Why cucumber leaves turn yellow and what to do about it ⋆ 👨‍🌾 Farmer-online ⋆

8 problems with cucumbers and how to deal with them:

The reason for the yellowing of the leaves in cucumbers No. 1: lack of lighting

If the old lower leaves of cucumbers turn yellow, do not worry – for the cucumber “jungle” this is rather the norm. Plants grow a large green mass and light almost does not penetrate inside.

What to do: in general, you don’t have to worry. But for good development and fruiting, do not thicken the planting of cucumbers, tie up and form lashes, and regularly remove old yellowed leaves.

cucumber jungle in the open field

Cause of yellowing leaves in cucumbers No. 2: insufficient watering or waterlogging

What to do: focus on weather conditions and phases of plant development. Water for irrigation should be warm – + 23 … + 24 ºC. Before flowering and fruiting, the cucumber requires moderate humidity, and therefore the plants are watered 1-2 times a week (after 3-4 days).

With the beginning of the fruiting period, it is necessary to water the cucumbers more often, after 2-3 days. In the heat – daily, deeply wetting the ground, and in cool weather, the frequency and volume of watering should be reduced. Mulching helps keep moisture in the soil.

In rainy weather or excessive watering, cucumbers can be affected by rot.

watering cucumbers on leaves, overly thickened plantings

Cause of yellowing leaves in cucumbers No. 3: differences in night and day temperatures

Cucumbers stop growing at a temperature of about +10 ºC and die at negative temperatures.

What to do: if there is a danger of frost, cover the cucumbers with a film laid on arcs, or with non-woven material – lutrasil, spandbond, agrotex.

shelter cucumbers for the night

Cause of Yellowing Cucumber Leaves #4: Nutrient Deficiency

If the edges of the leaves of cucumbers turn yellow, a yellow border appears (marginal burn), and the leaf plates themselves are wrinkled, deformed – which means that the cucumbers do not have enough potassium (the pear-shaped fruit says the same).
If at the same time flowers are weakly tied or the ovaries dry out, brittle shoots, grow poorly – cucumbers are not enough wrinkle.
Young people turn yellow cucumber leaves, while the veins remain dark greenand (interveinal chlorosis) – cucumbers lack manganese or gland.
On old leaves between green veins appear yellow-green spots (mosaic) – cucumbers are missing magnesium.
Leaves (including veins) evenly turn palet (from light green to yellowish green), become smaller and thinner – disadvantage nitrogen.

What to do: spray cucumbers on the leaf with fertilizers containing the missing nutrient element, or with appropriate mineral solutions. Organic fertilizers also help. For example, with a lack of potassium, cucumbers are saved by an infusion of ash – 1 cup per 10 liters of water – spraying or watering under the root or a weak pink solution of potassium permanganate (spraying).

signs of magnesium and potassium deficiency in cucumbers

Cause of yellowing leaves in cucumbers No. 5 and the most dangerous: cucumber diseases

Peronosporosis (downy mildew) in cucumbers

The disease is determined by small numerous pale yellow, yellow-brown spots, which gradually increase in size, turn brown and dry, as well as by the “islands” of white mealy plaque. The disease develops with temperature changes, high humidity (more often in spring and in August-September).

What to do if cucumbers get sick with downy mildew: observe agricultural technology, do not overfeed with nitrogen fertilizers. At the first sign of the disease, spray with fungicides or “folk remedies”.

Powdery mildew on cucumbers

At the same time, a white (or slightly reddish) powdery coating appears on the upper side of the leaf.

signs of powdery mildew on cucumber leaves

What to do if cucumbers get sick with powdery mildew: as in the previous case, it is necessary to observe agricultural technology, and if a disease is detected, spray it with fungicides.

Root rot in cucumbers

If the leaves of cucumbers gradually wither, wither and dry out, check the roots of the plants – with a disease, the root neck turns brown, the roots rot.

What to do if cucumbers have root rot: as a preventive measure – steam the soil, pickle the seeds before sowing, do not thicken the plantings, water the plants with warm water. Sick cucumbers “rejuvenate”: the stem is bent to the ground, a little fertile soil is poured on top and rooted for 10-15 days.

Fusarium in cucumbers

The disease is common in greenhouses, especially with large temperature fluctuations in spring. It affects seedlings and adult plants. Before flowering, cucumber plants look healthy, and then, when the ovary appears, they begin to wither. The leaves turn yellow, the stems become thinner, dry out, then die off кorni and the whole plant dies.

What to do if cucumbers are sick with fusarium: disinfect the soil in the greenhouse, maintain optimal conditions (temperature, air humidity) and water the plants only with warm water. Severely damaged plants should be destroyed.

Anthracnose in cucumbers

Numerous rounded yellowish (brownish) spots appear on the edges of the leaves and on the stems. On the fruits – sunken spots, light brown, wet ulcers.

What to do if cucumbers are sick with anthracnose: carry out the whole range of preventive and therapeutic measures, including pre-sowing treatment of seeds with fungicides, high-quality balanced top dressing, removal of plant residues and diseased plants. Spray diseased plants with a 1% solution of Bordeaux mixture or 0,5% solution copper sulfate.

The reason for the yellowing of leaves in cucumbers No. 6: pests of cucumbers

Spider mite on cucumbers

Ticks predominantly live on the underside of leaves. They braid them with a thin web and suck out the juice. First, whitish dots form on the leaves, then they become larger, turning into spots. Eventually the leaves turn yellow and dry up.

What to do if a mites appear on cucumbers: spray with acaricides, paying special attention to the underside of the foliage. It is necessary to ventilate the greenhouse, periodically spray the leaves, and adjust the irrigation regime. Folk remedies are also used in the struggle.

Tobacco thrips on cucumbers

Small, about 1 mm in size, insects and light angular spots appear on the leaves. With the development of the lesion, the foliage turns brown and dries.

What to do if tobacco thrips is found on cucumbers: spray plants with insecticides. Preventive measures – regularly dig and loosen the soil, destroy weeds.

Whitefly on cucumbers

The whitefly infects cucumbers primarily in greenhouses, but some species can also live in open ground. Fuzzy yellowish spots appear on damaged leaves. They are gradually increasing. Leaves may curl slightly.

What to do if a whitefly is found in the greenhouse: preventive measures, treatment with insecticides and herbal infusions.

The reason for the yellowing of the leaves in cucumbers No. 7: cucumbers are overloaded with ovaries

In greenhouses and when growing cucumbers outdoors on a trellis, the leaves may turn yellow and the ovaries dry out if you do not form a plant. In greenhouses, cucumbers must be pinched, removing and pinching lateral shoots, and leaving no more than 20-25 ovaries at the same time on the entire plant.

Standard scheme for the formation of cucumbers

The lower 4-6 nodes of the main shoot are blinding. In the next 3 nodes, all side shoots are removed, leaving the ovaries. Further escape visually divided into three parts: at the nodes of the lower – pinch the side shoots into 1-2 sheets, the middle – into 2, the top – into 3. Then the shoot is wrapped around the trellis 1-2 times and pinched.

The reason for the yellowing of the leaves in cucumbers No. 8: cucumbers are poorly pollinated

What to do: when growing bee-pollinated varieties, provide good conditions for bees and bumblebees. In warm weather, keep the greenhouse open or ventilate it periodically. To attract pollinators, plant honey plants and dill near cucumbers. Spraying with a honey or sugar solution also helps (half a tablespoon of sugar or honey per liter of water). Among the drugs are boric acid (5 grams per 10 liters), boron-magnesium fertilizers, Bud, Ovary.

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