Contents
The ancient Aztecs and Mayans decorated the temples of the sun god with dahlias and used these flowers for their pagan religious rites. They originally called dahlias acoctyls. The flowers we know today got their name in 1803. Today it is customary to decorate household plots with dahlias. Many flower growers are fond of their reproduction. And this is not surprising, because these plants bloom very beautifully. However, like all flowers, dahlias need care. Most of all, flower growers are annoyed by pests of dahlias.
From this article you will find out which pests most often destroy dahlias. In addition, we will tell you about what diseases of dahlias exist and how to deal with them. Also in the article, a video on the topic will be provided, which will expand your knowledge on this topic.
Preventive treatment of tubers
Tubers should be treated with fungicides or sulfur. You can powder the tips of the tubers with the drug or dilute it in water and dip the roots into the solution. If you purchased liquid fungicides, then hold the dahlia tubers in the preparation for about 15 minutes. All work with chemicals must be carried out with rubber gloves. After processing, the tubers must be dried. This can be done by laying the tubers on a newspaper, cardboard or wooden base.
Do not dry tubers on concrete. The fact is that it draws out moisture, as a result of which dahlia tubers wrinkle prematurely. If you have several varieties of plants, then you can prepare several containers with a solution. 1 variety will be placed in each container, which means that there will be no confusion. Some growers make a treatment solution from a fungicide and a systemic insecticide.
It is worth noting that in many respects the need for preventive treatment depends on the climate in which dahlias will be planted. So, in a humid climate, the likelihood of the appearance of fungal diseases increases, while in a dry climate, this practically does not happen.
Varieties of diseases
Dahlias are prone to various diseases, most often these are fungal diseases. They develop in a humid climate and provided that the grower has planted flowers very densely. Next, the most common of them will be described, as well as advice on how to deal with diseases and their consequences.
Leaf spot
Dahlia leaf spot is caused by the fungus Entyloma dahliae. A sign of the disease are yellow-green spots on the leaves. Subsequently, they blur and become gray-brown with a pronounced border. Leaf spot results from poor ventilation between dahlia bushes due to densely planted plants.
To cure this disease of dahlias, fungicides are used. It can be Oksikh or Fundazol. Healthy dahlia bushes are treated with these preparations, and diseased plants are destroyed.
Gray mold
The causative agent of gray rot, or, as it is also called, botrytis, is the pathogenic fungus Botrytis cinerea. The first sign of the disease is the appearance of brown spots on the leaves, and then the whole plant is affected. Gray rot leads to drying of the leaves, drying out of the buds and deformation of the flower stalks.
If botrytis infects dahlias during the flowering period, then water spots appear on the inflorescences, as a result of which the tissues soften and the flowers rot. The disease develops due to excess moisture, which is the result of a thickened planting.
In the fight against the disease, fungicides are used in the same way as in the previous case. It can be Topsin, Fundazol, Benleit or Rovral.
Verticillium and fuariose wilt
The symptoms of these diseases are the same, although the causative agents of the diseases are different – Verticillium dahliae and Fusarium oxysporum. First of all, the roots and tubers are affected, they simply rot. After that, the leaves and apical parts of the buds and shoots wither. The affected dahlia is covered with a pinkish (fusarium) or brown (verticillium) coating.
The cause of the diseases is the same as in the previous cases – a violation of ventilation and the presence of excessive dampness due to a thickened planting. Affected tubers should be removed from the flower bed and burned. As a prophylaxis and treatment, plants should be treated with systemic fungicides. For example, Oksihom or Fundazol.
brown rot
The causative agent of this fungal disease of dahlias is the fungus Rhizoctonia solani. As a rule, young shoots and dahlias that are at the beginning of the growing season are affected by brown rot.
The disease develops due to too deep planting of tubers. Fungicides are used as preventive and therapeutic drugs. It can be Fundazol, Alirin, Fitosporin-M and Gamair.
Incurable diseases
There are several diseases of dahlias that are not treatable:
- mosaic virus. Pale green or yellowish stripes appear on the leaves of plants. If you find these symptoms on one of the bushes, then it must be urgently dug up and burned. Such an event will protect other bushes and minimize the possibility of infection.
- Tuberous galls. Nodular warts appear on the root collar. The affected tuber should be dug up as soon as possible. Alternatively, try to save the tubers at the end of the season by cutting off the affected areas from them. After that, the cut points are treated with fungicides. However, as practice shows, it is better to destroy such tubers and not use the infected soil for a year.
