5 Common Cucumber Diseases - Backyard Boss
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5 Common Cucumber Diseases

Cucumbers are a favorite among many home gardeners because they are easy to grow and harvest. Plus, cucumbers tend to grow and grow, boasting a bountiful harvest that gardeners can enjoy all season long. They also come in different varieties that you can use for anything from pickling to salad toppings to relish.

With all that in mind, there are several things that can go wrong, including one of these common cucumber diseases. Below, you’ll discover the signs of the most common diseases and how to treat them, as well as several preventative measures to ensure you enjoy a harvest filled with crisp and refreshing cukes.

Cucumber Mosaic Virus

Mosaic virus on the leaves of a cucumber plant in a UK garden
Image credits: Paul Maguire via Shutterstock

Cucumber mosaic virus affects a wide number of plants and can have a significant impact on vegetable production, yield, and quality. General symptoms include stunted plant growth, growth distortions, warts on fruits, and spotty white, yellow, and light green areas on the leaves.

Seeds and pollen from host plants can carry the virus, but more commonly, aphids transmit it around the garden. Immediately remove infected plants from the garden to halt the spread. You can burn or compost the plants, making sure to keep them away from the garden.


Anthracnose of cucumbers.Colletotrichum orbiculare.Cucumber leaf with dry brown and yellow spot.Disease treatment concept.
Image credits: Helen Liam via Shutterstock

Anthracnose is common among cucurbit plants during warm, rainy weather. It covers all areas of the plant, from seedlings to mature leaves, in unattractive lesions. The fruit can develop a bitter taste and become susceptible to rot. The lesions become dry, dead, and sunken, and may even kill off young fruits. It is also common in tomatoes and known as fruit rot.

The disease can spread through infected debris, weeds, and by cucumber beetles. Warm weather, humidity, and rain provide conditions in which anthracnose thrives. All infected vines should be immediately removed and destroyed to avoid spreading the disease. Also, avoid working on the plants when wet and do not soak the leaves when watering. Proper crop rotation can help with anthracnose as well. 

Bacterial Wilt

A young zucchini bush after night frosts. Drooping green leaves after a negative temperature. Recurring spring frosts. Cultivation of squash affected by leaf diseases and pests in the garden.
Image credits: yizhachok via Shutterstock

Bacterial wilt causes cucumbers to die rapidly and you should treat it immediately. Fortunately, it’s quite noticeable and you should spot it quickly. At first, you may notice that the leaves are dull green. They will also wilt during the day and recover at night, eventually becoming yellow, wilting completely, and dying

Striped and spotted cucumber beetles carry bacterial wilt and spread it throughout the garden. To treat the disease you will need to remove all infected plants and follow treatment protocol for cucumber beetles.

Powdery Mildew

Close up of cucumber leafs with white powdery mildew. Plant disease
Image credits: matahiasek via Shutterstock

As the name would suggest, powdery mildew causes a noticeable white powdery growth on the surfaces of leaves and stems. It can often result in stunted growth and cause fruits to prematurely drop. The fruits should still taste and look the same – just appear a bit smaller.

Powdery mildew often occurs in dry, warm weather with poor air circulation. Remove infected plants immediately after harvest to avoid spreading the disease, though preventative fungicide treatments are available. To prevent the issue, properly prune the plant to provide plenty of air circulation.

Gummy Stem Blight

Gummy Stem Blight cucumber causal agent Didymella bryoniae
Image credits: AmBNPHOTO via Shutterstock

Gummy stem blight, also known as black rot, affects many cucurbit plants at any stage, causing light-to-dark-brown spots all over the plant (except for the roots). The lesions will cause cracking and a notable gummy ooze. The disease can also cause vine wilting later into the infection.

The fungal disease spreads through seeds, weeds, and debris, and can rapidly spread from there. Leaf wetness, high temperatures, and high humidity provide the perfect environment, so it’s important to watch your plants during warm weather and be careful of your watering techniques.

Preventing Cucumber Plant Diseases

Healthy cucumber plant
Image credits: artellliii72 via Pixabay

Preventing cucumber plant diseases requires a few very simple steps that are in line with general plant maintenance and care. Check out some of the best ways to prevent diseases from starting and spreading below.

  • Choose disease-resistant varieties
  • Clean tools, pots, and gloves after each use.
  • Grow companion plants.
  • Keep an eye out for pests.
  • Provide proper care, drainage, and sun.

Cool as a Cucumber!

Though many diseases could be impacting your cucumber plants. They are generally easy to spot and treatment is sometimes an option. Regardless, prevention is always the best method to ensure your plants stay happy and healthy and you won’t have to worry about handling any diseases!

If your plants aren’t doing so well but you haven’t noticed any signs of disease, be sure they’re not suffering from any pests. Otherwise, you may be making some common mistakes without realizing it!

How do you care for your cucumber plants? Share in the comments below!