Why do yellow leaves of cucumbers and how to deal with it?

Yellowing the leaves of cucumbers usually causes a lot of excitement among gardeners, because in this way the plant indicates a violation of growing conditions, some diseases and attacks of pests. An analysis of the yellowness and general condition of the plant, its inspection will help determine the cause of yellowing. In some cases, you have to act by the method of elimination.

It is necessary to separate the normal yellowing of the leaves and pathological. In the first case we are talking about old bushes, the lower leaves of which are yellow. In other words, the yellowing of the foliage of the plant signals the end of the growing season, a decrease in yield with the gradual cessation of the appearance of fruits. Yellowness can occur on the seedbed leaves of seedlings as a result of the appearance of new leaves.

However, it is easy to cope with such a nuisance - it is enough to remove excess ovaries and sprouts. Young yellowed leaves of seedlings - a sign that the plant is ready to transplant into the soil or greenhouse, it is closely in the container where it is grown.

With pathological yellowing, this process provokes a violation of the rules of agricultural engineering, as well as the defeat of a plant with diseases or attacks of insects. The latter are usually quite small. They settle on the back of the leaf, feeding on the plant sap and causing yellowing and drying of the leaf. The danger of this phenomenon lies in the fact that if you do not destroy the pest, the likelihood of the entire shrub drying out is high. Among the most dangerous insects for cucumbers are usually marked melon aphid. It is almost impossible to notice its appearance, it settles on the underside of the leaves. In this regard, very soon the aphid multiplies, and the bush begins to actively turn yellow and dry.

Another pest that prefers to settle down on the back of the leaf and deprive the plant of its vital juices is the spider mite. The first signs of his appearance are small cobwebs, which suddenly form on the cucumber ridge. The leaves turn yellow, dry and gradually curl. In the event of a serious injury, they are eaten dry shovels. First of all, the state of the foliage reflects a lack of nutrition - the lower foliage turns yellow. Using complex feeding usually helps solve the problem.

As a rule, the yellow border around the edges of the leaf, as well as the drying of the ovaries, indicates a lack of boron. Leaves with a deformed center indicate a deficiency of potassium, as a rule, they also have a yellow “rim”, the fruits of such plants become pear-shaped.

Excess, like lack of moisture can cause yellowing of cucumber leaves. The solution to the problem in this case is to adjust the watering and tear off the existing yellow leaves. Cucumber is a heat-loving culture that needs regular watering. In hot summer with a lack of precipitation is recommended to water the bushes every day or every other day. In some cases, it requires double watering in the morning and evening.

If the summer is warm, but not dry, then 2-3 waterings per week are sufficient. Choosing the mode of irrigation, you should focus on the condition of the soil, preventing it from drying out and cracking.

Before watering, if the ground is sufficiently dense, it should be loosened. In this case, you should act carefully, because the roots of this culture are in the surface layers of the soil. Regular loosening will avoid stagnant moisture and the development of rot. For watering you need to use warm or slightly cool water. Cold water is not absorbed by the root system and remains in the soil, causing overmoistening.The best irrigation system for culture is drip.

If it is impossible to organize such a system, it is recommended to dosed irrigation in trenches dug near the cucumber rows. In the hot summer to reduce the number of waterings and prevent the drying of the soil will help mulching.

When watering should also focus on the growth of the bush bush. Shoots up to a month require a liter of water per bush. This volume increases to 1.5 liters if the plant is 1-2 months old. If the plant is over 2 months to 3 months, up to 2 liters of water can be poured onto the bush. Older and branched bushes require at least 2.5-3 liters of water. The irrigation schedule is largely related to temperature.

The optimum temperature for culture is 24-26 degrees. When the temperature drops to +17 degrees and below the leaves start to turn yellow, and then dry and fall. When the temperature is too high, cucumbers also wither, losing the ability to create pollen.

You can not water the plant on a hot sunny day, it will cause foliage to burn. Yellow drying spots will appear on the leaves. Before deciding to change the schedule of irrigation is recommended to look at the nature of yellowness. If yellow spots appear on the leaves, this usually indicates increased humidity (excessive watering, thickening of plantings, lack of air movement in the greenhouse) or lack of trace elements.

Yellow tips and edges usually indicate excessive watering of the plant. If a similar situation is observed when growing cucumber seedlings, this may indicate that the capacity in which the vegetable is growing is too close. Yellowing of the middle of the leaves is usually caused by a lack of moisture in the soil and dry air.

Lack of sunlight also provokes yellowing of the leaves. In this case, we are talking about excessive thickening of plantings, because if you choose the wrong place for a bed, all the seedlings will have a stunted appearance. If yellow leaves appear as the bushes grow, then in most cases this indicates excessive planting density. In this case, you need to remove the yellow foliage and tie the lash. You can avoid this by not thickening the planting and tearing off the lower leaves on the seedlings.

