What to do if the leaves of cucumbers in the greenhouse turn yellow and how to prevent it

A change in the color of leaf blades on garden crops is a signal of a dysfunctional plant condition. The crop may be in jeopardy and the plant may die.

We will tell you what to do if the leaves of cucumbers in the greenhouse turn yellow, and how to avoid this problem.

Causes of yellowing of leaves in greenhouse cucumbers

Novice gardeners often make mistakes in plant care.... Inaccuracies in agricultural technology lead to a change in the color of the leaves of the crop.

Watering errors

Improper watering leads to wilting of leaves and requires urgent adjustment:

1. Dry soil in a greenhouse is the most common cause of wilting and yellowing on leaves. The optimal percentage of soil moisture for cucumbers is within 75-85%, that is, a lump of earth in your hands should not disintegrate when squeezed.
2. Insufficient moisture depth. With poor watering, the root system does not develop inward, which leads to disturbances in plant nutrition and yellowing of the lower leaves.
3. The yellowing of the leaves in cucumbers can be a reaction to insufficient or over-watering. With a high water content in the soil, especially in combination with cold weather, the roots of the plant begin to rot.
4. Watering with cold water. Comfortable water temperature for humidification is + 18… + 25 ° С.
5. Leaves irrigation in sunny weather. Avoid the ingress of water on the leaf plate, as the drops become lenses leading to tissue necrosis.

Temperature changes

Cucumbers are thermophilic. For their growth and development, air warmed up to + 20 ... + 24 ° C during the day and + 16 ... + 18 ° C at night.

Important! A temperature drop of more than 6 ° C is a severe stress for plants, to which they respond by yellowing the leaves.

A sharp drop in soil temperature to + 13 ... + 15 ° C - critical point: growth stops, the lashes turn yellow.

Lack of fertilizer

Fertilizers compensate for the lack of nutrients in soil. The lack of elements necessary for cucumbers is manifested by such signs:

1. Nitrogen... The lack of a trace element affects the development of the entire plant as a whole: at first, the veins brighten, then the leaves become faded green, turn yellow, become smaller, the lashes become thinner. First of all, nitrogen starvation appears on older leaves. Often nitrogen deficiency in the greenhouse occurs when planting cucumbers after tomatoes.
2. Phosphorus affects the yellowing of leaves indirectly: its deficiency leads to poor absorption of nitrogen by the root system.
3. Potassium maintains water balance, improves cold resistance and disease resistance. Its deficiency is manifested as follows: initial yellowing of the leaf edge, its browning and dying off, while the veins seem to be pressed inward.
4. Calcium... With its lack, white spots are observed at the edges and between the veins of the leaves, later only the main veins remain green.
5. Magnesium... Yellow spots (chlorosis) appear on older leaves between the veins.
6. Iron necessary for plants to form chlorophyll. The deficiency is manifested by a combination of yellow spots with bright green streaks.
7. Copper... Yellowing of young leaves testifies to its lack.

Insufficient lighting

In the case of thickening of plantings or improper formation of a cucumber bush on a trellis in a greenhouse, the lower leaves receive less light, which leads to their yellowing and death.

Diseases

Diseases dangerous for cucumbers:

1. Root rot... One of the most common causes of yellowing is the result of significant temperature fluctuations during the day and night.
2. With bacteriosis of cucumbers (or angular spot) small yellow spots appear on the cotyledons, then they turn brown and begin to wet, which leads to necrosis.
3. Peronosporosis (downy mildew). With this fungal disease in the interveinal space, separate small yellow spots of an acute-angled shape with clearly defined edges appear on the front side of the leaf. Over time, they turn brown-brown, the edges of the leaves are bent upward.
4. Anthracnose... It affects all parts of the plant. The browning and drying of the leaves is preceded by the appearance of small yellowish-green spots, gradually increasing in size and merging with each other. Then holes are formed in these places.

Pests

Pests that infect cucumbers in the greenhouse:

1. Aphid settles on the underside of leaves and sucks out juices from plants.
2. Yellow, wilting leaves with a cobweb signal the need to check plants for spider mite... In the dry air of greenhouses, in the absence of ultraviolet radiation, the insect quickly multiplies on cucumbers. If you don't fight it, the whip will soon die.

Aging plants

Yellowing of the lower leaves on the plant towards the end of summer - the natural state of its vegetative developmentwhen the plant's life cycle comes to an end.

Is it dangerous for the harvest

Leaves for any plant are a source of respiration and energy, photosynthesis and metabolism take place in them.With significant damage to the leaf apparatus, the plant cannot fully develop. and give a good harvest.

What to do

The task of any gardener is to find methods to prevent yellowing and death of the plant, to preserve the harvest.

Fertilizers

The choice of fertilizers depends on the deficiency of minerals in the soil... But an inexperienced summer resident may incorrectly determine what kind of fertilizer and how much is needed for cucumbers. Overdose can aggravate the situation.

