Table of contents:
Video: Diseases And Pests Of Cucumber - We Protect Ourselves Without Chemistry
What cucumbers are sick with
- Powdery mildew and downy mildew
- White rot
- Melon aphid
- Spider mite
- Causes of poor growth and bitterness in cucumbers
In the previous article of the series "Organic farming: biological protection from pests and weeds" we talked about what methods and methods of fighting for the harvest are available in the arsenal of biological farming. Today let's talk in more detail about the diseases and pests of cucumber, consider the issues of prevention and control of them.
Cucumbers are considered one of the most ancient vegetable crops, which have been cultivated for about six thousand years. They came to us from India, where even now you can find wild cucumber-lianas, braiding the trunks of powerful trees.
This crop is quite whimsical to grow, especially given the current weather conditions, characterized by temperature fluctuations, frequent droughts, or, conversely, heavy rains. Therefore, in order to obtain high yields, it is necessary to study the characteristics of this crop well.
Cucumbers are very demanding on nutrition, they can grow directly on raw manure (except for pork). For normal health, they need a lot of water, the cucumber responds especially well to watering with impregnation or feeding from below. Partial shading from trees or tall plants (corn, sunflowers) protects the cucumber from the hot summer sun, in addition, these plants serve them as natural trellises, on which they weave with pleasure.
To obtain high yields, it is important to form the bush correctly. Formation will depend on the type of this culture. Cucumbers are pollinated and self-fertile hybrids (parthenocarpics), in which all female flowers turn into fruits on their own. Self-fertile cucumbers are best suited for growing in greenhouses. They are formed into one main stem, and all lateral processes are pinched after 3-4 leaves.
Pollinated varieties are formed differently. All female flowers in them, as a rule, are located on the branches of the second order, that is, on the lateral branches, and the main stem is covered with male flowers (barren flowers). Therefore, such bushes are formed in several lashes, and the main stem is pinched immediately above 4–5 leaves.
Unfortunately, today unstable weather conditions and increased solar activity negatively affect the growth of cucumber bushes and contribute to the development of dangerous fungal diseases that greatly affect the quantity and quality of the crop.
What cucumbers are sick with
Cucumbers are very susceptible to diseases such as powdery mildew, downy mildew (downy mildew), fusarium blight, white rot and black leg. All these diseases are caused by various fungi that attack the leaves, stems and roots of the plant.
Powdery mildew and downy mildew
Powdery mildew affects all types of melons (zucchini, squash, watermelon), but melons and cucumbers are especially affected in this case. This disease can be determined by a white or grayish bloom that forms on the stems and leaves of a plant, first in the form of separate spots, and then spreading over the entire surface. Leaves affected by the fungus turn brown and dry out, and if the disease progresses, whole lashes may die. Powdery mildew occurs when there is a sharp fluctuation in daily temperatures (during the day - hot, at night - cold). This disease is provoked by high humidity and cold dew.
Peronosporosis develops on the leaves of cucumbers in the form of light yellow oily spots, in the places of which a grayish-purple bloom subsequently forms - the affected leaves dry out. With the progression of the disease, only the stems of the cucumber remain green. Downy mildew spreads especially quickly in rainy weather at a temperature of 18-23 degrees and high humidity.
It should be noted that these fungal diseases most often develop when cucumbers are grown in greenhouses and greenhouses. Today, a large number of different drugs are presented on the pesticide market to combat these dangerous diseases. However, they all negatively affect the quality of the crop and the life of soil inhabitants. Therefore, gardeners who adhere to the principles of organic farming have developed biological means of combating various types of fungi.
A good effect is given by disinfecting seeds before sowing. To do this, they are heated in hot water (temperature 48-50 degrees) for 20-25 minutes. Then it is dipped in cold water for 2-3 minutes and dried.
