Food Gardening Network

Growing Good Food at Home

How to Spot, Treat, and Prevent Cucumber Diseases

An afflicted cucumber plant.

An afflicted cucumber plant.

Cucumber plant diseases are caused by bacteria, fungi, and viruses. The diseases can spread through the soil, water, air, infected tools, animals, and even gardeners themselves.

Spot diseases on your cucumber plants sooner so you can treat plants before they are destroyed by disease and can successfully manage symptoms. Here is a three-step approach to keeping vigilant about the presence of cucumber plant diseases:

  • Research the Risks. Find out about cucumber diseases that are prevalent in your geographic area. When possible, buy disease-resistant cucumber plant varieties to avoid diseases in the first place—many hybrid cucumber varieties have been specifically designed to resist certain diseases.
  • Examine Plants Daily. Check your cucumber plants every day to be sure no disease symptoms are present or emerging.
  • Spot Diseases Early. Catch and treat disease quickly so your plants can recover and thrive.

Cucumber diseases can affect the leaves, stems, and fruit. Here is what to look for to spot possible infection:

Cucumber leaves—possible disease symptoms:

  • brown, yellow, or black spots
  • powdery whitish spots or layers
  • sudden wilting, turning brown or yellow (despite adequate watering)

 Cucumber stems—possible disease symptoms:

  • presence of milky sap, when cut
  • mildew
  • brown or yellowing
  • stunted growth

Cucumber fruit—possible disease symptoms:

  • brown spots or lesions
  • misshapen or undeveloped fruit
  • yellowing fruit

Make your own natural disease and pest control spray with benign materials. Mix one tablespoon of baking soda, 1/2 teaspoon of a mild dish detergent, and 2 1/2 tablespoons of olive oil in a gallon of water to make a solution that will repel all kinds of bugs, as well as a fungicide for blight and mildew on the cucumber plant leaves. Shake it well in your bottle before spraying, and repeat every week for it to be continuously effective.

We’re believers in not using toxic materials in the garden—they can hurt the plants, hurt the soil, damage the environment, and harm you.

Preventive measures to avoid cucumber plant diseases

Planting healthy cucumber seedling.

Planting healthy cucumber seedling.

You’ll save yourself a lot of time, trouble, and ruined crops if you take some preventative measures for avoiding cucumber diseases.

Rotate crops regularly

Many bacteria, fungi, and viruses live in the soil for years and are just waiting to prey on your cucumber plants! Minimize the likelihood of these diseases when you plant cucumbers by planting no more than once every three years in the same location.

Avoid planting other crops such as melons, zucchini, and water-loving plants like potatoes near your cucumbers. Plants from the same family are often susceptible to the same diseases, and other water-hogging plants can weaken your cucumber plants, leaving them more vulnerable to disease.

Improve your soil composition

Before planting your cucumbers, add a good amount of compost or organic matter to improve the soil. Extra nutrients and good aeration help grow stronger plants that will resist disease and infection.

Plant disease-resistant cucumber varieties

Many hybrid cucumbers varieties have been developed specifically to resist particular cucumber diseases. You can plant disease-resistant cucumber varieties to always have the healthiest plants and harvest. Cucumber disease resistant codes are listed on seed packets or seedling containers in capital letters. They include:

  • A = Alternaria
  • ALS = Angular Leaf Spot
  • B = Bacterial Wilt
  • BLS = Bacterial Leaf Spot
  • CMV = Cucumber Mosaic Virus
  • CVYV = Cucumber Vein Yellowing Virus
  • DM = Downy Mildew | Water Mold
  • F = Fusarium Wilt
  • PM = Powdery Mildew | Fungus
  • S = Scab | Fungus
  • TSP = Target Spot | Fungus
  • V = Verticillium Wilt

Water your garden properly

Don’t underwater or overwater your cucumber plants. By keeping a regular watering schedule, you’ll keep your plants vibrant and healthy. Overwatering and watering directly on the plants—instead of the preferred watering method, directly at the stem on the soil—leads to consistently wet conditions, which allows bacteria, fungi, and viruses to thrive and multiply.

Clean and disinfect your tools

You can inadvertently transfer diseases from the soil and other plants to your cucumber crop through your tools and gardening gear. Regularly sanitize your boots, gloves, spades, shears, and any other objects that come in contact with the soil and other plants. If you’re using containers, clean them out with bleach after the growing season ends to kill diseases.

Destroy infected plants

Throw away or burn infected plants. Don’t keep infected plants over the winter in your garden, and don’t throw them on your compost pile. Disease-ridden plants, even when dead, will spread the disease to other plants or even your soil.

Have you had problems with diseases attacking your cucumber plants? What types of problems do you regularly face with your cucumbers? Please tell us how you treat and prevent diseases from destroying your cucumber crop.


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