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Why are Cucumber Leaves Turning White

When you are into vegetable gardening, you can spend ages tending to your crops and vegetables.

All can be going well until you begin to spot white patches on the green leaves of your cucumber plant.

If you are new to this, you may wonder what is making the leaves of your cucumber turning yellow in color, or some cases, they appear to have what looks like white powdery spots.

Cucumbers piled up together

In our quick guide, you can learn what is causing this fungus, and most importantly, how you can treat it and stop it on infected plants. (Read Why are Cucumbers Bitter)

What’s Wrong With My Cucumber Leaves?

You will need to determine the issues with your cucumber plants to understand what the problems are.

Do your plant leaves wilt, even with watering? Can you see brown, white, or yellow spots on your cucumber leaves or the cucumber fruits?

It is likely; your cucumber plants are infected with the disease, which is bacterial, viral, or other fungal pathogens. If left untreated, you could find your plants not producing any fruit, and even if they do, the fruit may not be edible. (Read White Spots On Squash Leaves)

Here’s a handful of diseases you can find on your cucumber plants, although depending on the color of the spots, there are some reasons more than others for what they could be.

  • Alternaria Leaf Blight
  • Anthracnose
  • Bacterial Leaf Spots
  • Bacterial Wilt
  • Cucumber Mosaic
  • Downy Mildew
  • Fusarium Wilt
  • Powdery Mildew (Podosphaera xanthii or Erysiphe cichoracearum)
  • Rhizoctonia Belly Rot
  • Verticillium Wilt

Why Are the Leaves on My Plant Turning White?

If plant leaves turn white and die then the causes are often sun scorch or powdery mildew.

Both cause white spots on cucumber leaves, although they are different. The spots will look different and also will the treatment.

Sun Scorch

Sunscald is most likely to occur on your cucumbers during the spring, summer and into early fall. It has the appearance of bleached-out patches dotted around your cucumber leaves. Small cases of scorching won’t affect your cucumbers, yet prolonged exposure can cause leaf drop and other issues.

Powdery Mildew

Powdery mildew is very common and affects many plants besides cucumbers. The white coating spreads quickly causing leaves to wither and fall off. It may have the appearance of talcum powder, but is a fungal disease or type of mold.

Powdery mildew likes warm weather with humid environments. If you are growing in a greenhouse, this is ripe for infection.

If untreated, the infection of downy mildew will turn leaves white, yellow, and then they die. Watering from overhead late in the day is often a cause, so early mornings and water the soil of your garden.

How Do You Get Rid of White Spots On Cucumber Leaves?

You can use various methods in the treatment of your cucumber plants such as fungicides and pruning the infected plant parts. These can stop the spread, yet you can do more with the application of pesticides and some very effective home remedies.

You do need to make sure you follow some preventative measures as well as because these can stop the risk by a considerable amount. The steps below can help prevent the spread and help with treatment.

  • Clean all tools, boots, and gloves after you have used them around infected plants
  • Sanitize pots with weak bleach before you use them
  • Never leave plant debris lying around your plants
  • Irrigate under the soil – avoid overhead watering
  • Create barriers between cucumbers and soil with plastic mulch
  • Use crop rotation planting practices each year
  • Grow companion plants
  • Control pests such as aphids and the striped cucumber beetle
  • Plant thinly so there is lots of air circulation between plants
  • Plant mildew-resistant varieties if you have an infection

Sliced cucumber in white background

While these are to geared toward this fungal disease and getting rid of the white powdery mildew, you should make sure to use these practices to stop fungal spores on any of your other vegetables.

How Do You Get Rid of Powdery Mildew on Cucumbers?

If you are going the organic gardening route, then you don’t have to panic as there are some very effective ways to deal with your fungus problem.

You will see the fungus as white spots on the leaves, and then the spores spread as powdery patches and thin mold. Nutrients are sucked from your plants, and it will spread through everything if you don’t treat it. (Read what is the difference between vegetables and fruits)

Here are the best organic methods of dealing with mold on cucumber leaves.

Neem Oil: remove the worst affected leaves. Bag them, so the spores don’t spread. Water your cucumbers in the ground, and then apply neem oil to your plants. Make sure not to add it under full sun.

Milk: Milk makes a quick deterrent you can use. Dilute one-part milk to 10 parts of water, and then spray on your cucumbers in the early part of the days. Don’t estimate the dose of milk as too much, and you can attract other pests. Apply this weekly or bi-weekly.

Baking Soda: Baking soda happens to be the most effective treatment for powdery mildew as well as the hundreds of other uses you find around your home.

Add 1 tablespoon of baking soda, to one gallon of water.

You do need to add something to help the solution stick to the leaves. Some gardeners use dish soap, or you can add a bit of cooking oil or even your Neem oil.

The way this works is that powdery mildew needs a neutral pH to flourish, and once you add the baking soda, this changes the level by enough to make the environment inhabitable for the fungus. (Learn How to Grow a Lemon Tree From Seed)

Spray this on your dry plants one per week or every few days and alternate with a spray of milk and water on alternating weeks. There shouldn’t be any reason to spray the fruit as the downy mildew only attacks leaves and flowers.

All the above can help when you spray the treatments with a few days in between. While the spores like warm weather, watering or treating in the morning can go a long way to stop this forming.

Read more: How To Treat Blackspot On Roses

Why are Cucumber Leaves Turning White