Cucumber Leaves Turning White? (How to Treat and Prevent It)

Growing vegetables in a garden is a simple way to get fresh veggies. Growing certain things is a relatively easy endeavor, too. Even still, there are certain things that can impact things like tomatoes and even cucumber plants.

If you notice that the leaves of your cucumber plants are starting to turn white, there are a few probable causes. It could be due to powdery mildew, another type of disease, or even a pest issue. Resolving and preventing the issue is pretty easy as well.

If you happen to notice that the edges of your cucumber plant leaves are turning white, it is most likely powdery mildew. Powdery mildew is a fungus and typically starts by attacking the leaf edges at the start of its infestation.

If nothing is done to stop its growth, those spores will continue to work their way through the leaf until it is completely white. Even the smallest of spots will grow and eventually merge with one another. If left unchecked, powdery mildew can even cover the stems and stalks as well.

Sunlight prevention. White fungal spores will not necessarily spread to the actual cucumbers. While that may seem like good news, there is a “but” involved. In the more advanced stages, those powdery spores can prevent sun from getting to the foliage. When plants can’t go through photosynthesis, growth can be stunted.

Should the problem go on long enough, your cucumbers will suffer. Stunted growth will mean smaller and fewer cucumbers of a poorer quality.

Have you recently transplanted your cucumber plant from another area of the garden? It is important to know that a lot of plants go through what is known as “transplant shock.” Transplant shock happens immediately in the wake of the cucumber plant being transplanted.

Transplant shock will generally only cause a temporary slowdown in the growth of the plant. If the leaves are turning white in the wake of a transplant, however, there is a bigger problem to be aware of.

Stem or root damage. Should you notice that your cucumber plants are starting to show white splotches or white coloration in the leaves after transplant, it could be a sign of stem or root damage. The most likely cause is the aforementioned powdery mildew, however, so replace the soil.

Fungus will remain in the soil during the winter months before attacking any new plants in the area. So, if you notice that plants grown in the same spot tend to get white spots, fungus is the issue. Dig up and replace the soil in that area to avoid repeating history.

Planting seedlings in your garden is a new beginning. Make sure that you plant your seedlings with as much a success of chance as possible to promote seedling development and germination. You make think that everything went well when the seedlings suddenly look white.

Properly growing and developing cucumber plants should look a healthy green color. When they turn ghostly white, it is a strong indication of fungus growth. The most common problem is a re-use of soil where the fungus has previously grown. Whenever putting a new seedling in, use fresh soil if possible, to avoid spreading fungus from plant to plant.

You may find that tilling and replacing the soil yields no progress. If you can be reasonably certain that there is no fungus at play, the real reason may be due to a pest problem.

Leafhoppers. In particular, leafhoppers tend to be the most annoying for cucumber plants. These wedge-shaped, small insects generally appear to be either green, yellow, or brown in color. They feed by puncturing into the leaf of the cucumber and then sucking out the fluids within.

Continuous feeding on the cucumber leaves can lead to those little white specks that you see near the upper surface of the leaves. When feeding is allowed to persist, the leaves can dry out. In some cases, the ends of the leaves can even look burned.

Get rid of the pests. The good news is that these pests don’t require any type of chemical treatment. The reason being that their feeding activity doesn’t result in any real long-term damage. To keep them from getting to the cucumbers, drape a few floating row covers over top of the plants. When the flowers start to bloom, remove the covers so that any pollinating insects are able to securely reach the blossoms.

Sometimes it may not be a matter of fungal spores or even pests wreaking havoc. Improper spacing and cultural control can be enough to turn those cucumber leaves white, too.

Sunlight. Cucumbers need proper sunlight in order to develop and grow properly. Keeping them in too much shade can rob them of sunlight. They do well in sunlight and those fungal spores will not survive in direct sunlight.

Proper spacing. While it may seem like an arbitrary thing, proper spacing is key to proper cucumber growth. Without proper spacing, the plants don’t have the necessary circulation. And since fungal spores thrive in dark, cool, damp places, that is precisely what they hope for.

Make sure that you plant your seeds at least an inch apart and then thin the seedlings so that they have about 12 inches of space between each of the plants. Proper air circulation helps to keep fungus at bay.

Water stress. Overwatering is another contributing factor to white cucumber leaves. Water stress leaves the plants less able to fight off those fungal pathogens. Make sure that you irrigate slowly on a weekly basis so that the top 6 or 8 inches of the soil gets moist.

Make sure to water your cucumber plants in the morning to give the foliage the time it needs to dry prior to the evening. Remove any debris at the end of the season to prevent pests and fungal spores from overwintering within your garden.