How to Combat Cucumber Diseases

Last update: May 4, 2021

Cucumbers are susceptible to different diseases: mostly fungal and viral infections. A few of the most common cucumber diseases include powdery mildew, bacterial wilt, cucumber beetles, cucumber mosaic, and downy mildew.

Fortunately, lots of these diseases can be treated. Take a peek at the article below to learn how to keep your cucumbers happy, healthy and tasty.

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What Are Some Common Cucumber Diseases?

1. Powdery Mildew

It is one of the most common diseases in cucumbers. Powdery mildew shows signs of white powdery substance encompassing the whole leaves of the plant. Usually, it begins in little spots then scatters throughout the leaves.

This fungal disease may cause poor growth of the fruits specifically if the infection is severe. The leaves of the cucumber begin to wither and then fall off prematurely. Overhead watering and poor air circulation can contribute to such problem.

At the first sign of the disease, the use of fungicidal sprays can help. In order to avoid wetting leaves, use underground or surface watering method.

To keep the infection at bay, plant cucumbers in full sun. If your plants are already infected with powdery mildew, spraying with neem oil can prevent the disease from spreading. Just remember not to spray in the heat of the day.

Here’s a great video explaining how to treat powdery mildew.​

2. Bacterial Wilt

Bacterial wilt can cause the plants to wilt and then die fast. You will know if the disease is present in the plant when a white substance will stick to your finger the moment you pull it away.

The bacteria that are causing the disease invade the plant’s vascular tissues, which leads to a rapid wilt of the plant. The sticky substance produced by the bacterial wilt organism plugs the tissues, preventing the transport of water.

As the disease progresses, it begins with a single leaf then the entire plant. In order to control the infection, destroy any affected plants. It is also best to implement the right insecticide program to control bacterial wilt and prevent it from occurring.

Here’s an awesome video explaining how to spot bacterial wilt.​

3. Cucumber Beetles

Cucumber beetles are known for their black and yellow stripes, while some of them are spotted. These insects chew small holes in the fruit’s flowers or leaves.

They usually carry wilt disease and love to suck on young seedlings. Aside from this, the larvae of these pesky insects feed on the roots. One thing you can do with cucumber beetles is pick them by hand. They move slow during the morning or evening.

To kill them, prepare a cup of soapy water and drop them. On the other hand, keep the bugs at bay by applying pesticides. Once the seedlings blossom, stop spraying for cucumber beetles to allow bees to start pollinating the plants.

Here’s what a striped cucumber beetle looks like:​

Cucumber beetle damage

4. Cucumber Mosaic

This type of cucumber disease affects the flower, leaf, stem and growth of the plant. When the infection strikes, it may lead to the formation of prominent foliar yellow mosaic, severe plant stunting, malformation, reduction of leaf size, downward leaf curling and more.

The flowers may show signs of prominent abnormalities. This disease is very common. The virus is transmitted from one plant to another by various kinds of aphids.

Good thing, mosaic disease can be managed by controlling the presence of cucumber beetles and aphids throughout the season. It is best to use good quality seed all the time. Control perennial weeds to prevent the disease from occurring. On the other hand, you may also use insecticides and mineral oils.

Here’s a great paper on Cucumber Mosaic Virus from the University of Hawaii at Manoa.​

cucumber mosaic

5. Downy Mildew

A cucumber plant has downy mildew when it shows signs of angular yellow spots on its leaves. This fungal disease can be treated and prevented in different ways.

If your plant is already infected with the disease, pull it to prevent the infection from spreading. Use good cultural practices to avoid the infection from occurring and use fungicides to stop the disease.

Check out this video from the Rustic Garden to learn more about spotting and treating downy mildew.​

Are Deformed Or Misshapen Cucumbers Infected With A Disease?

Some people think that misshapen or deformed cucumbers are diseased. However, when a cucumber is funny shaped, it does not mean it is infected with a disease. There are possible reasons deformed cucumbers occur.

One possible reason is poor pollination. If there is low insect activity in your garden, it may lead to misshapen cucumbers.

Plants need honeybees for pollination and this process should not be interrupted. Other reasons for funny shaped fruits are high temperature, insufficient water and too much fertilizer.

Here’s an awesome video from Man Living Naturally if you’re really having trouble with deformed cucumbers:​

Why Do Cucumbers Turn White?

Nowadays, there are cucumber seeds that are bred to produce white fruit. However, if you have planted green cucumber varieties but you get white cucumbers, one possible reason is powdery mildew.

When it spreads, the whole fruit may be covered with the mold. However, when a cucumber appears white it does not necessarily mean it is infected with a disease.

There are another two possible reasons cucumbers turn white. The first one is blanching, which occurs when the fruit is entirely covered by leaves.

Keep in mind that cucumbers are in need of sunlight to develop and be able to maintain its green color. To prevent blanching, make sure to position the fruit appropriately so that it receives the right amount of sunlight it needs.

It is advisable to snip out a large leaf or two to expose the fruit. On the other hand, excessive moisture may also cause cucumbers to turn pale or white. Water tends to leach nutrients from the soil.

The absence or lack of nutrients changes the color of the fruit into white. To address the problem, water only when necessary and use a fertilizer rich in phosphorus. It is best to keep in mind that diseased white cucumbers are not safe to eat. However, those cucumbers that turned pale or white due to blanching or too much moisture can be eaten.

There are different varieties of cucumber. Most cucumbers diseases are fungal infections. The good news is, you can avoid these problems by selecting and planting cucumber varieties that are disease-resistant. On the other hand, you need to act fast and find a solution at the first sign of infection. When using insecticide, always wear protective clothing and gloves.

