Rhododendron diseases: why the leaves turned brown

Rhododendron is a plant from the Heather family. It is grown in rooms and greenhouses. A flower, like any other plant, is susceptible to diseases and pests. Therefore, many gardeners are wondering why the leaves of the rhododendron turned brown, where did the rot come from. There are simple ways that you can cure and then prevent rhododendron disease.

Rot types affecting the plant

There are various types of rot, which have their own symptomatic course and methods of treatment.

Root rot

The causative agent is a fungus that spreads to the root system and stem. Damage can be seen both on the whole plant and on individual shoots. First, the bush begins to wither, then the leaves dry up without noticeable external changes, the buds turn red, die off.

Root rot

If you cut off the shoots, a brown layer is visible. When digging, brown color and rot are visible on the roots. The plant dies in a matter of days. The flower begins to ache if the rhododendron was planted in arid soil with an acidic environment. Young plants that have recently been transplanted are susceptible to diseases. The infection spreads through the root to the top of the stem.

There are no cures. You need to dig up a bush and burn it to avoid contamination of neighboring plants. Subsequently, it is necessary to establish the acidity of the soil at this place, and for a new seedling the correct irrigation regime.

Gray rot

The causative agent is the fungus Botrytis ash gray. It lives in uncultivated soil and on the remains of other plants. By appearance, the concentration of the fungus in the form of mycelium is immediately determined.

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.

Treatment methods: control of the pathogen by pruning, prophylactic spraying of the affected and neighboring plants with a solution of foundationol.

Gray rot

Late blight rot

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 a fungus:

• abundant watering;
• lack or poor drainage;
• high humidity of the environment.

Symptoms of infection and spread of the disease:

• dryness of 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 characterized for the whole plant;
• the roots turn brown, rot is formed;
• brown spots in the area of ​​the root collar 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;
• further, in the absence of treatment, the whole plant withers and dries up.

Treatment methods: periodic spraying of infected plants with Bordeaux liquid, 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 studied there. Most often, the disease develops in the largest rhododendron and ketevba. A characteristic feature of the defeat is a change in the shade of the buds to brown or brown. Without treatment, the bush dies.

The pathogen from the buds often passes to the branches, infecting the entire shrub. It is much more difficult to save it, you have to cut out whole meters of shoots.

Treatment methods: every three weeks all parts of the plant are sprayed with preparations containing copper.

Rot of buds

The main diseases of rhododendron and methods of their treatment

There are various types of infection.

There are three main forms of shrub disease:

• fungal diseases of rhododendron. The pathogen is spread through soil or by wind-borne spores. The damage is visible in any part of the plant. Areas of darkening are formed, a rounded formation that has a white, gray, black tint. Chlorosis of rhododendrons is a prime example of a fungal disease;
• infection. This is a defeat by various bacteria. The disease can be found in soil or carried by insects. Gradually, the pathogenic microorganism spreads along the roots, trunk, leaves, shoots, leading to drying out and death of parts. Typically, the pathogen spreads to many parts of the bush. Therefore, it is necessary to burn it completely to avoid spreading the infection to neighboring plants;
• non-infectious reasons. Negative environmental factors act, which lead to impaired growth, flowering, and the fact that the leaves of the rhododendron curl. This can be nitrogen starvation, poor-quality soil, soaking. To preserve the shrub, you need to improve the quality of the soil, fertilize and water according to the schedule.

In order not to confuse the types of the disease, you should familiarize yourself with their symptoms. There is a solution for each type of infection and adverse growth.

Tracheomycotic wilting: when leaves curl

Infection occurs from the fungus Fusarium oxysporum. This is a parasite that provokes the following symptoms:

• the formation of a brown color at the roots, subsequent rot;
• the spread of spores throughout the plant, which blocks the movement of nutrients;
• leaves lose their elasticity, become lethargic, curl up, brown spots appear on the rhododendron;
• falling leaves of joint petioles;
• a white mycelium forms on the trunks.

Treatment methods: burning the whole plant along with the root system, spraying and watering with a foundationol solution for preventive purposes.

Dying off of shoots

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:

• buds do not bloom;
• gradually buds and shoots acquire a dark color, die off.

Methods of treatment: burning damaged leaves, shoots, after removing the flowers, spraying with preparations containing copper is carried out every two weeks.

Bacterial root cancer

The disease is caused by the bacterium Agrobacterium tumefaciens. It releases plasmids that transform plant cells. Sometimes a pathogen can infect a person, causing symptoms of infection in immunocompromised people.

The shrub becomes ill, 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;
• rot is gradually formed in the areas of growth.

Methods of treatment: the affected shrubs are sprayed with Bordeaux liquid, and if the bush was severely affected, it is dug up and burned.

Pest diseases

There are many types of pests that can cause rhododendron disease:

• furrowed weevil. Damages leaves - eats out large holes in them. If many larvae appear, the entire shrub withers and perishes. Spraying is carried out with descis, splander;
• spider mite. The leaves on which the pest is located turn yellow, change shape, turn brown and dry out. Spraying is carried out using actellik, fufanon;
• acacia false shield. The parasite pierces the bark by attaching itself to the branches. The affected plant does not bloom, gradually dries up 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 off. The flower is treated with phosphorus-containing agents, for example, phytoverm;
• new american azalea bug. Because of it, yellow leaves appear with black spots like resin. Rhododendron leaves twist, dry up and fall off. Treatment is carried out by spraying with soapy water and tobacco.

Furrow weevil

Anthropose spotting

The disease is caused by the fungus Gloeosporium rhododendri. Red-brown patches of dead tissue appear on the leaves. The leaves dry out quickly, and spores of a round shape and dark color form on them. Gradually, the disease moves to the stems, which dry out.

Treatment methods: pruning the affected parts, spraying with Bordeaux liquid.

Nitrogen starvation

This is a disease that manifests itself when there is a lack of nitrogen and potassium in the soil. The leaf plates become light. Shoots are poorly formed, flowering does not occur. Spots of yellow and then brown color are formed on the sheets. They gradually disappear. To eliminate the disease, nitrogen fertilization should be applied.

Winter drying

This is not a parasitic disease that resembles shoot death. The disease occurs after a harsh winter with severe frosts. When the soil thaws, the leaves curl, lose their elasticity, turn brown and dry. This indicates a lack of moisture and damage to the internal parts of severe frosts. When the flow of water through the inner part is normalized, the rhododendron will return to normal.

Leaf swelling (thick leaf)

Otherwise, the condition is called wax disease. It is caused by the Exobasium fungi. There are characteristic symptoms:

• deformation and thickening of the leaves;
• the leaf plate begins to turn red;
• the formation of a wax plaque consisting of spores;
• damaged areas dry and crack;
• flowering is absent or weak.

Treatment methods: trimming damaged parts, spraying with Bordeaux liquid.

Sunburn

This occurs when there is a sharp fluctuation in temperature. The foliage heats up and evaporates moisture. It becomes brown, dry, spots appear. For prevention, it is recommended to plant a shrub in a dark place. If this is not possible, you should make a shelter above the bush from the scorching sun.

Sunburn

Cercosporosis

If the 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 brown leaves appear in rhododendon, and if there is additionally high humidity in the area, they are covered with a bloom containing spores. Treatment is carried out with fungicidal agents.

Cercosporosis

Locking

If little oxygen reaches the root system of the shrub, the leaf blades become dull, green. The shrub sheds foliage for no apparent reason. The emerging shoots are soft. The root ball quickly collapses.

Often the disease develops where the soil is rotten, heavy, and poorly drained. The treatment requires a water and breathable substrate and drainage. Watering is limited.

Prevention and protection of the plant

In summer and spring, plants should be periodically sprayed with insecticides, fungicides. The soil should be moderately moist, plants do not like a lot of water, but they also do not grow in arid places. The soil must be well-drained for growth and flowering to occur.

Rhododendron is often susceptible to diseases, the treatment of which depends on their cause. He can contract a bacterial, fungal infection. But also the gardener must take into account that certain conditions are necessary for a flower in order for it to grow and bloom successfully. If the leaves of a rhododendron wither, this article will tell you what to do if you read it carefully again. And it is advisable not to delay the treatment, so as not to lose the entire bush overnight.