What diseases of cucumber seedlings exist: photos and descriptions
It would seem that nothing could be easier - growing cucumbers in the country. However, any business has its own nuances, and a good harvest requires effort. Fragile seedlings are threatened by dozens of diseases, many of which lead to the death of all plantings, make the fruits inedible and damage the soil for a long time.
In this article we will talk in detail about typical diseases of cucumber seedlings, their symptoms and treatment methods.
The main signs of diseases of cucumber seedlings
Many diseases affect plants so quickly and extensively that they can no longer be saved. To avoid this, you should foresee possible dangers in advance and recognize the enemy by sight. Let's look at the first signs of disease.
Yellow veins on leaves
Appear along the edges and entire surface of the leaves. Such symptoms signal a viral infection of the plant.
The seedlings fall and wither
If drooping seedlings are found, take a closer look to see if the stems are thinning. Cucumber seedlings may fall due to fungal infection.
Curling leaves
Wilting of seedlings often occurs with curling of leaves. This is the result of a lack of moisture or microelements in the soil.
Delay in seedling development
This symptom appears when the root dies and in the absence of visible causes. Subsequently, the plant dies.
What are the diseases of seedlings and their descriptions?
There are about 20 types of common diseases of cucumber seedlings. Improper care, insufficient soil nutrition and many other factors contribute to fungal infections, bacterial and viral infections.
Diseases of fungal origin
Diseases caused by fungi most often affect cucumber seedlings. They are caused by fungi of the genus Pythium Pseudoperonospora, Fusarium, oxysporum f. nveum, Thielaviopsis basicola, Erysiphe cichoracearum, Pythium.
Powdery mildew
A disease that mostly affects greenhouse cucumbers. It begins with the appearance of a white coating on the underside of the leaves. Then the leaves change shape, the cucumber fruits begin to taste bitter, and the plant itself withers.
Downy mildew (downy mildew)
Affects stems and leaves. Oil spots appear first, which later turn brown and the leaves dry out.
Root rot
The disease can be noticed after planting the seedlings. Symptoms - limp leaves, yellowed stems, frozen ovaries.
White rot (sclerotinia)
The disease manifests itself in foci of infection with white mycelium, which later turns black. The stems have a watery appearance.
Gray rot
First symptom – the appearance of brown, blurry, slippery spots on the leaves. Subsequently, the fruits become covered with spots. Cucumbers become watery and soft, and gray fluff (spores) appears on them.
Black rot (ascochyta blight)
Appears during fruiting or during stem formation. It begins with the appearance of gray watery spots on the stem. Then the leaves are affected, first along the edges and then over the entire surface.
Black mold
This disease affects all above-ground parts of the plant. Small brown spots of various shapes appear on the leaves, then they merge and turn into necrotic spots, around which brown rims appear. The leaves die, and the remaining parts of the seedlings become covered with cobwebs.
Anthracnose (scarden)
Disease pursues cucumbers throughout the entire growing season.Yellow or brown spots appear on the edges of the lower leaves and between the veins. The leaves turn yellow, their functions are impaired, and then the stems begin to suffer. The fungus affects the fetal tissue to a depth of 3-4 mm.
Cladosporiosis (olive spot)
One of the most dangerous diseases that affects weakened plants. The fruits are covered with brown, wet sores, after which they cannot be eaten.
Rhizoctoniosis
This fungus infects the cotyledon leaves near the root collars by forming small yellow-orange spots. Fruits and leaves with petioles that touch the soil are infected. Spots also appear on the tops of the fruits. The plant dies at the seedling stage.
Tracheomycosis
Cucumber wilt disease is divided into fusarium and verticillium wilt.
- Fusarium. An extremely dangerous disease. Manifested by the withering of cucumber vines. A fungal infection affects the vessels of the plant. When cutting a stem or leaf, you can see that they have a brown tint. The plant rots from the base of the root, the stem becomes thinner, darkens, the leaves turn yellow;
- Verticillium. Also manifested by wilting of cucumbers. It begins with one-sided wilting of the leaves, then the entire plant withers.
Alternaria (dry spotting)
Disease of greenhouse cucumbers. First, dry brown spots of a convex shape form on the lower leaves, then they merge into large formations. Gradually the leaf blades die off. The disease does not spread to the stems.
Important! To reduce the risk of fungal infections, prepare the soil properly. Signs of healthy soil are thorough disinfection and full breathability.
Diseases of bacterial origin
Both in the greenhouse and in the open ground, cucumbers can be affected by bacterial infections.Diseases are transmitted by seeds and plant debris. Wind, rain and insect pests can also transmit the infection.
Angular spotting of leaf blades (bacteriosis)
The causative agent is a bacterium of the pseudomonad family of the actinomycetes class. It is found in soil and water, sometimes in the human body and food. The toxin released by bacteria affects the epidermis of living organisms. In cucumbers this is the leaf cover. Brown spots form on the leaves, then death occurs. Up to 90% of leaves are affected by the disease; stems and fruits are partially affected.
The photo shows leaves affected by bacteriosis.
Diseases of viral origin
Viral diseases of cucumbers affect plants at the cellular level. The causative agents are Cucumis virus 2A, Cucumber mosaic cucumovirus (CMV), ICDMO, Tobacco necrosis virus. Viral diseases include different types of mosaics. More often, the disease affects cucumbers in greenhouses.
White mosaic
The first symptom is blurry yellow-white spots in the shape of stars or rings near the leaf veins. Next, the color of the spots changes to greenish-white, then the entire leaf becomes white.
Mosaic green
The disease is characterized by the appearance of light green spots and deformation of leaves and fruits. The virus penetrates the stems and root system and destroys plants.
Ordinary mosaic
Appears on young seedlings. The leaves wrinkle and become covered with mosaic spots of a light green hue. The edges of the leaves curl and the plant stops growing.
Viral necrosis
It appears on the cotyledons as pale yellow necrotic spots in a circle of green zone. There is wilting and death of leaves, deformation of fruits, on which spots also form.
Causes of cucumber diseases
Knowing all the diseases of cucumbers is only half the battle. For successful treatment it is necessary to know the reasons that cause them.
Improper care
Cucumber loves warmth. Violation of the temperature regime is fraught with various plant diseases. The optimal temperature for cucumber is 20-25°C. At elevated temperatures or temperature changes, seedlings become vulnerable to diseases, especially fungal ones. When growing cucumbers in a greenhouse, you need to create optimal temperature conditions for them.
Another important indicator is the level of soil moisture. High humidity provokes bacterial diseases of cucumbers.
At low humidity, the plant loses its immunity, which also contributes to the development of diseases. Humidity is easier to monitor with any growing method. It is enough to control watering. To determine the indicators, there is a special moisture meter.
Important! The optimal level of soil moisture is 70-80%.
Sources of diseases can be weeds and last year's plant debris. Be sure to get rid of them immediately upon discovery. Seed disinfection is also required. They can be infected with pathogens.
Lack of nutrition
It is not enough to create favorable conditions for the growth of cucumbers; they must be fed with fertilizers, the lack of which directly affects the yield.
Potassium is responsible for fruit formation. The first sign of potassium deficiency is yellowing and falling leaves. Subsequently, the fruits acquire a hook-shaped shape. At this stage, the plant can no longer be helped.
With nitrogen deficiency, cucumbers stop growing. The fruits remain small and yellowish and are shaped like carrots.
If there is a lack of phosphorus, the plant grows large, but the fruits remain small and lose their taste.
It is also necessary to feed the plant with microelements; without this, it will not be possible to grow good and tasty cucumbers.
Insect pests
The most likely pests of seedlings:
- spider mites suck sap from leaves;
- whitefly - due to the abundance of its larvae, the leaves wither and become covered with a gray coating;
- slugs eat any parts of the plant;
- ants chew through roots;
- melon aphids feed on the sap of leaves and stems.
Methods for treating seedling diseases
Like other garden crops, cucumbers are treated for diseases using biological, chemical and folk remedies.
Folk remedies
- 2 g of potassium permanganate is diluted in 10 liters of water and sprayed on the plants.
- 30 g of crushed garlic is poured into 1 liter of water and left in a cool, dark place. Before spraying, the tincture is diluted in 9 liters of water.
- 1 liter of whey is diluted in 10 liters of water and the plants are treated.
- 60 ml of 3% perhydrol is diluted in 3 liters of water and sprayed.
- Spray the tobacco mixture onto the moistened leaves.
Chemicals
Chemicals include fungicides and insecticides. Fungicides are used to control diseases, insecticides destroy harmful insects. Treatment with chemicals is carried out during the growing season of cucumbers, but no later than 21 days before the start of harvest. Use chemicals strictly according to instructions and follow safety precautions.
Sandofan M8, Acrobat MC, Oksikhom, and Strobi have proven themselves to be the best fungicides.
Among the effective insecticides you can choose “Aktellik”, “Kuproksat”, “Fufanon”, “Confidor”, “Fitolavin 300”.
Biological agents
Biological products are added to the soil to protect cucumbers from diseases. As they spread in the soil, they release substances that inhibit the development of diseases.Such preparations have proven themselves to be a reliable means for the prevention and treatment of diseases, especially root rot.
The most effective means: “Alirin B”, “Glyokladin”, “Gamair”, “Vitollan SP”, “Trichotsin SP”.
Important! Cucumbers most often get sick at the flowering stage, so it is better to carry out preventive treatment before the flowers appear.
Basic rules for caring for seedlings and preventing diseases
The key to a good harvest is proper care of seedlings. After planting in the ground, healthy seedlings have strong root and above-ground systems and are less susceptible to disease.
Top dressing
Seedlings are fertilized at least twice. The first time is two weeks after germination, then when the second true leaf grows.
2-3 days before planting in the ground, the seedlings are fed again.
Fertilizers are applied in the morning along with watering strictly at the root. They should not get on the stem and leaves.
The most commonly used fertilizers are “Breadwinner”, “Fertility”, sodium and potassium humate, “Nitrophoska”.
Picking
While the seedlings are small, they develop well in a common container. As the root system develops, each plant needs more space. To do this, they carry out picking - transplanting the babies into separate containers with soil mixture. It is carried out in the early stages of growth, when the cotyledon leaves have fully opened and true leaves have appeared. Small plastic cups are suitable as containers. Drainage holes are made in them and filled with substrate a day before the dive.
Before transplanting, the seedlings are watered generously and removed one at a time with a small lump of earth using a small spatula.
Recesses are made in containers and seedlings are placed in them to a depth of up to the cotyledon leaves.The leaves should not touch the soil, otherwise the seedlings may rot.
Important! The picking is carried out extremely carefully so as not to damage the thin roots of the seedlings.
Conclusion
Despite all its advantages, cucumber is a crop that is vulnerable to fungal, bacterial and viral diseases. To avoid putting plants at risk, follow the rules of care, learn to recognize diseases at the first signs and know the optimal methods of treatment. Then the grown crop will be able to delight you with its abundance and tasty fruits.