Rhododendron is a plant from the Heather family. It is grown in rooms and greenhouses. A flower, like any other plant, is susceptible to disease and pest damage. Therefore, many gardeners are wondering why rhododendron leaves turned brown, where the rot came from. There are simple ways you can cure, and then prevent, rhododendron diseases.
Types of rot affecting the plant
There are various types of rot, which have their own symptomatic course and treatment methods.
Root rot
The causative agent is a fungus that spreads to the root system and stem. Damage can be seen both throughout the plant and on individual shoots. First, the bush begins to fade, then the leaves dry up without noticeable external changes, the buds turn red, and die.
Root rot
If you cut the shoots, a brown layer is visible. When digging on the roots, brown color and rot is visible. The plant dies in a matter of days. The flower begins to hurt if the rhododendron was planted on arid soil with an acidic environment. Diseases are susceptible to young plants that have recently been transplanted. The infection spreads through the root, passes to the upper part of the stem.
There are no treatments. You need to dig a bush and burn it to avoid infection of neighboring plants. Subsequently, it is necessary to adjust the acidity of the soil at this place, and the correct watering regime for a new seedling.
Gray rot
The causative agent is the ash-gray Botrytis fungus. It lives in untreated soil and on the remains of other plants. By appearance, the concentration of the fungus in the form of mycelium is immediately determined.
Note! Contamination is promoted by high humidity, so gardeners should be wary of damp weather. For the disease to develop, the presence of dead tissue in the plants is sufficient, since the fungus is not able to multiply on living cells. When infection occurs, the fungus secretes toxins that spread to nearby living tissue and infect it.
The disease includes the following symptoms:
- brown spots on stems, buds, leaves;
- the surface of the damaged area dries and begins to crack;
- sclerotia are formed, which have a round, convex shape.
A distinctive feature of the disease is that the fungal growth is not white, but gray or black. This form of the disease is resistant to negative environmental factors, survives 2-3 years.
Methods of treatment: combating the pathogen with pruning, prophylactic spraying of the affected and neighboring plants with a solution of baseazole.
Gray rot
Late blight
The causative agent is the fungus Phytophtora cinamomi. A plant can get sick from neighboring infected flowers. The following conditions contribute to the formation of the fungus:
- plentiful watering;
- lack or poor drainage;
- high humidity.
Symptoms of infection and spread of the disease:
- dry leaves, which spreads to individual branches;
- lack of restoration of leaf density at night or in the morning;
- the branches turn yellow, then the color change is also characteristic for the whole plant;
- the roots turn brown, rot forms;
- brown spots in the area of the root neck or the beginning of the stem;
- rot on wood;
- gradually a gray or black spot forms on brown spots, which is a symptom of the formation of fungal spores;
- in the future, if untreated, the whole plant withers and dries.
Note! If the flower is completely dead, this does not mean that the infection has disappeared. It remained in the soil, therefore, the risk of infection of neighboring crops increases.
Methods of treatment: periodic spraying of infected plants with Bordeaux fluid, and if the flower is severely affected, it is dug up and burned.
Fluoride rot
Rhododendron bud rot
The plant infects the fungus Sporocybe azaleae. The causative agent was first discovered in the United States, and prevention and treatment measures were also studied there. Most often, the disease develops in the largest and ruling rheodendron. A characteristic feature of the defeat is the change in the shade of the buds to brown or brown. Without treatment, the bush dies.
The pathogen from the buds often goes to the branches, infecting the entire shrub. It is much more difficult to save him, you have to cut whole meters of shoots.
Methods of treatment: every three weeks, all parts of the plant are sprayed with preparations containing copper.
Bud rot
The main diseases of rhododendron and methods for their treatment
Allocate various types of infectious infection.
For your information! Not everyone knows why rhododendron leaves turn brown. To avoid this, you should prophylactically spray the flower with various drugs, strictly adhering to the instructions for the use of the insecticide.
There are three main forms of bush diseases:
- fungal diseases of rhododendron. The pathogen spreads through the soil or when the spores are transported by wind. Damage is noticeable in any part of the plant. Plots of darkening are formed, a rounded formation having a white, gray, black shade. Rhododendron chlorosis is a prime example of a fungal disease;
- infection. This is a defeat by various bacteria. The disease can be found in the soil or carried by insects. Gradually, the pathogenic microorganism spreads along the roots, trunk, leaves, shoots, leading to drying out and death of the parts. The pathogen usually spreads to many parts of the shrub. Therefore, it is necessary to burn it completely in order to avoid the spread of infection to neighboring plants;
- non-infectious causes. Negative environmental factors act that lead to impaired growth, flowering, and the fact that the leaves of the rhododendron are curled. This may be nitrogen starvation, poor-quality soil, soaking. To maintain shrubbery, it is necessary to improve the quality of the soil, apply fertilizer and water according to the schedule.
In order not to confuse the types of disease, you should familiarize yourself with their symptoms. For each type of infection and adverse growth, there is a solution.
Tracheomycotic wilting: when leaves curl
Infection comes from the fungus Fusarium oxysporum. This is a parasite that provokes the following symptoms:
- brown formation at the roots, subsequent rot;
- the spread of spores throughout the plant, which blocks the movement for nutrients;
- leaves lose their elasticity, become lethargic, curl up, brown spots appear on the rhododendron;
- falling leaves of joint petioles;
- a white-colored mycelium is formed on the trunks.
Note! If the gardener cuts off only the visible infected parts, the spores will remain in the roots and remaining stems. Further, the pathogen will spread to neighboring healthy flowers.
Methods of treatment: burning the entire plant along with the root system, spraying and pouring with a solution of baseazole for preventive purposes.
Shoots die off
The disease spreads to rhododendrons, which are planted in the shade without the presence of sunlight. A fungus from the genus Phytophtora cactorum Leb spreads over the flower. The main symptoms of the disease:
- the kidneys do not bloom;
- gradually the buds and shoots acquire a dark color, die off.
Methods of treatment: burning damaged leaves, shoots, after eliminating the flowers, spray with drugs containing copper every two weeks.
Bacterial root cancer
The disease is caused by the bacterium Agrobacterium tumefaciens. It secrete plasmids that transform plant cells. Sometimes a pathogen can infect a person, causing infection symptoms in people with reduced immunity.
Shrub gets sick, acquiring the following symptoms:
- the formation of growths on the roots, which become dark and hard, preventing the flow of nutrients into the trunks, shoots and leaves;
- growth retardation, weak flowering;
- gradually in the areas of growths rot forms.
Important! If the bacterium has not been completely destroyed, it will remain on the remains of the plant and in the soil, causing infection of the following plants.
Methods of treatment: the affected shrubs are sprayed with Bordeaux liquid, and if the bush was severely affected, they dig it out and burn it.
Pest diseases
There are many types of pests that can cause rhododendron diseases:
- furrowed weevil. Damages leaves - eats large holes in them. If many larvae appear, the entire shrub withers and dies. Spraying is carried out by descis, a splender;
- spider mite. The leaves on which the pest is located turn yellow, change shape, turn brown and dry. Spraying is carried out using an actellik, fufanon;
- acacia false shield. The parasite pierces the bark, attaching itself to the branches. The affected plant does not bloom, gradually dries and dies. Treatment is carried out with any drug with phosphorus, for example, fufanon;
- tobacco thrips. Parasites damage buds that do not open, turn yellow and fall. The flower is treated with phosphorus-containing agents, for example, phytoerm;
- A new american azalea bug. Because of it, yellow leaves with black spots like resin appear. Rhododendron leaves twist, dry and fall off. Treatment is carried out by spraying with a soapy solution of tobacco.
Note! Usually parasites fall on leaves and stems. They can be seen with the naked eye. When observing a large number of insects, treatment should be started immediately.
Furrowed weevil
Anthropic spotting
The disease is formed due to the fungus Gloeosporium rhododendri. On the leaves appear areas of dead tissue of red-brown color. The leaves dry out quickly, spores of rounded shape and dark color form on them. Gradually, the disease moves to stems that dry out.
Methods of treatment: pruning of affected parts, spraying with Bordeaux fluid.
Nitrogen starvation
This is a disease manifested by a lack of nitrogen and potassium in the soil. Leaf plates turn light. Shoots are formed weakly, flowering does not occur. On the sheets, spots of yellow, and then brown, form. Gradually they disappear. To eliminate the ailment, you should add nitrogen top dressing.
Winter drying
This is not a parasitic disease that resembles the death of shoots. The disease occurs after a harsh winter with severe frosts. When the soil thaws, the leaves curl, lose elasticity, turn brown and dry. This indicates a lack of moisture and damage to the internal parts by severe frosts. When the flow of water along the inside is normalized, the rhododendron will return to normal.
Note! It is necessary to make abundant watering and spraying up to several times a day.
Bloating (thickness)
Otherwise, the condition is called a wax disease. It is caused by Exobasium mushrooms. There is a characteristic symptomatology:
- deformation and thickening of leaves;
- the leaf plate begins to turn red;
- the formation of a wax coating, consisting of spores;
- damaged areas dry and crack;
- flowering is absent or weak.
Methods of treatment: pruning of damaged parts, spraying with Bordeaux fluid.
Sunburn
This occurs with sharp fluctuations in temperature. Foliage heats up and evaporates moisture. It becomes brown, dry, spots appear. For prevention, it is recommended to plant a bush in a dark place. If this is not possible, shelter should be done above the bush from the scorching sun.
Sunburn
Cercosporosis
If rhododendron has brown leaves, not every gardener knows what to do. The disease is caused by the fungus Cercospora rhododendri Ferraris. It provokes the fact that rhododendon has brown leaves, and if there is additional humidity in the area, they are covered with a coating containing spores. Treatment is carried out using fungicidal agents.
Cercosporosis
Jamming
If little oxygen reaches the root system of the shrub, leaf blades become dull, green. Shrub for no apparent reason discards foliage. Emerging shoots are soft. The root ball is quickly destroyed.
Often the disease is formed where the soil is rotten, heavy, with poor drainage. For treatment, you need a water and breathable substrate and drainage. Watering is limited.
Plant Prevention and Protection
In summer and spring, plants should be periodically sprayed with insecticides, fungicides. The soil should be moderately moist, plants do not like large amounts of water, but also do not grow in arid places. The soil must be well drained so that growth and flowering occur.
Note! Most often, rhododendron suffers from a fungal infection. Gardeners prefer to spray the bushes with Bordeaux liquid, which destroys most types of mushrooms.
Rhododendron is often susceptible to diseases, the treatment of which depends on their cause. It can become infected with a bacterial, fungal infection. But also the gardener must take into account that certain conditions are necessary for a flower to grow and bloom successfully. If the leaves of the rhododendron fade, this article will tell you what to do if you carefully re-read it again. And it is advisable not to delay the treatment, so as not to lose the whole bush overnight.
