processes in the tissues are disturbed. Initially, brown spots appear on the leaves, and then the plates are completely wrinkled.
With a small number of pests, you can get rid of them in a folk way using a solution based on Coniferous soap. If the lesion is massive, it is necessary to use Mospilan or Iskra-M preparations.
Important! It is necessary to carry out the processing of the bushes in the morning, as during this period the bugs are inactive.
Gastropods
These creatures are activated at night. They are attracted to the young leaves of the plant. Pests gnaw holes in them, and sometimes eat them completely. This negatively affects the decorative bush.
To destroy slugs, it is necessary to use preparations based on metaldehyde. In dry weather, you can pour wood ash, red pepper or superphosphate at the base of the bushes. To destroy slugs, they make beer traps, because they like the smell of this drink.
Greenhouse Whitefly
A small white butterfly that lays eggs on the back of the leaves of a plant. Gluttonous larvae appear from them. To destroy whiteflies, it is necessary to water the plants with Aktara working solution and at the same time spray the foliage with Mospilan or Actellik.
Deer or Shaggy Bronze
During flowering, large black insects appear on dahlias. Their size is about 1 cm. They feed on the petals, stamens and pistils of the flower. Spraying with insecticides does not give the desired results, since new ones come to replace the dead pests. The only way to save dahlias is to collect the beetles by hand.
Other
Sometimes dahlias can suffer from gamma scoop moths. This pest is activated in late spring - early summer. The insect eats nectar of flowers without causing serious damage to the plant.
The danger is represented by its larvae that damage dahlia tubers. As a result of their vital activity, the plant begins to fade. For the destruction of caterpillars, it is recommended to use the drug Fufanon.
Preventative measures
What if dahlias do not grow? Such a question can be heard from many gardeners. Slow growth is most often caused by diseases and pests. In order to prevent such a problem, preventive measures must be observed.
Basic Rules:
- Before planting, the tubers must be soaked in a solution of insecticide and fungicide for 15 minutes.
- Before laying a dahlia for storage of its rhizome, it should be dried.
- Observe crop rotation.
- Store plants in the winter in a cool, dry room equipped with ventilation.
- Avoid waterlogging of bushes.
- Spray plants with special preparations twice a season to prevent infection.
Dahlias do not grow well, what to do in this case, it becomes clear when identifying the root cause. In order not to subsequently encounter such a problem, it is necessary to monitor the condition of tubers in winter and bushes throughout the season.