When the first signs of powdery mildew are found, it is necessary to remove all affected leaves and spray the plant with mullein infusion, which is prepared according to the following recipe. One kilogram of mullein (can be fresh) is poured with three liters of water and defended for three days. The prepared solution is carefully treated with cucumber bushes. In this case, there is no need to save money, as such treatment not only kills the spores of powdery mildew and peronosporosis, but is also a wonderful top dressing. In the absence of a pure mullein, it can be replaced with the same amount of rotted hay or woody leaves (the infusion is also prepared). Processing must be carried out every week.
Fusarium is a fungal disease that is common, as a rule, in greenhouses, especially in spring ones without heating. Most plants affected by this disease look healthy before flowering. But already when entering the fruiting phase, they begin to fade and dry out. The first sign of fusarium disease is drooping cucumber tops during hot times of the day. If the disease progresses quickly, then the plants wither right before our eyes, the main root turns brown and dies, the base of the stem softens, cracks and dries up.
Given that it is problematic to determine fusarium in the early stages, it is almost impossible to cure diseased bushes. Therefore, prevention is the main weapon in the fight against this disease. It consists in disinfecting seeds as described above, maintaining constant temperature and humidity in greenhouses. Watering with warm water (20 degrees) and dusting the seeds with a biological product Trichodermin, which can also be applied to holes or peat pots when planting, will help prevent the disease.
A fairly common dangerous fungal disease that develops on all parts of the plant. Roots, stems, leaves and fruits can be affected. White rot is characterized by the presence of a dense white slimy coating, which contributes to wilting and drying of cucumber lashes. This plaque is especially dangerous because it can be transferred mechanically with the help of pieces of mycelium that have come off (on instruments and hands).
Like all other fungal diseases, white rot occurs and develops with high humidity and fluctuations in air temperature, as well as in the absence of good ventilation in greenhouses.
You can prevent the development of the disease by spraying the plants with mullein infusion. Processing with diluted dairy products also has a good effect. To do this, prepare the following solution: for 10 parts of water take 1 part of milk and add 5-10 drops of iodine. Cucumbers are thoroughly sprayed every 7-10 days. Instead of milk, you can use kefir or whey.
To prevent the occurrence of white rot and other fungal diseases, it is useful to sow trellis with cucumbers with crushed coal, chalk or ash.
Fungal disease affecting seedlings and young seedlings. The diseased plant turns yellow even in the cotyledonous leaf phase, while a constriction forms on the root collar, it turns brown and dries up. Diseased seedlings are oppressed, easily pulled out of the ground. High humidity and low air temperature contribute to the development of the disease.
To prevent the development of a black leg, it is necessary to avoid dense sowing of cucumbers in the greenhouse, it is necessary to carefully ventilate the film shelters and water the plants with warm water, to maintain the air temperature at 20 degrees. Practice shows that seedlings grown in peat pots practically do not get sick with a black leg. To disinfect the soil before planting cucumbers, the holes are etched with a solution of potassium permanganate at the rate of 5 g per 10 liters of water.
The main enemies of cucumbers in our dachas and vegetable gardens are insects such as aphids, spider mites and whiteflies. And the main weapon in the fight against these pests will be the creation of an ecological balance on the site, that is, the attraction of beneficial insects, birds, lizards and frogs, as well as the use of various herbal infusions and decoctions.
Aphids are a widespread pest that affects not only cucumbers, but most other vegetable crops. It is a very small insect (1.2–2.1 mm long), its color can vary from yellow to dark gray, the larvae are usually green or white. On cucumbers in open ground, aphids appear at the end of June; humid warm weather is considered favorable for its life.
Insect colonies are located on the underside of cucumber leaves, as well as on shoots and flowers. Aphids feed on plant sap, sucking it out, which contributes to wilting, yellowing and drying of cucumber lashes. The growth of cucumbers is delayed, and with a large accumulation of the pest, the plant may die. The danger of melon aphids lies not only in damage to the green parts of the vegetable crop, but also in the fact that it is a carrier of those dangerous fungal diseases of cucumber, which we talked about in the previous section.
