What are the diseases and pests of cucumbers, how to deal with them
Here you can learn about which diseases of cucumbers cause the most damage to plants and how to protect plants from infections. After reviewing the photo and description of cucumber diseases, you will be able to recognize the disease in a timely manner and take the necessary control measures.
Diseases of cucumbers in the greenhouse in the photo
Downy mildew (downy mildew)... The widespread fungal disease of cucumbers, which is the main cause of premature death of summer crops of cucumbers, also affects cucumbers in greenhouses.
On the affected leaves, round or angular yellow spots appear, on the underside of which a grayish-purple bloom of conidial sporulation of the fungus develops.
As you can see in the photo, with this disease of cucumbers, the affected tissue becomes fragile and easily crumbles, the leaves wrinkle and fall off:
In conditions of closed ground with high humidity, leaves affected by downy mildew rot.
During the summer, the fungus spreads by conidia, and then spores form in the affected tissues, in the form of which it hibernates. The development of the disease is facilitated by fog, dew and moderate temperatures (+16 ... + 22 ° С). The source of the disease is the remains of diseased plants.
To combat this disease of cucumbers, it is necessary to observe the rotation of crops, carefully remove and destroy plant debris. In greenhouses - it is necessary to maintain the optimum temperature (above +24 ° C) and humidity (within 80-90%).
For the prevention of peronosporosis (downy mildew) use "Profit Gold". When the first signs of the disease appear before fruiting, cucumbers are sprayed with one of the copper-containing preparations (Bordeaux liquid, "Abiga Peak", "Oxyhom", "Hom", "Ordan", etc.). Repeated treatments in case of renewal of the disease during the fruiting period are carried out with biological preparations "Fitosporin-M", "Alirin-B". Preparations for protection against downy mildew must be alternated. As you can see, it is not so difficult to fight this disease, the main thing is to recognize the disease in time and prevent its spread.
Powdery mildew in the photo. Fungal disease of cucumbers
Powdery mildew. Also fungal disease. Initially, the disease appears on the upper side of the leaves in the form of individual white powdery specks, covered with a bloom of the mycelium of the pathogen. The spots increase; merging, they cover the entire upper side of the leaf.
With this disease of cucumbers in open ground and greenhouses, powdery bloom appears on the underside of the leaves, as well as on the petioles. Severely affected leaves dry out. Indoors, the disease is also noted on fruits.
During the season, the pathogen of powdery mildew is spread by spores with an incubation period of 3-4 days. In winter, the fungus remains on infected post-harvest residues.
The disease can reduce the yield in the open field by 30%, and in greenhouses by 60%.
When treating this disease, cucumbers can be sprayed with Topaz, and during the harvest season - with gray colloid, Tiovit Jet, Fitosporin-M or Alirin-B when the first signs of powdery mildew appear, and then at intervals of 7 10 days.
Cladosporium (olive brown spot). A fungal disease that develops on cucumbers everywhere in open and closed ground. Mostly the fruits of cucumbers are affected, but sometimes leaves and stems get sick. The first signs of cladosporium on fruits are small watery spots that quickly increase in size, reaching 5 mm in diameter; the skin of the fruit cracks, rapidly hardening gelatinous drops appear on the surface of the spot. At high air humidity, the spots become covered with a black-green velvety bloom.
Pay attention to the photo - with this disease of cucumbers in open ground and in a greenhouse, diseased fruits are bent:
Scattered small brown spots surrounded by a yellowish border appear on leaves affected by olive brown spot at the beginning of fruiting. The raid on them is dim, weak. On old leaves, the affected tissue falls out. On the stems, the disease manifests itself in the form of dry ulcers.
The causative agent of the disease develops at wide ranges of temperature (+5 ... + 30 ° С) and relative humidity (from 35 to 100%), but the strong development of the disease is facilitated by a decrease in temperature at night to +16 ... + 18 ° С with relative air humidity over 85%.
Control measures for olive brown spot include maintaining optimal temperature and humidity conditions. If necessary, spraying plants with copper-containing preparations, as well as against peronosporosis.
These photos show the diseases of cucumbers and how to treat them:
Root rot. The disease mainly affects cucumbers in greenhouses, and it also occurs on plants in the open field. Root rot disease is usually preceded by weakening of plants under the influence of unfavorable external conditions.
On cucumbers in greenhouses, the disease manifests itself in the fact that the leaves, starting from the lower ones, gradually turn yellow. Gradually, the plants wither. The browning of the bark is noticeable on the lower part of the stem and roots.
Look at the photo - with this disease, the stem of cucumbers in greenhouses is milled.
The disease usually occurs as a result of a decrease in soil temperature or an excessively high concentration of minerals, as well as when watering with cold water. Lowering the air temperature in greenhouses to +17 ... + 18 ° С contributes to the development of the disease.
The disease is more severe when sunny weather follows a long period of cloudy weather. Focal rot is often observed in areas where the greenhouse roof is leaking.
