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Cucumbers leaves turn yellow: what are the causes and the appropriate treatments of the plants?

Cucumbers are refreshing summer treats that provide an abundance of vitamins, minerals and moisture. As one of the most commonly grown garden vegetables, the plants can grow and produce mightily under the right conditions. However, when the leaves start to turn yellow, it may be time to review your growing situation. Cucumber leaves turning yellow? You shouldn’t fret, as there are several reasons for this and solutions to this common garden problem.

Why do your cucumber leaves turn yellow

Cucumber leaves turn yellow because of diseases and pests

Yellowing of cucumber plants is no small matter. In some cases, the plant may die before it bears fruit. Below are some reasons why the leaves may show yellow spots:

Maintain light conditions

Insufficient light can be the main reason for yellow cucumber leaves

Light can be the main reason for yellow cucumber leaves. Whether you grow them indoors or outdoors, make sure they get enough sunlight. Plants need six to eight hours of sunlight daily. So, put the plants in a location where they get six hours of light. If you are growing the plants indoors, use additional LED or fluorescent lights.

Water level is critical

Your cucumber plants need to get the right amount of water

Your cucumber plants need to get the right amount of water. Overwatering will cause a lack of oxygen to the roots. This will also cause the cucumber leaves to turn yellow and begin to wilt. Insufficient water supply can also be responsible for yellowing of the leaves. Remember that the plant needs one to two inches of water every week. If the soil has drainage problems, try loosening it by mixing in sand.

Cucumber leaves turn yellow because of pests

Pests are also one of the reasons for the discoloration of the leaves


Pests are also one of the reasons for discoloration of leaves. The most common pests that affect cucumbers include potato cicadas, spiders, aphids, mites and whiteflies. Here you can get more detailed information about these pests and how to get rid of them to save the plants.

Diseases that damage the plants

Cucumber plants need six to eight hours of sunlight daily

Bacterial and fungal diseases are often responsible for yellow spots on leaves. They can also cause the plants to die. Common cucumber diseases include the following.

a) Mosaic virus

Mosaic virus affects more than 150 plant varieties, including cucumbers. It lives in the soil and therefore can infect other plants throughout the year. The virus causes the plants’ leaves to fold or bend downward and show yellow or brown spots. If you leave your infected plants unattended in the garden, the virus will be spread by grasshoppers and aphids. What to do. There is no way to treat plants infected with the virus. Eliminate infected yellow cucumber leaves or plants as soon as possible to prevent spread. Destroy diseased plants as soon as you discover the virus.

Cucumber leaves turn yellow - learn about the causes and the appropriate measures to take


b) Downy mildew

Downy mildew is one of the most destructive leaf diseases . It is caused by Pseudoperonospora Cubensis. Telltale signs include yellow spots on the leaves and gray mold underneath. Later, these spots turn brown. Remember that damp and cool conditions favor the development of this disease. What to do. Improve air circulation around your plants using trellises. Keep your garden free of debris to help solve the yellow leaf problem. Try drip irrigation or wide row spacing to keep leaves dry. Eliminate infected plants.

Downy mildew is one of the most destructive leaf diseases of cucumbers

(c) Fusarium wilt.

Fusarium wilt is a soilborne disease caused by the fungus Fusarium oxysporum f. sp. cucumerinum. This fungus can thrive in the soil for long periods of time. It causes leaves to turn yellow at the edges and then inward. The virus develops on older plants and leaves. What to do. Remove the infected plants and debris immediately. Protect your plants with light row covers to prevent future outbreaks.

Bacterial and fungal diseases are often responsible for yellow spots on leaves

(d) Anthracnose leaf spot disease.

The fungus Colletotrichum orbiculare causes anthracnose. Anthracnose infection begins with irregular, water-soaked leaf spots. These spots turn yellow and then change to a brown color. This disease develops under humid and warm environmental conditions. What to do. Remove infested seeds and plant debris immediately. Leave plenty of space between plants. Cut off weeds and excess leaves regularly.

Cucumber leaves turn yellow due to nutrient deficiency.

Supplement your soil with fertilizer regularly to promote good cucumber development

Cucumbers need lots of nutrients to thrive and grow. If they don’t get enough of these nutrients, chlorosis will occur. To determine if your plant is suffering from nutrient deficiencies, have your garden soil tested. Below are the most common deficiencies that can cause yellow cucumber leaves.

a) Nitrogen.

Nitrogen is an important nutrient for plant growth. Leaves turn yellow at the tips and along the central veins when nitrogen levels drop. Nitrogen deficiency also inhibits plant growth. What to do. Purchase a high-quality soil fertilizer that has the proper dilution rate. Add a two-inch layer of compost to increase nitrogen levels. Add a tablespoon of ammonium nitrate when you see the plants blooming. You can reincorporate it into the soil three weeks later.

Insufficient water supply can be responsible for yellowing leaves

b) Phosphorus

Do you see bronze or deep yellow cucumber leaves? If so, this indicates a phosphorus deficiency. Phosphorus is essential for normal development of reproductive organs and roots. A deficiency of phosphorus can stop fruiting and stunt growth. Plants deficient in phosphorus are crippled and have weak roots. What to do. Supplement your soil with fertilizer on a regular basis. Perform a soil test to determine the phosphorus status of the soil.

If the plants do not get enough nutrients, chlorosis occurs

c) Potassium

Potassium deficiency first appears on the older leaves. It causes the leaves to turn yellow at the edges and tips. It then spreads between the main veins toward the center of the leaf. Young leaves tend to look dull and small. The fruit appears narrow at the end of the stem. This gives the fruit a club-shaped appearance. What to do. You can provide your plants with a balanced fertilizer to eliminate the problem . Treat the soil for alkalinity or acidity. Bury citrus peels around the affected plants.

Proper care can prevent yellow leaves on cucumbers

d) Zinc

Zinc deficiency leads to the fact that the leaves of cucumbers become yellow and flabby. The leaves also become very small. It also inhibits the growth of the cucumber. What to do? The easiest way to solve this problem is spraying with zinc sulfate solution or organic seaweed.

e) Iron

Iron deficiency causes interveinal chlorosis in young leaves. This is a yellowing with green veins, but the older leaves remain green. What to do. There are two ways to fix this: either treat the soil or treat the plants. You can spray liquid iron on the foliage of the plant. To treat the soil, use chelated iron in powder or granular form. Note: You can also test the pH of the soil and improve it to bring it below 7.

Cucumber leaves turn yellow due to lack of nutrients

f) Calcium

When plants grow in wet conditions, they can also become calcium deficient. Growing leaves look distorted and may bend downward. What to do. Limit the use of ammonium-based fertilizers. Apply lime to acidic soils.

g) Magnesium

Magnesium deficiency causes yellowing and veining on older leaves. Severe deficiency results in light browning in the yellow areas. In addition, the fruit yield is reduced. What to do. Spray soluble magnesium nitrate. You can also spray Epsom salt solution to treat your yellow cucumber leaves.