Council. Apply fertilizer under two or three bushes. If after four days the situation changes for the better, then the fertilizer and the proportions of its dilution have been chosen correctly. You can start feeding the rest of the plants.

Recommendations for fertilizing:

• the lack of nitrogen is replenished by fertilizing with manure (in a ratio of 1:10), herbal fertilizer (1: 5), urea or ammonium nitrate (2 tablespoons per 10 liters of water);
• if necessary, add phosphorus to the soil, use "Superphosphate" (3 tablespoons per 10 liters of water);
• potassium deficiency is replenished with a chlorine-free potassium fertilizer (3 tablespoons per 10 liters of water) or a solution of wood ash (for 10 liters of water - 500 g);
• with a lack of magnesium, dolomite is diluted (1 glass per 10 liters of water);
• the need for copper, iron, zinc is replenished with chelated forms of these microelements.

Chemicals

When cucumbers are infected with fungal or bacterial diseases, often settling in greenhouses, cannot do without treatment with chemicals.

Attention! Consider the amount of time it takes to remove the drug from the plant. Possible post-processing time to harvest can range from 3 to 30 days.

The following fungicides are used against fungal diseases of cucumbers: "Previkur", "Ridomil", "Topaz", "Bravo", "Oksikhom", "Aviksil" and others.

The often recommended Bordeaux liquid is used for preventive purposes only.

Broad-spectrum insecticides work against aphids: "Inta-Vir", "Aktara", "Confidor", "Fitoverm", "Fufanon".

Acaricides will help get rid of spider mites ("Akarin", "Agravertin", "Floromite") and less dangerous biological preparations: "Vertimek", "Kleschevit", "Fitoverm".

It is important to observe the frequency of application of drugs in order to avoid the resistance of the disease / pest to the drug.

Traditional methods

As an antifungal agent used baking soda solution (1 tbsp. L. For 1 bucket of water).

Disinfectant & Nutrient Blends:

• based on milk or kefir (1 liter per 10 liters of water) with the addition of 40 drops of iodine;
• infusion of onion peel;
• infusion of bread and iodine.

For insects, cucumbers are sprayed with infusion tobacco, celandine or horse sorrel, hot pepper with soapy water.

Agrotechnical techniques

The easiest way to eliminate the causes of yellowing of cucumber leaves is if they were the result of improper plant care:

1. Competent watering - irrigation in the morning or evening hours 3-4 times a week with water + 20 ... + 25 ° С. Drying of the top soil layer to a depth of 3-4 cm signals the need for urgent watering.
2. Using mulch that will trap moisture and heat in the soil and provide additional nutrition to the plants.
3. During cold snaps, it is recommended to close the greenhouse doors, in the heat - to ventilate the structure (this will prevent condensation from accumulating).
4. Trimming overgrown cucumber vines to improve lighting.

Preventive measures

To prevent the problem of yellowing and wilting of leaves cucumbers in the greenhouse, follow the tips:

1. Observe the crop rotation. It is not recommended to plant cucumbers after pumpkin seeds or for several years in a row in one place.
2. Treat greenhouse walls and soil with disinfecting and antifungal agents.
3. Choose varieties of cucumbers that are resistant to pests and diseases that have arisen on your land.
4. Decontaminate seeds before planting.
5. Organize a drip irrigation system.
6. Apply organic or mineral fertilizers to the soil when digging.
7. During the growing season, carry out mandatory feeding.
8. For optimal growth conditions of cucumber lashes and ease of care for them, observe the density of planting seedlings.

Advice and feedback from experienced gardeners

Summer residents share their experience in combating yellowing of leaves on cucumbers.

Vera, Pavlovsk: “I have used different methods in the past. Stopped on iodine, serum, herbal infusion. I do not loosen the soil around the roots within a radius of 10 cm, and in the second half of the season I only add soil to the roots once a week after the next watering. Always with the harvest! "

Tatiana, s. Red: “The weather this summer is awful. A large dark barrel of water can be placed inside the greenhouse. It collects heat from the sun during the day and warms the air at night. I heard this advice from a neighbor. I asked my husband, he brought me two iron cans. I put it at the entrance and exit of the greenhouse. The cucumbers stopped turning yellow and started growing ".

Elena, Orsk: “Last year, my cucumbers almost died because of a spider mite. Suddenly the leaves began to turn yellow, and then dry. I noticed that there is a cobweb on the sheet and there is some kind of movement. I read about Fitoverm and decided that I could try to sprinkle it, given that the greens could be picked in three days. The tick disappeared immediately, did not even wait for the second treatment ".

Conclusion

Initially, it is important to determine the cause of the yellowing of the leaves on the cucumbers in the greenhouse and then act depending on it. This is the use of fertilizers to replenish missing micronutrients, chemical or folk methods of combating diseases and insects, the use of agrotechnical techniques to create favorable conditions for the growth of cucumbers.