Similar signs of the disease are observed in plants outdoors, often after watering or heavy rain. First, the leaves turn slightly yellow and stick. At the same time, the stem and roots have an outwardly healthy appearance, but there are no root hairs on the roots.
Here you can see a selection of photos of diseases and pests of cucumbers in greenhouses and open field:
Fusarium wilting. On the affected seedlings, the cotyledons wither or the lower part of the stem rots, as a result of which there is a massive death of seedlings. On adult plants, individual lashes wither first, and then the whole plant dies, often having a green color.
The causative agent of fusarium wilting persists for a long time in the soil; it can also be found in infected seeds. It penetrates into the plant through young cells of root tissues, root hairs, grows in the tissue of the root collar; through wounds formed on individual lashes during pinching and other work. Inside plants, the mycelium of the fungus spreads mainly through tissue cells and blood vessels.
In the fight against root rot and fusarium wilt, strict adherence to crop rotation, careful collection and removal of plant residues is necessary. Application of organic and mineral fertilizers, plant feeding during the growing season, destruction of the soil crust - after each watering, especially in the first period of growth.
Phosphorus-potassium fertilizers and wood ash reduce the intensity of the development of fusarium wilting.
It is also necessary to disinfect the seeds by soaking them in Fitosporin solution for 1-2 hours before sowing. When seedlings appear and during the growing season, water the plants with "Glyokladin".
The warmth and high humidity in the greenhouse is a dangerous combination for juicy stems and fruits, meaning disease-causing fungal spores.
Gray rot (botrytis). Cucumbers are mainly affected by it in greenhouses. The disease develops on various organs of the plant. This fungal disease causes especially significant damage, affecting fruits.
To prevent large losses from gray rot, possibly by observing the alternation of crops and maintaining the optimal temperature (at least +18 C) and air humidity (within 90%) in the greenhouse. It is necessary to remove rotten fruits and severely affected plants from it.
Angular spotting (bacteriosis). The further development of the disease will be restrained by the biological preparation "Gamair".
To protect cucumbers from diseases and pests, you should not:
- Overfeed plants with nitrogen to keep stems and leaves soft and thin.
- Planting plants too densely: this makes it difficult for air to reach them. Damp stagnant air and tightness contribute to the development of disease.
- Create a stuffy, stuffy atmosphere in greenhouses and greenhouses. Avoid cold drafts in winter. When ventilating, open windows on the leeward side.
- To injure plants and fruits, this opens up easy access to pathogens.
- Leave cucumber fruits affected by diseases and pests on the plant - destroy them immediately.
Pests of cucumbers in the open ground and greenhouse, measures to combat them
Aphids are one of the most common and dangerous pests in cucumbers. It appears on young plants (at the stage of 3-4 leaves), therefore, the harm from it is especially noticeable. Leaves inhabited by aphids shrivel and curl, shoot growth stops, the plant dies. With the later development of aphids under the influence of the pest, the curvature of the shoots, drying of the flowers and ovaries are observed. These outdoor cucumber pests secrete polluting plants with copious, sticky, sweet excrement, on which sooty mushrooms settle, which also aggravates the condition of the cucumber.
Aphids are quite large, up to 2 mm, clearly visible to the naked eye, black in mass. During the season, it develops in 15-20 generations (the hatching of more and more pests is almost constantly taking place). Moderate and humid weather contributes to the rapid reproduction of aphids.
Adult aphids overwinter on the leaves of weeds, most often on a shepherd's bag. In the spring they feed on weeds, later they fly to cucumbers. Aphid females are viviparous, their average fertility is 25-60 larvae.
In the fight against aphids, as soon as it appears on the plants and before the cucumbers begin to bear fruit, apply spraying with one of the preparations (Iskra-M, Iskra Zolotaya, Iskra Double Effect, Confidor or Commander). With repeated spraying, the preparations must be alternated so that the pest does not get used to them.
During the fruiting period, only biological preparations with a waiting period of 1-2 days ("Iskra Bio", "Akarin", "Fitoverm", "Agravertin") can be used against aphids.
The spider mite also causes severe damage to cucumber plants. A tick appears especially often if the air in the greenhouse is dry, this pest of cucumbers leaves light yellow spots in the form of pricks visible to the naked eye on the underside of the leaves. If such spots are found, the plants are sprayed with garden sulfur or colloidal sulfur, you can use "Tiovit Jet". Spraying is repeated after 7-8 days. When using sulfur-containing preparations, do not water the plants with sprinkling, so as not to wash them off the leaves. Sulfur preparations will also help cucumbers in the open field, where a large number of spider mites colonize plants in July, August, when the heat is more than +30 ° C with a low relative humidity of 35-45%.
Among biological preparations against spider mites, "Bitoxibacillin" and biological preparations recommended against aphids give a good effect.
A radish planted between cucumbers and tomatoes scares off leaf beetles and spider mites.
Minerals are pests that infect cucumbers in the open field during the fruiting period. With a large number of pests, use biological preparations as against aphids.
Cucumbers, like tomatoes, suffer from whitefly in open and closed ground.
These photos show the pests of cucumbers that affect plants in the open field and in the greenhouse: