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Why Are My Cucumber Leaves Turning White? (Practical Explanation & Advice)

Cucumber is a fresh, cool, and favorite ingredient in various dishes, especially salad and sandwiches. In addition, it is favorable in terms of overgrowing without much attention.

Despite that, it is undeniable that the cucumber plants might suffer from disease or other external conditions such as pests. Accordingly, growing these veggies on your own or not, you have to acknowledge all these problems to ensure good harvesting

In particular, one of the significant concerns you may ask is: “Why are my cucumber leaves turning white?”. If so, keep reading the article below, which will provide you with insightful points and practical solutions related to this topic. 

Why Are My Cucumber Leaves Turning White
White patches on cucumber leaves…any ideas? via Reddit

Why Are My Cucumber Leaves Turning White?

Powdery mildew is the main reason for making cucumber leaves turn white. In addition, blanch or excess moisture also leads to white spots on them. 

First and foremost, powdery mildew is the common fungal disease stemming from two fungi types: Sphaerotheca fuliginea and Erysiphe cichoracearum

The disease spreads quickly through white growth, starting from small white spots, gradually emerging and covering the entire cucumber leaves. Accordingly, the foliage is prevented from reaching the sunlight for photosynthesis.

In other words, the plants may grow slowly and produce low-quality cukes. The plants further face sunburn once the leaves drop due to fungal diseases in the worst scenario. 

Aside from white spots, other signs help you acknowledge the powdery mildew. For example, it may have some curl and brown leaves at an advanced stage of the fungal disease. Otherwise, the bud drop will give you the sign of that disease. 

Regarding excessive moisture, it often happens when the ground is underwater. This results in quick leaching of nutrients and affects the leaves color. That is why you might see the cucumber leaves white or even in light yellow. 

Lastly, the unintentional blanch is another reason explained for this situation. As a rule, blanching is a way to turn the leaves pale in color via blocking sunlight to prevent photosynthesis.

In this case, you position or plant the veggies in the area, which is hard to expose to sunlight. As a result, the cucumber leaves turn pale and white due to stop chlorophyll production

Why Are My Cucumber Leaves Turning White 2
“Why are my cucumber leaves starting to turn white?” via Reddit

3 Tips To Treat When Cucumber Leaves Turn White 

Once the advent of white spots, it is vital to prevent these symptoms immediately. Otherwise, the cucumber leaves might seriously affect the general growth. Accordingly, don’t skip this part to explore valuable and practical solutions. 

Powdery mildew treatment 

  • Indeed, the earlier you treat the fungal disease, the finer the cucumbers will be.
    • Otherwise, the white growth quickly spreads and affects the whole crop. In this case, use some substances following to spray to prevent the disease.
    • Importantly, please remember that it is not recommended to spay when the temperatures are highly over 90 degrees F or veggies with drought stress.
    • Otherwise, you may not present the powdery mildew and produce side effects on the plants. 
  • Neem oil: it is a common and effective natural fungicide to treat white cucumber leaves once you acknowledge the sign of some minor white spots.
    • In addition, you probably mix the neem oil with other liquid or substances, such as water, milk, or vinegar, for better performance in affected areas. 
  • Baking soda: another trusted spay option is baking soda—mix baking soda with planted dish soap and water with a 1:1:1 ratio.
    • Then spray entire veggies with that mixture.
    • Baking soda comes in handy when you desire to treat the intense effect of fungal diseases. 
  • Milk: You might take advantage of skim or organic milk as an alternative to kill the powdery mildew.
    • Indeed, the milk has numerous attributes to antibacterials but also immunity boosting.
    • Accordingly, mix milk and water in a 1:9 ratio and spray that mixture on both soil and plants, especially under the leaves, for an effective result. 
  • Vinegar: Another natural option to treat powdery mildew is vinegar.
    • Indeed, the acetic acid in vinegar plays a vital role in this fight.
    • However, don’t abuse the substances too much to spay since they might cause fruit burning.
    • Regarding the mixture to spray, combine water (1 gallon) with vinegar (3 tablespoons) and spay gently on the cucumber plants.
  • Commercial product: Generally, it is essential to use commercial fungicide once the infection is no longer light and becomes more intensive.
    • Indeed, you might get the product quickly at some grocery store.
    • Despite that, make sure you pick the natural and non-toxic fungicide and keep an eye on its usage to apply correctly.

Excess moisture treatment 

The root cause of excessive moisture problems is the flooded ground. Accordingly, it is vital to water plants only when dry. 

Despite that, watering is unnecessary if you find high humidity. In this case, you might take advantage of rich fertilizer to provide essential nutrients and water for the plant’s growth. Accordingly, you probably avoid overwatering and prevent the white spots issues on cucumber leaves. 

Blanch treatment 

Regarding the blanch problems, it is simpler to solve than you think. First, try your best to manage and control the plant space that your veggies are exposed to enough essential sunlight. 

Importantly, keep an eye to track whether the light reaches every leaf or not. In addition, you may trim the unwanted leaves from other neighboring plants to provide more space for the plants to access the sunlight.


Briefly, numerous things lead to white spots on cucumber leaves, powdery mildew, excessive moisture, and blanch are the common reasons in this case. Indeed, the high-frequency rate of white growth mainly stems from powdery mildew. 

Acknowledge the cause and sign when the cucumber turns white to support you in preventing the spread of effect over the entire crop. Hopefully, the detailed explanations and valuable treatments mentioned above will ease your mind in the process of dealing with this situation. 

Should you have any questions, feel free to drop a comment below. In addition, if you find the article helpful, don’t hesitate to share it with your friends and relatives.