In the soil there are always spores of fungi, which, under certain conditions, begin to actively develop. First of all, the lower leaves are exposed to the disease as they are closest to the ground. They begin to turn yellow and dry due to the fact that pathogenic formations rob them of all vital juices. Gradually, the disease spreads higher, covering the rest of the plant. One of the diseases characterized by the appearance of yellow foliage is powdery mildew.

First, cucumber leaves begin to turn yellow around the edges, and then become covered with a whitish bloom. There is also the so-called downy mildew or pernoporoz. As a rule, it is caused by excessive irrigation, the situation is aggravated by high humidity and greenhouse effect, as well as thickened plantings.

A sharp temperature drop can trigger the development of fusarium. The disease affects the root system, which interferes with the delivery of nutrients to the ground parts of the plant. Leaves and stems first turn yellow, fade, and then completely dry. Another disease that can develop due to a temperature violation (cold snap or watering with ice water) is root rot.

The mechanism of development here is the same - first the roots suffer, which is why the plant does not receive moisture and nutrients, therefore the above-ground part turns yellow and dies. The appearance of yellow or brown spots on the edges of the leaves, as well as on cucumber stems and fruits usually indicates the defeat of the bush with anthracnose.

Having considered the main causes of yellowness of leaves of cucumber bushes, we can conclude that in some cases the problem is caused by violations of agricultural practices. To eliminate the yellow spots and stop the shrinkage of the bush, it is enough to follow the rules of the agrotechnology of this crop - adjust the temperature, adjust the irrigation schedule and add the fertilizer to the plant. Cucumbers respond well to supplements, the main thing is to follow the schedule for applying organic and mineral fertilizers.

The first feeding is carried out after the formation of the first leaf on the seedlings, using for this purpose complex mineral fertilizers (ammofosku, azofosku) or bird droppings, mullein, herbal infusions.

The next feeding is in the period before flowering bushes. It is good at this time to make a solution of ash (1 liter of ash per 10 l of water), ammonia (20 g per 10 l of water) or potash (30 g per 10 l of water) saltpeter or superphosphate (40 g per 10 l of water). During active fruiting, a third feed will be required, which may consist of a solution of a cowshed with potassium sulfate (0.5 liters of cowshed, a tablespoon of potassium sulfate per 10 liters of water) or a solution of nitrophos (tablespoon of water per 10 liters).

Some gardeners put fertilizer "on the eye", not following the guidelines recommended by the manufacturer. Despite the fact that fertilizing is introduced regularly, the leaves continue to turn yellow. The reason is the insufficient amount of fertilizer applied, that is, the gardener introduces a smaller amount of them than the instructions require. An excess of fertilizing can also provoke yellowing and drying of the bush. For example, excess nitrogen burns the plant.

When fighting diseases, the plant should be treated by cutting off the affected leaves, after which you can proceed to the immediate treatment of the diseased shrub and the spraying of other plants. When signs of root rot are found, in most cases it is better to completely remove the bush and take it out of the site, and sanitize the growing place with copper sulphate. Root rot treatment is quite difficult, while it fairly quickly affects healthy bushes.

When the first signs of the disease appear or as prophylaxis, fungicides of biological origin can be used, and if their use does not work, use analogs of chemical genesis. To combat aphids and other pests, you can use biological products such as "Fitoverm", "Entobacterin", as well as more powerful chemicals "Fufanon", "Commodore". Get rid of the spider mite will help "Vertimek", "Kleschevit", "Oberon".

In most cases, gardeners prefer to use insecticides of a wide spectrum of action - “Aktellik”, “Konfidor”. When using the last death of pests occurs already after 3-5 hours after treatment. The effectiveness of the first agent lasts up to 10-14 days, the second - up to 30 days. They are not washed away by precipitation and are characterized by economical consumption.

These funds can be divided into those that act in a complex or are directed against a particular disease or pest. Experienced gardeners resort to folk remedies at the first sign of yellowness, since such methods of dealing with it are safer and less affecting the crop.

Among the most popular techniques can be identified.

• Spraying with a weak (1%) solution of potassium permanganate on the first signs of yellowing foliage.
• Strengthen the immune system of the plant and scare away the pest will allow onion infusion. To do this, 700 mg of onion peel should pour 10 liters of water and bring the composition to a boil. After that, remove from heat, insist overnight and strain. The resulting infusion to dilute with water in a ratio of 1: 4 and spray them with bushes. If there is excess infusion, it can be used for watering the beds.
• Whey can be considered a universal remedy in the fight against fungal diseases and pests. Preparing it is extremely simple - mix 1 part milk and 3 parts water. Use for spraying.

