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Beginning from spring until autumn, pelargonium grown as indoor and garden plants pleases owners fluffy caps of inflorescences, endure all the hardships and grow beautifully, requiring only a little attention and simple care. But sometimes lovers of indoor flowers complain that pelargonium loses its attractiveness, refuses to blossom, and its leaves turn yellow and wither. What can cause this behavior of the plant? Why does the pelargonium turn yellow leaves?
Errors of care leading to yellowing of pelargonium leaves
The change in foliage color, its lethargy and yellow tint are the most common signs of plant unhealth. The reasons for the same discomfort can be several. And among the most obvious are the mistakes of leaving, which led to the weakening of the bush:
- Too tight for the plant pot, in which the roots have already occupied all the volume intended for them, and pelargonium lacks moisture and nutrition.
- Lean irrigation that does not meet the plant's need for moisture and leads to yellowing of the edges, and then the drying of the leaves.
- Excess soil moisture can lead to more serious consequences - to decay and loss of the root system. And in this case, the leaves of the pelargonium turn yellow when the problem takes a serious turn.
- The yellow edges of especially adult leaves are a sign for the floriculturist that Pelargonium needs more intensive fertilizing, and fertilize the bush should not only potassium, nitrogen and phosphorus, but also trace elements, after foliar top dressing.
No less dangerous for pelargoniums are insect pests that parasitize both the green part of the plant and the soil.
Most often insects suffer from geraniums, grown in the garden or in balcony boxes in the summer.
In these conditions on the back of the foliage and in the sinuses can be found aphids, thrips, eating juices of the plant and becoming one of the reasons why the leaves on the pelargonium turn yellow. In the garden, in areas with heavy moist soil, juicy stalks of pelargonium attract slugs. Foliage and inflorescence suffer from caterpillars and leafworms.
Means to combat terrestrial insects include manual collection of pests and treatment of plants with specialized insecticides. It is more difficult if pelargonium was attacked by nematodes inhabiting the soil. In this case, the plant weakens, withers, its foliage becomes smaller, and on the roots there are noticeable nodules with cysts of the parasite. To prevent the pest of pelargonium, plants are planted only in the decontaminated soil. The same measure will help reduce the risk of infection of bushes with dangerous for pelargonium diseases of bacterial, viral and fungal nature.
Risk factors that impair pelargonium
In addition to poor quality soil, the spread of diseases contributes to:
- excessive density or poor soil;
- lack of light and air with excessive planting density;
- use of pesticides and herbicides;
- an acidic environment that does not allow the plant to receive the proper amount of nutrients and minerals;
- excess nitrogen in introduced fertilizers;
- damage to the root system and the green part of the pelargonium, for example, after transplantation.
All these factors weaken plants, which become a simple prey for both pests and for various diseases. What are the diseases in pelargonium, and how to deal with them?
Diseases of pelargonium: photos and descriptions
If violations of the conditions of cultivation and the appearance of pests of pelargonium react very sharply and quickly, the diseases at the first stages are hidden and for a long time do not make themselves felt.
Gray rot of Pelargonium
As a result of infection of plants with the fungus Botrytis cinerea leaves, the tips of the stems and inflorescences are covered with gray spots covered with peculiar fluff. In this case, the disease of pelargonium, as in the photo, is able to infect the flower at various stages of development, both in the flowering stage and during the rest period. In place of spots appear dead tissue areas, which on the leaves are clearly distinguishable by the brown concentric rings along the border of the fungus.
Fallen under the influence of the disease, as in the photo, pelargonium is dropped by buds, from which the fungus spores fall on the foliage and the surface of the soil. If you do not take urgent measures, the spread of gray rot does not end until the escape has decayed. The development of the disease contributes to high humidity and insufficient care.
Root rot or "black leg"
Decay of the lower part of the stem and part of the root system that provokes the spread of harmful fungus Pythium and Rhizoctonia from the side for the grower looks like:
- yellowing of the leaves of pelargonium;
- withering of shoots;
- weakening of the plant;
- the suspension of its growth.
Reproduction of fungi causes annular lesion of the stem at the level of the soil, on which, with high humidity, traces of gray or whitish plaque are visible. Fabrics quickly change the structure, become wet, peel, and all parts of the plant above the place of rotting lose the ability to receive moisture and nutrition.
Damaged roots are deformed, become brown, liquid and are necrotic. From illness, as in the photo, pelargonium often suffers at a young age. Particularly at risk of the disease are cuttings, which are in an excessively moist dense medium. The plant as a result of mushroom damage is rapidly weaker and dies.
Bacterial pelargonium disease or gummosis
Gummosis or bacterial spotting of leaves is accompanied not only by the change in the color of the foliage, but also by decay and wilt of the stems.
Pelargonium disease, as in the photo, becomes rapidly apparent and is determined by the yellowness of the leaves and brown spots between the veins, and is caused by the pathogenic bacteria Xanthomonas campestris. The first signs can be seen on the back of the leaf plates, and as the disease develops, the edges of the leaves wither, the veins turn black.
When the infection acquires a comprehensive character, the pelargonium plant fades, the shoots gradually die off. Blackening affects not part of the leaves, but whole stems. Unlike the "black leg" rot in this case is dry. The difficulty of diagnosing bacterial patchiness is that this pelargonium disease has common symptoms with plant injuries by insects.
Mosaic patchiness on the leaves of pelargonium
Different variants of mosaic disease are very common in pelargoniums, especially if plants are grown in crowded and high humidity.
This sometimes happens in the greenhouses of flower farms, from where flowering crops fall on the windowsills of ordinary lovers.
Rust of leaves of pelargonium
Brown or reddish traces of rust on the leaves of pelargonium are not traces of watering with poor-quality water, but the result of the activity of Puccinia pelargonii-zonalis fungi.
From the outside, the picture of the disease looks as if the foliage of the pelargonium turns yellow, but if you look at the back side, pads with maturing spores will be clearly distinguishable, which, having escaped to freedom, form the next wave infection. If the disease takes a systemic character, the leaves of the pelargonium turn yellow completely, then fall off, and the infection spreads to the stems.
Alternaria and cercosporosis
With both of these diseases, the pelargonium plants exhibit grayish or brown spots on the leaves, the tissue inside of which dries up, crackles and becomes discolored. Malicious mushrooms, the sources of the problem, settle on the back side of predominantly old foliage, but then the pelargonium disease, pictured, spreads higher up the stems. The seriousness of the disease is indicated by the lightening of the color of leaf blades and the loss of leaves.
Yellowness and clarification of foliage can also speak of swelling that occurs with excessive watering during periods of low temperature, cloudy weather and other conditions unfavorable for pelargonium growth.
With the development of chlorotic spots on the back of the leaf, the florist can notice their filling with moisture, then the formations become coarse, and their tissues acquire the properties of the cork. That is why the leaves of the pelargonium turn yellow and perish. The disease is particularly dangerous for the pellucid pelargonium and their hybrids.
How to deal with pelargonium diseases?
Already by description and photo it becomes clear how dangerous for plants the disease Pelargonium, but how to deal with them in the home or garden conditions?
All the main measures to combat bacterial and fungal diseases are based on competent care and prevention.
Having created comfortable conditions for pelargonium, it is possible to reliably protect them from any pests and parasitic microorganisms:
- The soil for pelargonium should not be dense and excessively moist.
- The content of nutrients in the soil must fully cover the needs of the plant and be balanced.
- Excess nitrogen in the soil is not the best way to affect the growth of pelargonium.
- The plant needs good drainage so that the water does not stagnate and does not provoke the development of root rot.
- Pelargoniums do not like top irrigation and moisture on the leaves.
- You can not tolerate the density of planting, otherwise the plants lack oxygen, the soil is not ventilated.
- For reproduction, only benign healthy material is taken.
- The soil under the bushes is regularly cleaned of plant residues, weeds, loosened and mulched.
If the pelargonium has signs of one or another disease, it is no longer worth limiting it to preventive measures. In this case, it is necessary to fight the diseases of pelargonium, using available fungicides and other special means.