Photo Credits

Photo by Scott Nelson licensed under CC BY 2.0.

Photo by Rob Mitchell licensed under GNU 1.3..

Photo by Scot Nelson licensed under CC BY 2.0.

Pruning Cucumbers: When and How

Last update: May 4, 2021

Pruning is the process of removing laterally growing shoots from the main vine of the cucumber. It can keep your plants healthy and looking good, and it can help avoid overgrowth as well as facilitate vertical growth if you’re using a trellis. You need a few good tools to do the job (we list these below), but once you have those, pruning is really pretty easy. Let’s dive in.

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Quick video if you’re in a hurry…

Here’s a great video from Get Up & Grow for those of you who prefer a more visual tutorial.

Pruning Prep

You should start tending your cucumbers early enough after transplanting the seedlings to make sure that only healthy cucumber plants reach to the bearing level.

Cucumbers have very tender vines, and they should be handled with care to avoid breaking them. It should be noted that pruning should be done routinely to achieve best results. With pruning, you will have disease free plants that will attain maturity early enough and have a long production life.

Pruning aims at reducing the number of laterally spreading shoots, damaged vines, and achieving well-aerated cucumber plants. It also leads to high and quality cucumber fruits.

Why should you prune cucumbers?

Pruning is a technique that improves not only production but also enables your cucumber plants to give better quality fruits. It is a routine management practice that helps you keep check of wild growth.

The cucumber vines produce multiple shoots from a single stem. By pruning, it enables maintaining healthy plants. Also, trimming damaged or excess shoots helps provide sufficient nutrition which in turn allows vigorous fruit production.

Trimming minimizes shading and allows maximum sunlight penetration which increases photosynthesis thereby improving production. Moreover, it eliminates the likelihood of having some pests harbored within the poorly aerated bushes which might exacerbate disease occurrence.

Cucumbers are highly susceptible to diseases, a concern which calls for proper monitoring of the plants. You can easily track the progress of your fruits by keeping fresh foliage out of way further helping you control diseases. You should, however, avoid extensive pruning which would potentially reduce yields. Lastly, moderate pruning enables easy picking of fruits.

Plus, as Jason Ellis points out, pruning can increase your crop yield:​

When is the best time to prune cucumbers?

Once the cucumber plant has grown a few feet above the ground, and it starts flowering, it’s about the right time you start pruning.

It might sound a little bit off, but it is advisable to start pruning early and removing the first flowers with the vision of better yields in the long-term. All you should be keen at is letting the vine produce seven leaves then you can start production.

Pruning should be done early so that the cucumbers will be able to support fruits later on. It is also prudent to keenly check on new shoots and get each of them off early enough. Pinching all the fuzzy growing tips will allow for the lateral spreading of plants.

For cucumbers that grow within cages, those tips growing beyond 4-feet should also be cut off. Well pruned cucumber plants are healthy, and they develop proper root systems which can sustain the weight of fruits.


What tools do you need to prune cucumbers?

There are some tools that you can use for pruning though you are not entirely limited to the ones available. You can also use your hands. You can pinch young shots quickly with your hands which further simplifies pruning since they are fresh and soft. They are also effective since you can take care of the main vine to avoid stretching it which can be damaging. Tools that you can apply in this process include:

  • Pruning shears. They can be to nib shoots especially the ones on the main vine and those of sub vines protruding from the main vine.
  • Secateurs. Secateurs can be used to prune damaged vines. There is a broad range of secateurs to choose from. They come with different blades, sizes, and orientation to suit either left or right-handed gardeners.
  • Loppers. They are used where secateurs cannot be applied where there are thick stems. Mini and lightweight models are used in cucumber pruning.
  • Garden scissors. They are primarily used to cut flowers that come from an early age and thin vines and shoots efficiently.
  • Long reach pruners. They are used to cut off shoots or vines that are difficult to access especially for cucumber plants growing over cages. They have long arms that suit their application.

How do you properly prune a cucumber?

  • First, locate the main vine of the cucumber. The main vine is the one that has not branched out. You should go to the base of the plant and follow it up.
  1. Spot all laterally growing shoots and remove them. These shoots if left, form runners which significantly reduce production.
  • You should eliminate 4-6 shoots growing from the base of the main vine up. All other shoots growing beyond should be left to grow.
  • You should then repeat the process for all plants while tying the vines to the support structures or trellis. It is important to avoid bending vines too much or tightening the vines to avoid breaking or crushing blossoms which may make the vines wilt and eventually die.
  • Remove all damaged and unhealthy cucumbers</strong > that would be appearing undersized as they would be diseased. Mature fruits should be harvested timely to avoid poor quality cucumbers of big sizes.

If you follow through every of the practices as mentioned above and implement them in your farm while combining them with other practices, such as proper application of fertilizers and use of pesticides, weeding, and others, you’ll be sure to reap rewards.

Using pruning to grow vertically.

Here’s an awesome tutorial from GrowingYourGreens that shows you how to use pruning to help your cucumbers grow on a trellis.

Is pruning ever a bad idea?

It is not advisable to start pruning cucumbers when they are too young. It might weaken vines while some may end up getting damaged. Also, it is not wise to prune immediately after spraying pesticides to avoid wastage.

After harvesting starts and there are many mature fruits, the level of pruning should go down. Similarly, pruning while is rainy, and there is high humidity is discouraged because it might encourage the spread of diseases between neighboring plants when vines come into contact.

Since lateral shoots grow very fast, you should cut of all new shoots for proper root development especially as vines get to the rapid development stage when the shoots are sprouting sporadically.

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