• Another means of combating a number of cucumber diseases is foliar treatment with a milk-soap solution, which is carried out every 10 days. For its preparation it is necessary to mix 10 liters of water and 1 l of milk, add 20 grams of soap (it is better to rub) and 30 drops of iodine. The mixture is suitable for processing not only adult bushes, but also seedlings after the appearance of a second leaf on it.
• High-quality dressing can be made using ash infusion. At 10 liters of water should take 30 tablespoons of ash and insist the composition of 48 hours. After that, filter and use for irrigation.
• Prevention of powdery mildew, as well as fertilizing is infusion of mullein. To prepare it, you need a fresh mullein (1 kg), pour 3 liters of water and leave for 3 days. Then strain the composition, diluted with water in a 1: 3 ratio (there should be more water) and apply for foliar feeding.

Insect pests can be controlled with the help of certain plants that have a pronounced smell. Many of them attract bees, wasps participating in pollination of cucumbers. Gourd aphid and spider mite do not tolerate the smell of marigolds, garlic. You can plant them nearby with a cucumber bed or use plant parts to prepare spraying solutions based on them.

Prevention of plant diseases is the annual change in the location of the cucumber beds. Returning to the previous place is possible only after 3-4 years It is not recommended to plant cucumbers on the beds where pumpkins or squashes grew. This significantly reduces the risk of developing culture-specific diseases. It is important to properly prepare the soil, if possible, doing it in the fall. Culture grows well on enriched and light, non-acidic soils. The best option - loamy or sandy land.

For a week and a half before planting, nitrogenous fertilizers must be applied; urea is ideal for this purpose. Immediately before planting the beds it is recommended to fertilize with the following composition: mix 100 grams of wood ash, a tablespoon of superphosphate and a teaspoon of urea. Compliance with the rules for making dressings, alternating root and foliar dressing and accurate dosage of fertilizer - this is one of the keys to a healthy shrub and the lack of yellowness on the leaves.

It is also important to avoid a large difference between day and night temperatures. If necessary, cover the cucumbers with a film or agrofabric. To debug the irrigation schedule, avoiding waterlogging or drying of the soil. To avoid the problem of stagnant moisture in the soil will help drip irrigation, regular loosening of the soil and watering the bushes with warm water.

The important point is that all the recommendations of the agricultural technician must be observed at the same time. It is impossible to fertilize a plant and at the same time not provide for it the desired temperature. Being in cold soil, the roots are not able to absorb the necessary minerals and, processing them, send them to the aboveground part of the plant. It turns out that no matter how much a gardener applies fertilizers, they are useless if he doesn’t cover the bushes for the night when the temperature drops.

It is important to observe an integrated approach in matters of fertilizer.As a rule, the introduction of nitrogen gives a quick and stunning result - the leaves turn green, and the plant from the stunted suddenly turns into a healthy shrub with a powerful green mass. However, an excess of nitrogen and the reluctance to understand which element is still in short supply leads to fattening of cucumbers. They increase the stems and leaves to the detriment of fruiting.

Diseases of culture is a consequence of improper care and the use of infected seed, planting it in the contaminated soil. Preventing the last 2 situations will allow disinfection of seed and soil before planting. A simple and effective way to do this is to stand the seeds in a weak hot solution of potassium permanganate and treat the soil with the same composition before planting. To strengthen the immune system and protect against diseases from the first days of life, sprouts can be periodically sprayed with milky soapy water. Avoiding yellowing of leaves helps periodic watering with water infused on rye bread.

Often the leaves turn yellow due to the large number of stepsons and ovaries, the plant simply does not have enough strength. To cope with the yellowness of the leaves will help pasynkovanie and tearing off excess ovaries. This, by the way, will help to get a better crop. Places of cuts can be covered with wood ash.

A few helpful tips from experienced gardeners will help you cope with cucumber problems.

• Spraying against diseases and pests should be done on both sides of the leaf. The procedure must be performed on a cloudy day or in the evening. If it has rained after spraying or less than 12-15 hours have passed since the procedure and precipitations have fallen, it is worth repeating the spraying.
• Many fungicides act on adult pests, so the treatment should be repeated 2-3 times every 5-8 days, because it is after this period that eggs are laid and larvae appear.
• When growing cucumbers in a greenhouse, yellowing of the leaves is usually associated with an increase in temperature in the structure. Quickly reduce the temperature allows ventilation of the greenhouse and spraying air in the structure.

For more on why the leaves of cucumbers turn yellow, see the next video.