Like any other plants, hydrangeas are susceptible to diseases and the reproduction of pests, although this happens extremely rarely. Sometimes growers notice that the plant leaves have turned yellow, aphid, fungus or viral damage.
All the main diseases of hydrangea garden by the nature of origin can be divided into two main groups:
Professional flower growers call several reasons for the defeat of this pest plant:
- soil contamination by pathogenic microorganisms;
- improper care of the plant;
- excessively high air humidity and frequent temperature changes;
- lack of nutrients.
The main diseases of hydrangeas and their treatment
Most often hydrangeas get sick with chlorosis. With this disease hydrangea leaves turn yellow and fall off, dryness and brittle branches appear, and gradual grinding of the inflorescences is observed. The disease is caused by a metabolic disorder that usually occurs with iron deficiency. Plants planted on soils with a significant amount of lime are more susceptible to chlorosis. Excess soil humus also leads to chlorosis. The development of chlorosis can also be caused by watering the plant with cold and undiluted water, excessive use of organic fertilizers.
Ignore chlorosis is not worth it, because this disease can lead to a complete loss by the plant of an attractive appearance. Moreover, hydrangea can stop blooming altogether.
Control measures: At the first signs of disease, the plant must be treated with a solution of potassium nitrate acid for 3 weeks: 40 g is diluted in 10 l of water.
After this treatment for several days, the plant should be treated with a solution of iron sulphate in the same concentration. To prevent the development of chlorosis, hydrangeas should be periodically fed with fertilizers containing iron.
Gray rot - a fungal disease that can cause the death of hydrangeas. Rot affects the entire plant - leaves, stem, buds and even flower stalks. When tissue is damaged by this fungus, their structure becomes soft and watery. A symptom of the disease - the appearance of wet spots with a gray bloom, which grow to a fairly large size. In dry weather, the stalks of the affected specimens dry out and fall off.
With the development of gray rot, rainy and damp weather is especially dangerous, because at high humidity the fungus spreads with rapid speed, infecting new areas of soil.
When these spots appear, you must immediately take measures to combat the disease. An important condition for preventing disease is the destruction of diseased leaves.
Control measures: If the rot has not spread to the whole plant, only the affected parts of the hydrangea are removed, and the healthy stems and leaves are treated with Bordeaux mixture or foundation. If the spots have spread to the stem - the plant must be excavated and destroyed.
White rot is a fungal disease that primarily affects the plant root system. Hydrangea roots begin to rot during the development of white rot, with the result that the plant does not receive the necessary nutrients. Soon the leaves and stems of the hydrangea turn brown and die. The causative agent of white rot is a pathogenic fungus that enters the soil with plant remains.
In the case when the white rot strikes young specimens, a white bloom forms on the leaves and shoots, resembling cotton wool in its appearance. After some time, black spots can be found in this raid - sclerotia. Effective against white rot are fungicidal drugs, such as Fitosporin.
There are two types of this fungal disease that affects the hydrangea:
- downy mildew, or perinospora;
Less commonly, hydrangea suffers from powdery mildew. It affects the leaves and stems of hydrangeas. Its first signs are the appearance of oily, later yellowing spots on the leaves, gradually darkening and increasing in size. A yellowish bloom appears from the bottom of the leaves, the same bloom can be on young stems. High air humidity and temperature 18-20 ° С contribute to the development of the disease.
Control measures: In the early stages of the development of a fungus, it is possible to get rid of it by treating affected plants with copper-soap liquid (150 g of green soap, 15 g of copper sulfate on 10 l of water). This liquid is harmless to plants, and its use in the early stages of development helps to completely get rid of the disease. If it was not possible to get rid of the fungus, then fungicidal preparations should be used.
Powdery mildew from the false form of this fungal disease can be distinguished using signs such as the formation of yellow-green spots on the leaves of a plant.
Pay attention to this photo: here are signs of such hydrangea as false and powdery mildew.
This disease is manifested by the formation of brown spots on the hydrangea leaves with a diameter of 5 mm. If you do not treat septoria, the leaves will soon completely darken and fall away from the stems. This disease can deprive the plant of all leaves.
Signs of this hydrangea disease can be seen in the photo below:
Methods of struggle:
- Timely remove fallen leaves affected by Septoria, so that the fungus does not infect other areas of the soil.
- Trim affected stems and leaves, slightly grabbing and healthy areas.
- In spring, spray hydrangeas with Bordeaux mixture and Profit.
The features of hydrangea leaf treatment in the treatment of this disease can be found in the photo below:
Another common hydrangea fungal disease that many growers face is rust. The disease manifests itself as a rusty color on the leaves, the disease may occur as a result of an excess of nitrogen in the soil.
Treatment of plants with copper chlorine oxide by spraying diseased and healthy leaves will help eliminate rust. To prepare the solution, 20 grams of copper should be dissolved in 5 liters of water. Also effective against rust drugs such as Topaz and Falcon.
The external manifestations of this hydrangea disease and its treatment are presented in this photo:
Too high humidity and cramping can cause an invasion of snails and slugs, which can greatly harm the plant. If there are too many harmful organisms, the plants are treated with such drugs as Karbofos, Fitoverm, Aktellik. Meta is recommended to use against slugs.
Having familiarized with the main diseases garden hydrangea and the methods of their treatment, each grower can independently protect their plants from death.
Hydrangea pests and control measures
Spider mite infects the leaves from the underside, causing them to yellow and marble, then to dry and fall off. At a temperature that is optimal for a tick (29-31 ° С) and humidity (35-55%), the development cycle of the insect takes about 7-9 days. The mite covers the underside of the leaf with a brown spider web. For the year he gives 12-15 generations. At low temperature (10-12 ° С) and high humidity (80-85%) its activity is significantly reduced.
Control measures: To get rid of such a hydrangea pest as a spider mite, the plant must be regularly sprayed with water. In treating this hydrangea disease, spraying the leaves of the plant with thiophos (5-7 g per 10 l of water) helps. You can process the hydrangea Actellik.
In conditions of closed ground, when the plants are distilled, the hydrangea can be affected by green leaf aphids.
Control measures: A good means of its destruction is the double spraying of plants with anabizin-sulphate solution. To do this, 15-20 g of anabizin sulfate is dissolved in 10 l of water. It serves as a radical tool in the fight against leaf aphids.