Common Cucumber Plant Problems

The cucumber plant is one of the most popular vegetable garden plants. Like peppers and tomatoes, for many they are a staple of the summer vegetable garden. The number of different shapes, sizes and flavors on offer has helped to increase this crop’s popularity. If you need help choosing a cucumber plant variety, this is a guide to 20 of the best cultivars currently available.

Once established and thriving these specimens are prolific croppers, producing lots of healthy cukes. If cucumber plant problems strike even the healthiest specimen can start to struggle and production cease. This has caused them to. somewhat unfairly, develop a reputation for being difficult to grow. But this simply isn’t the case.

Knowing how to treat and identify cucumber plant problems can be difficult and daunting, particularly if you are new to growing your own vegetables. This guide is designed to help you identify the most common cucumber plant problems as well as providing lots of tips on how to treat and prevent any issues that do develop.

1 Cucumber plant disease easy to treat
While many common cucumber plant problems can seem daunting, most are easy to prevent or cure. 

Transplanting can Stunt Growth

One of the most common cucumber plant problems can be traced to transplanting. Easy to grow in position from seed, cuke seedlings can be difficult to transplant. Successfully transplanting can be particularly problematic for gardeners in colder or northern climates who don’t enjoy enough warm weather to grow cukes in position from seed.

Most transplanting related cucumber plant problems usually stem from the fact that these specimens don’t like having their roots disturbed. This can cause them to suffer from transplant shock which causes growth and development to slow. In the worst cases it can even cause specimens to fail completely.

2 Sensitice seedlings
Sensitive specimens require careful handling during transplantation. 

In cooler climates try sowing fast maturing varieties such as Straight 8. Alternatively, start your seeds undercover in biodegradable Seeds Starter Peat Pots. These can be planted with the cukes still in the pots, in the ground, after hardening off. As the cukes develop the pots break down enabling roots to spread.

To help reduce transplant shock, seedlings require a little more post-transplant care than other vegetables. Water the soil around the cucumber plant regularly until they are established and new growth is visible. You can also help your seedlings to settle by applying a diluted liquid organic or homemade fertilizer and covering with a shade cloth for a few days to stop them from getting too hot.

Poor Fruit Production due to a Lack of Pollination

For fruits to be produced each flower must be pollinated. If not properly pollinated the fruit can stay small or become deformed. The more pollinators that visit a flower the better the fruit develops. Or, to put it another way, the more pollinators you can encourage the larger the fruit.

To encourage pollinators, grow pollinator friendly flowers, also known as companion plants, close to your fruit. Good companions include:

Try to avoid using pesticides in your garden. Even some organic products can deter bees.

3 Flowers require pollinating
Flowers require frequent pollination before fruit can begin to form. 

Problems Caused by Lack of Water

A growing cucumber plant is a thirsty specimen. A lack of water can lead to the many common cucumber plant problems, such as growth slowing or foliage wilting, developing. .

Water your specimens regularly and deeply. Ensure that the root zone is thoroughly soaked. Watering heavily twice a week is better than a light watering every day.

Mulching around the stems with straw or shredded leaves helps the soil to retain moisture. This, in turn, reduces how often you need to water your growing cukes.

If your cukes are growing in containers they will require more frequent watering than specimens growing in the ground. This is particularly important during hot, dry spells. During these periods aim to soak the soil around the cukes deeply everyday, until excess water starts to emerge from the drainage holes at the bottom of the pot. If you are growing in pots, this detailed guide is designed to help you get the most out of your cukes.

Problems Caused by a Lack of Nutrition

As well as being big drinkers cukes are also notoriously heavy feeders. Many common cucumber plant problems are caused by underfeeding. Pale or yellow foliage, particularly old foliage is a sign that the cuke needs a dose of fertilizer.

In the spring, if you are growing your cucumber plant in the ground, work compost or organic material in before planting. This provides them with lots of nutrition. In rich soil this should support the cucumber plant throughout the growing season. If foliage does begin to yellow, or the cukes are placed in less than ideal soil, an additional boost may be required.

Apply a liquid, organic fertilizer once a month. Organic granular fertilizers can also be worked into the soil prior to sowing seeds if the soil is deficient. Avoid applying fertilizers that are rich in nitrogen. These cause long, green vines and foliage at the expense of flowers and fruit.

If you are growing in containers, apply a liquid organic fertilizer regularly.

4 Correctly water and fertilize
Correctly watering and fertilizing helps to keep specimens healthy and productive. 

Powdery Mildew

Causing a talcum powder like dust to appear on foliage, powdery mildew is one of the most common cucumber plant problems. While powdery mildew looks unsightly it is easy to prevent. Additionally, many varieties such as Eureka and Transamerica are powdery mildew resistant.

To prevent powdery mildew try to keep the foliage as dry as possible when watering. Like other fungal issues, powdery mildew loves wet foliage. Watering in the morning, so that the foliage has time to dry, also helps to deter fungal problems.

If powdery mildew does develop, organic fungicides based on bicarbonates or products containing Bacillus subtilis can be applied. Before applying any product take the time to read the instructions and use it in as safe a way as possible.

5 Powdery mildew
Foliage affected by powdery mildew can seem like it has been coated with talcum powder. 

Cucumber Beetles

Depending on where you live you may see striped or spotted cucumber beetles. Both love not just the cucumber plant but all members of the cucurbit family. Adult beetles make holes in leaves and flowers. Meanwhile the larvae burrow into the soil to feed on the root system.

Again there are beetle resistant varieties such as Gemini and Saladin. The foliage of these specimens contain low levels of the compounds that beetles like, making them an unattractive proposition.

To deter the pests, cover your specimens with a floating row cover. Agfabric Floating Row Covers not only protect delicate specimens from pests but also from birds, the intense heat of the afternoon sun and keep seedlings warm during unexpected cold spells. Covers should be in place from germination or transplanting to flowering.

Yellow Sticky Traps suspended just above the tops of the cukes can catch the pests as can coating yellow tape in a non-drying glue. However, this preventative measure can also catch harmless or beneficial insects.

6 Cucumber beetles
While these beetles are considered pests, they are also useful pollinators. 

Cucumber beetles are also good pollinators. Many growers choose to leave them in place. Not the most serious of the common cucumber plant problems, these beetles rarely cause serious damage. However, they can transmit the deadly bacterial wilt.

Bacterial Wilt

Bacterial wilt is a pathogen that affects all cucurbit family members including squash and pumpkins. The first sign of bacterial wilt is foliage drying or wilting. To confirm bacterial wilt is present, cut a wilted stem from the base and touch the cut area. If bacterial wilt is present a thin, white thread like strang emerges as you remove your finger.

There is no cure for bacterial wilt. Instead lift and destroy affected specimens to stop the disease from spreading.

Bacterial wilt resistant cultivars include:

  • Salad Bush,
  • Saladin,
  • County Fair.

Fusarium Wilt

Of all the cucumber plant problems discussed here, fusarium wilt is one of the more difficult to identify and treat. Fusarium Wilt is a pathogen that thrives in warm, southern climates. At first causing foliage to drop, as it develops entire branches can wilt. Typically, fusarium wilt typically emerges on the lower leaves first. As it develops the disease works its way up the foliage towards the top of the cucumber plant.

To confirm that this, one of the most common cucumber plant problems, is affecting our cuke, cut open the main stem. If fusarium wilt is present you will see dark streaks running lengthwise through the stem. Dark, sunken cankers can also appear.

Fusarium wilt lives in soil for many years and can affect many different specimens. It can be carried in water or on dirty gardening tools. There is currently no cure for fusarium wilt. Instead lift and destroy affected specimens. Solarize or sterilize the soil and apply a biological soil drench before growing anything in that position again.

Resistant varieties, which have the code FW on the packet, are available.

Cucumber Mosaic Virus

This deadly virus is spread on dirty tools and hands. It is also spread by sap-sucking aphids. Should you notice aphids on the foliage blast the pests away with a hose. Persistent infestations can be treated with neem oil.

Symptoms include a mosaic-like pattern of dark and light green patches to appear on foliage. This can resemble a green chess board. As the disease develops specimens become deformed while the fruit are lined and spotted.

7 Mosaic virus discolors leaves
Mosaic virus can cause foliage to become discolored.

There is no cure for mosaic virus. Instead lift and destroy affected specimens. If mosaic virus is one of the common cucumber plant problems in your area try growing a resistant variety. These have the code CMV on the seed packet. Popular resistant varieties include:

  • Eureka Little Leaf,
  • Straight Eight,
  • Salad Bush.

Alternaria Leaf Blight

This nasty disease is caused by the Alternaria cucumerina fungus. Commonly affecting melons, its spores are spread on the wind and through contaminated soil and water. Alternaria leaf blight thrives in wet, warm conditions. During the winter months the spores hibernate on leaf and stem debris waiting for new spring growth to emerge.

Usually affecting mature leaves this disease causes small brown spots to emerge on foliage. These grow into larger shapes with distinctive yellow halos. The foliage then browns completely before wilting and dying.

Fungicides can be used to prevent or treat infestations. In addition to copper fungicides you can also make your own by combining soapy water, baking soda and vinegar. Should Alternaria Leaf Blight develop, cut away affected parts and destroy. Like other cucumber plant problems, if the infection becomes severe the specimen should be lifted and destroyed.


Anthracnose is caused by the Colletotrichum orbiculare fungus. This is another one of the more common cucumber plant problems. It is particularly common in wet, warm conditions and high humid areas such as the mid Atlantic states. Like other common cucumber plant problems this disease can overwinter on leaf and stem debris.

Anthracnose causes yellow spots to emerge on foliage. Small at first, these grow into large, unsightly yellow marks. It can also cause black, sunken patches to appear on the fruit. Anthracnose is best treated with a fungicide. Cut away and destroy any treated fruit.

Bacterial Leaf Spot

Bacterial leaf spot spreads through lesions caused by insect bites. It can also be spread by water contact. Bacterial leaf spot first presents itself as small brown or black spots to appear on foliage. These spots can sometimes have yellow edges.

Not as resilient as other common cucumber plant problems there is currently no effective treatment. You can prevent the issue by using row covers to prevent pests from accessing your cukes. Growing pest attracting companion flowers such as tansy, catnip and radish nearby also helps to repel common pests such as cucumber beetles.

If infestations do strike, treat promptly with an appropriate organic treatment or insecticide. Using clean tools and spacing specimens out so that air can circulate freely between them also helps to keep foliage healthy.

Rhizoctonia Belly Rot

One of the few cucumber plant problems that affects the fruit, rhizoctonia belly rot is caused by the Rhizoctonia solani fungus.  This disease causes lesions to appear on the fruit. These enable other pathogens the opportunity to enter the cuke.

Like many common cucumber plant problems the spores of rhizoctonia belly rot live in the soil. Thriving in hot, humid weather this disease causes brown water soaked spots to form on the fruit. As these develop and spread they can firm up and crust over.

Currently there is no known treatment for rhizoctonia belly rot. Should the disease strike, cut away affected areas and destroy. Clean your tools and sterilize the soil.

Verticillium Wilt

Like fusarium wilt, this fungi, verticillium dahliae, enters through the root system. Thriving in moist soil and warm temperatures the spores can survive in soil or on garden debris over winter. Verticillium wilt can also be spread by insects, on dirty tools or during watering.

Verticillium wilt causes irregular yellow spots to appear on leaves. As they grow these yellow spots can turn brown. The disease can look similar to leaf blight. However, verticillium wilt spots don’t have the distinctive haloes of leaf bight.

Should your cukes develop verticillium wilt cut away and destroy the affected areas. If the disease continues to spread you may need to lift and destroy the entire specimen. Clean your tools afterwards to prevent the disease from spreading further around the garden and sterilize the soil before growing anything there again. I find that a watering can often gives you more control than a garden hose.

Preventing Cucumber Plant Problems

By caring correctly for your cucumber plant you can prevent many of the problems outlined above. For example, when watering try to water only the soil and keep the foliage as dry as possible. This prevents issues such as mildew from developing.

In addition to this, adopting a crop rotation system or solarizing the soil before planting can help to keep the area disease free. Mulching the soil around the plants can help to keep the soil free from pests. Companion planting also helps to keep your fruit, vegetables and flowers pests free and healthy. If infestations do strike, try to treat them as soon as possible.

Finally, adopting good growing practices such as cleaning your tools and pots, keeping the growing area weeded and free from leaf debris can help to reduce winter hiding places for pests and disease such as alternaria leaf blight.

8 Care correctly for cucumber plants

With a little care you can cultivate your own crop of healthy and productive cukes.

A popular member of the vegetable garden, cucumber plant problems can develop for a range of reasons. However with the right care, the adoption of good growing practices and the selection of varieties that are appropriate for your growing conditions many of these issues are easy to prevent and control. By following the advice laid out in this guide you can enjoy a healthy crop of fresh, homegrown fruit throughout the year.

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