An effective biological method to combat this pest is spraying cucumber trellises with various herbal infusions. These infusions can be prepared from garlic, dandelion, tansy, wormwood, and onion husks. A decoction of onion husks is prepared according to the following recipe: 400 grams of husks are poured with 10 liters of boiling water and infused for 2-3 days. Before processing, add laundry soap diluted in water (40 grams per bucket of solution). Cucumbers are processed several times with an interval of 5-7 days. If there are not very many aphids, then you can deal with them by simply washing the cucumbers with soapy water or a strong stream of clean water from a hose.
You can protect cucumber plantations from aphids and other insect pests by planting basil, nasturtium, garlic, marigolds, mint and other plants around them that will repel insects with their strong smell.
In the fight against aphids, it would be nice to enlist the support and help of entomophagous insects (lacewings, hoverflies). The main enemy for her are ladybugs, one individual of which can destroy up to 70 aphids per day.
A fairly common pest, both for greenhouses and for planting open ground. The body of the tick can be oval or oblong, 0.3–0.4 mm long. These insects and their larvae feed and live on the underside of cucumber leaves, braiding them with a thin web. Light spots first appear on the infected leaves, subsequently leading to wilting and drying.
Spraying cucumbers with water regularly in hot weather will help drive the pest away. An effective method of fighting a tick is the use of various herbal infusions and decoctions. For example, you can spray the bushes with infusion of wormwood, celandine, dandelion, as well as the peels of various citrus fruits. It is necessary to insist the grass with water for several days (until the specific smell disappears), and then dilute the infusion with clean water in a ratio of 1:20 - this is about 0.5–0.7 liters per bucket of water. It should be noted that such treatment, in order to avoid burns on cucumber leaves, must be carried out on dry plants before watering. Many different recipes for herbal infusions can be found in the book by Natalya Zhirmunskaya "A vegetable garden without chemistry."
This pest is a yellowish insect 1.5 mm long with two pairs of powdery white wings. Like all other pests, the whitefly settles on the lower parts of the leaves of the cucumber and feeds on the sap of the plant, which causes its oppression, drying out, and in some cases, death.
You can fight whiteflies by washing the cucumber lashes well with the pressure of water from a hose. Immediately after the pest is washed off, it is necessary to loosen the soil shallowly and add a bed of peat, sand or humus to the garden bed with a layer of 1–2 cm. In the fight against these insects, the treatment of cucumber trellises with various herbal infusions and sowing of cucumber leaves with ash or chopped charcoal helps.
Causes of poor growth and bitterness in cucumbers
Many gardeners often face a problem: cucumbers seem to be imposed, it seems that there are no diseases, but they grow poorly. There may be several reasons for this:
- Firstly, this is a lack of nutrition - cucumbers love well-fertilized soil, in the case of them, you do not need to be afraid to spread raw manure or droppings in the beds (except for pork), this will only benefit the plant.
- Secondly, a lack or excess of moisture can negatively affect the growth and development of a cucumber. It is important to note that in order to avoid the development of dangerous fungal diseases, it is recommended to water cucumbers with warm water.
- Third, violation of planting dates can be the reason for slow growth. Cucumbers are a thermophilic plant and they need to be planted when the soil is already warm enough. However, extreme heat can slow down the growth of this crop. It is best to shade the plants during the summer months.
Another important problem is the presence of excessive bitterness in cucumbers. This issue has not yet been well studied, and various versions of this phenomenon have been put forward. Some people believe that bitterness can be caused by sudden changes in temperature and insufficient watering. Others say that there are varieties that tend to accumulate cucurbitacin, the substance that makes the cucumber bitter. The cause of excessive bitterness can be unfertilized clay soil, a large amount of bright sunlight. In this case, there is room for experiment. As the saying goes, trial and error can be used to figure out which varieties and growing methods are best for your environment.
In any case, in order to obtain a high-quality environmentally friendly crop, it is necessary to use the opportunities that nature gives us. Study the properties of various plants, attract useful animals and insects to the garden, and you will get the opportunity to pamper your family with fresh and pickled crispy cucumbers clean from chemistry.