Rhododendron leaves turn yellow: why and what to do for treatment

The most beautiful, profusely flowering rhododendrons are forever imprinted in the memory of everyone who has ever seen them. But often all the leaves of your favorite rhododendrons turn yellow. Responsible gardeners must be clear about the causes and remedies for this problem. Only in this case, the plants will actively develop and will be able to please the owners for many years without any problems.

Causes of yellowing

Many factors affect plant he alth. Therefore, the causes of yellowing of foliage in rhododendrons are different.

Irrigation failure

Rhododendron is a moisture-loving plant.Therefore, with irregular and insufficient watering, especially in the hot season, the leaves become lethargic, quickly turn yellow and partially fall off. It is necessary not to pour the rhododendron, otherwise the root can simply rot. With stagnant water, yellowing of the foliage is also observed.

Lighting

Rhododendrons, especially those growing in the southern regions, suffer from intense solar radiation in summer. The leaves are the first to signal a problem - they turn yellow and dry out. They are shaded with shade nets, dense agrofiber or sheets of colored polycarbonate. Rhododendrons grow best in partial shade.

Wrong ground

Rhododendron belongs to the extensive Heather family and requires acidic soil to grow. Only then will the plant be able to absorb nutrients from the soil. Usually the soil for Heathers consists of acidic high-moor peat and rotted coniferous litter.To maintain the required level of acidity, regular acidification of the soil is carried out. Use citric acid, colloidal sulfur, electrolyte.

Damage to the root system

The root system of the rhododendron is fibrous, located in the upper layer of the soil. It is sensitive to damage and does not differ in strength of growth. During agrotechnical measures (loosening, weeding), it is easy to damage it. This will cause the leaves to turn yellow. Overheating of the soil during the hot summer months will also cause the foliage to change color.

Exit - shading plants or planting in the scattered shade of large trees. A good option would be landing under conifers. Soil mulching will help save the root system from overheating and excessive evaporation of moisture. Suitable sour (horse) peat, moss, softwood sawdust and pine needles.

Pests

Pests bring many problems to cultivated plants, unfortunately, rhododendrons are no exception. And often, pest infestation is one of the causes of yellowing leaves.

Rhododendron bug

When affected by this pest, the leaves lose their usual color and become light, pale, and later acquire a yellowish tint. With severe damage, the leaves curl and then fall off. On the underside of the leaf, sticky traces of insect excrement are visible. For the fight, insecticides BI-58, Karbofos are used. Moreover, several treatments should be carried out.

Mealybug

This pest breeds actively in warm and dry conditions, high humidity prevents its reproduction. Mealybug resembles small lumps of cotton wool. They attach to the surface of the leaves, settle in their internodes.

It is important before chemical treatment of the plant to try to mechanically clean all the affected parts from the worm. Use cotton swabs and soapy water. And only then it is worth spraying with a systemic insecticide; Aktara, Konfidor will do.

Aphid

When affected by such a common pest as aphids, the leaves of rhododendrons gradually lighten and acquire a yellowish tint. Aphids usually settle on the underside of the leaf. Control measures - spraying with insecticides - Aktellik, Nurel D, Konfidor.

Black thrips

When affected by thrips, the upper surface of the leaves is covered with grayish holes, the bottom - black holes. The affected areas turn gray, then turn yellow and fall off en masse. Control measures - spraying with insecticide solution

Khrushch

The root system can also be damaged by such a dangerous pest as the larva of the May beetle (Khrushch). This leads to yellowing and leaf fall. With severe damage, even shoots dry up.

Diseases

Rhododendrons are often affected by various diseases, and often this is the cause of yellowing, as well as leaf fall.

Septoria

Is the most dangerous fungal disease of rhododendrons. With septoria, small red spots appear on the leaves, which quickly increase in size and brighten. Then the foliage turns yellow, dries up and falls off. Without timely help, the rhododendron can be left completely without foliage. Fighting it - removing the diseased part of the bush, as well as treating with fungicides, for example, often use Ridomil Gold.

Chlorosis

In many plants, including rhododendrons, the cause of yellowing of foliage is non-infectious chlorosis. This is especially evident in the spring, at the beginning of the season. Chlorosis occurs when there is a deficiency of nitrogen and iron in the soil. With chlorosis, the foliage becomes light, yellowish or covered with spots of a characteristic shade.

Fusariosis

Dangerous fungal disease of the root system. When affected by rot, the leaves first turn yellow and dry, then the shoots dry out.

Requires quick treatment, with fungicides, otherwise the plant will die quickly.

What is this process

Yellowing of leaves in rhododendrons (azaleas) can occur both due to natural biological causes, and as a result of improper agricultural practices. It is especially dangerous if the change in leaf color is accompanied by the appearance of various spots. This will most likely be the start of a disease or pest attack.

If turned yellow in autumn

Change in color by autumn is a completely natural process. Depending on the variety, the foliage of rhododendrons becomes yellowish, brown or red. In this case, the gardener should not worry, but need to carry out a sanitary cleaning, removing all dried leaves and twigs.

If the stem has undergone yellowing

If the stem of a rhododendron began to turn yellow, then, in most cases, you need to pay attention to the plant's nutrition scheme. It is advisable to use special fertilizers for Heather; in addition to top dressing, they also acidify the soil.

Prevention

For prevention, it is necessary to carry out systematic spraying, as well as spilling drugs against diseases and pests. It is necessary to monitor the frequency of watering, at the same time avoid overflows.

And of course, keeping the soil at the right level of acidity and shade during the hot summer months will help keep the foliage he althy and green.