Cucumbers get yellow leaves: what to do?

When the first yellow leaves appear on your cucumber plants, you should immediately start looking for the cause. This can be harmless but also a serious infection or a pest infestation. If you react too late, your plant may no longer be salvageable and the hoped-for and desired harvest will not come about.

Do greenhouse cucumbers also have yellow leaves?

Your cucumbers can also develop yellow leaves in the greenhouse. The causes are similar to outdoor cucumbers. However, the room climate or care errors are particularly common reasons. Too dry air and/or drafts easily lead to an infestation with spider mites. Make sure that the humidity is sufficiently high and that air circulation is constant. When watering, avoid waterlogging and do not plant your cucumbers too close together.

What causes yellow leaves?

• nutrient deficiency
• dryness
• Fungal infections (cucumber wilt, Verticillium wilt, powdery and downy mildew)
• leaf spot disease
• cucumber mosaic virus
• aphids
• spider mites
• draft

nutrient deficiency

Cucumbers are among the so-called heavy feeders. These are vegetables that have a very high nutrient requirement. It is best to add a good portion of mature compost or rotted cattle or horse manure to the soil when planting. For a faster effect, you can mix the compost with horn shavings. Alternatively, use a good organic complete fertilizer or a special cucumber fertilizer according to the manufacturer's instructions. A second fertilization in July is recommended unless you have given slow-release fertilizer.

dryness

For good growth and juicy fruits, your cucumber plants not only need plenty of nutrients but also a lot of water. If this is missing, the cucumbers become slightly bitter. Water your plants regularly, preferably every morning. Use lukewarm stagnant rainwater for this. A layer of mulch keeps the soil moist and loose while keeping the fruit clean. Always water the root area and not the foliage.

fungal infections

Fungal infections tend to occur on cucumbers in the greenhouse. The most notable of these are cucumber wilt, Verticillium wilt, and powdery mildew and downy mildew. The course of the disease is rapidly progressive in the first two infections. Despite a good supply of water and nutrients, the plants are very limp and wilted. In the case of an infestation with powdery mildew, a whitish coating appears on the leaves before they turn yellow and fall off.

Can the cucumber plant be saved?

Unfortunately, if it is cucumber wilt or Verticullium wilt, you cannot save your cucumber plants. Remove the infested plants immediately and dispose of them in household waste or by burning, never on the compost. This is because the pathogens can survive there and later spread to other plants. Other infections are entirely treatable if caught early. A proven home remedy for fungal diseases is skimmed milk. Mix the milk with water in a ratio of 1:3 and spray it on your cucumber plants daily. Prepare the mixture fresh every day. After about a week you should see success and the fungi should have died. In contrast to the use of chemical agents, the cucumbers treated with skimmed milk can be eaten at any time.

leaf spot disease

Leaf spot disease affects various types of vegetables and can be transmitted to other plants. In the early stages, this bacterial infection only shows yellowish spots on the upper side of the leaves. Only later do the leaves turn yellow, then brown. If the plant is injured, the bacteria get inside, they can also hibernate in the soil. When the humidity is high, the risk of an infestation is particularly high.

cucumber mosaic virus

In the case of an infestation with the cucumber mosaic virus, the older leaves in particular turn yellow, young leaves tend to get yellow spots. The fruits are also affected, they deform and can no longer be sold. However, the virus cannot be transmitted to humans. Dispose of the infested plants and the fruits of the neighboring plants. Before you replant the site with cucumbers, you should change the soil. Transmission of the infection is also possible with garden tools or aphids.

aphids

Aphids are more likely to occur in outdoor cucumbers and only rarely in the greenhouse. The leaves of your cucumbers stun when infested and get a sticky coating called honeydew. The leaves then turn yellow and fall off. Neem oil and spraying the affected plants with a mixture of milk and water are suitable for treatment (ratio 1:2) or the use of beneficial insects, which you can find in any well-stocked garden store receive.

spider mites

Spider mites prefer to appear in greenhouses. The animals are so small that they can hardly be seen with the naked eye. You can recognize the infestation by the fine web that usually sits on the leaf axils and edges or by small light spots on the cucumber leaves. Later, the affected leaves develop brown leaves and increasingly turn yellow. If you don't react quickly enough, your cucumber plant will become bare and die. A chemical treatment is not necessary. Home remedies like neem oil, showering with a hard jet of water, or wrapping individual plants in plastic wrap can also help. The use of beneficial insects is also very effective.

draft

Drafts occur mainly in the greenhouse, where they cause the leaves of your cucumbers to turn yellow. Therefore, ensure constant air circulation without draught. Close the ventilation (windows, door) in the evening and open it in the morning when it is no longer so cold but not yet too warm. Outdoor cucumbers are best planted in a sheltered location.

How can I prevent yellow leaves?

The best prevention is choosing the right location for your cucumber plants and proper care. Cucumbers like it warm, airy and moist. However, you should avoid wet, draughty or windy conditions. The soil should be permeable, not too heavy and at least 10 °C warm. Water the plants regularly but not too much and fertilize as directed. Too much fertilizer can also harm your cucumber plants.

Learn more about plant diseases