- Fuzarioz. Outwardly, it manifests itself as brown spots appearing on the stems. This leads to wilting and death of dahlias. Sick shoots need to be cut, and then burned. The remaining bushes must be treated, for example, with Bordeaux mixture (0,1%) or foundationol (0,1%).
- Mycosis. It manifests itself as a common lack of water – the dahlia turns yellow, and the shoots wither. So, you first need to water the beds and watch the bushes. If after 24 hours the leaves recover, then this is a lack of water, and if not, then mycosis. The disease is not treated, and the affected bush is dug up and burned. In the next 4 years, nothing can be planted on the contaminated land.
Pests and their control
There are many types of pests that love to infect dahlias. Next, we will consider the main types and methods of dealing with them.
Тли или Aphididae
Colonies of these pests are immediately visible to the human eye. A sign of their appearance on dahlias is the yellowing and curliness of the leaves, the presence of sticky secretions on them. These are sucking pests, which are also carriers of viral and fungal diseases.
If single colonies are found on dahlias, then they just need to be cut with leaves. If there are a lot of aphids, then dahlias need to be processed. This can be done with a solution of Green soap or insecticides, for example, Aktara, Fitoverm, Confidor and Decis.
Chrysanthemum and strawberry nematodes
These pests damage dahlia leaves, petioles, and buds. Light, darkening necrotic spots appear on the leaves at first. Nematodes can overwinter in the buds of dahlia tubers. Sometimes root pests of this species are also found. A sign of their presence is the lag of the bush in growth and the subsequent curvature of the stems.
Dahlias, in which nematodes are wound up, must be dug up along with a large piece of earth and burned. After that, on the land where the infected dahlias were planted, plants susceptible to the harmful effects of these pests can no longer be planted. As a preventive measure, you can water the soil with Ecogel, which strengthens the cell walls of dahlias. Marigolds also scare away the pest, so you can plant them near dahlias and other plants susceptible to this pest.
vegetable bugs
They feed on the leaf plates of dahlias, as a result of which the flow of nutrients is disturbed. Yellow brown spots appear on damaged leaves. Later, the leaf tissues shrivel and tear.
If the presence of plant bugs on dahlias is detected in time, then it will be enough to treat the dahlias with a solution of Green Soap. With the massive defeat of dahlias by bedbugs, more powerful tools are needed, such as Iskra-M or Mospilan. In the morning, the bugs are practically motionless, so the treatment of plants should be carried out at this time of day.
Scoop-gamma
Night butterflies of this pest fly in late spring and early summer. They feed on nectar and do not harm dahlias. However, these butterflies lay many eggs, from which caterpillars hatch, gnawing the roots of dahlias at the surface of the earth, as a result of which the plant fades.
If there are few caterpillars, then they can be collected manually. But with a massive invasion, you will need to use tools such as Bitoxibacillin and Lepidocide. Insecticides Fufanon and Iskra-M will also help in the fight against caterpillars. All the above preparations need to be treated with dahlias and their land.
Gastropods or slugs
They emerge in the shade, predominantly in wet weather, and are especially vigorous at night. They eat grooves in the leaves and gnaw through them. Often the leaves are completely eaten.
In the aisles, you can scatter ash, which irritates the mollusks, it is for them like glass for a person. However, this technique is ineffective, since after getting wet, the ash is no longer dangerous for slugs. Also, ordinary ground red pepper and superphosphate are used to destroy them. Metaldehyde preparations kill slugs. They are also scattered on the ground. You can also set traps for slugs and collect them manually.
greenhouse whitefly
Small butterflies with a size of 0,1 cm are sometimes found on dahlias planted in open ground. They usually attack flowers in greenhouses. They lay their eggs on the underside of a dahlia leaf. They hide under the leaves of dahlias. The larvae feed on the leaves, as a result of which spots appear on them. Greenhouse whitefly cocoons also form on leaves. It turns out that the foliage of dahlias serves as a home for these insects.
In pest control, insecticides are used, such as Iskoriy, Aktara and Mospilan. They are applied to the plant by spraying.
Olenka or shaggy bronze
The deer is a black beetle, larger than 1 cm. It eats pistils, stamens and petals of dahlias. It affects flowers from late spring to late summer. Female beetles lay their eggs in humus-saturated soil, where brown-headed white larvae hatch, which feed on dahlia roots and plant debris.
Usually there are not so many beetles, so they are simply collected from dahlias, and the larvae are removed in the process of loosening the soil.
To summarize
So, with a competent approach to the issue of caring for dahlias, there will be no problems with them. Well, if you already did something wrong, you can always use the tips presented in the article. In addition, we suggest you watch additional videos:
