Why Are My Cucumber Plants Wilting And Dying?

Wilting is a common response when your cucumber plant is suffering from environmental, bacterial, or fungal stress.

Quick identification of the problem and appropriate action is essential if you want to stop your cucumber plant wilting and dying.

In this article, we’ll take a look at the most common causes, and what you can do about it.

Let’s dive in.

Bacterial Wilt

Cucumber beetle

Cucumber beetle

Bacterial wilt disease is a bacterial infection spread by cucumber beetles.

When the beetles wake up in spring after overwintering they start to feed on the leaves of your cucumber plants.

The bacteria that causes bacterial wilt (Erwinia tracheiphila) passes from the stomach of the beetles into your plants. Where it multiplies rapidly, blocking up the vascular system and causing them to wilt.

Eventually, the entire vine dies. And with it, any chance of a cucumber yield.

Look for plants that appear to be wilting, even though you’ve watered them. Other visible symptoms at the start of the infection include the leaves turning yellow and dry. Before turning brown later on.

There are 2 good ways to confirm a bacterial wilt infection.

Firstly, see if you can find the beetles. They have a distinctive bright yellow color. And come in 2 different types, with black spots or stripes.

Another good way is to cut off one of the infected stems and squeeze it. If a slimy, sticky ooze comes out then it’s most probably bacterial wilt.

There’s no effective way to cure the plants once the infection takes hold, so it’s important to control the cucumber beetles to prevent early death.

Row covers can keep the bugs away from your cucumber plants until they start to bloom.

And if necessary, you can use an insecticide that’s recommended for use on cukes.

Other ways of managing the situation include planting cucumber varieties that have resistance to bacterial wilt.

And staggering the planting of seeds throughout the spring and summer so new plants are continuously growing to replace those that die.

Cold Temperatures

Cucumber plants are negatively affected by the cold.

If the night time temperatures drop under 50°F then it’s common to see the plants start to wilt, with the leaves turning brown.

And extended periods below 60°F can also cause similar problems.

So it’s important not to start planting your cucumbers before temperatures have warmed up sufficiently.

The Squash Bug

Squash bug

Adult squash bug on a leaf

You’ll usually see the squash bug (Anasa tristis) feeding on summer squash plants and pumpkins. But you can also find it on cucumbers, especially if you’re growing them nearby.

They feed on the leaves on the plant, sucking out the sap from inside. With the most damage done to seedlings and younger plants that can’t withstand their attacks as well as more mature plants

You’ll notice your plants starting to wilt. And examination of the leaves will show yellow spots where they’ve been feeding, that later turn brown.

But to confirm them as the cause, you’ll need to find the bugs. Fortunately, they’re simple to identify.

The adults have a gray/brown body with stripes on the edges. And they grow to about ⅝ inches in size. The nymphs grow to ½ an inch and are gray.

They’re usually active between May and September.

It’s important to find them early, because once you have a larger infestation they’re very difficult to get rid of.

Checking your plants regularly and hand-picking them when you find them can work to keep numbers down.

If you need something more to deal with the problem then consider using neem oil or a horticultural soap.

Phytophthora Blight

Phytophthora leaf blight

Phytophthora blight of a taro leaf

Phytophthora blight (Phytophthora capsici) is another pathogen that more commonly affects squash and pumpkins. But it’s known to cause problems for all cucurbits, including cucumber plants.

It’s caused by a fungus that infects every part of the plant. As the disease progresses, it starts to lose its roots and becomes easy to pull out of the soil. And eventually, it completely collapses.

In the early stages, you’ll often see wilting of the leaves, and the development of large brown spots. You may also notice white mold growth.

It’s difficult to save infected plants, so it’s usually best to remove them from your garden.

You can also try fungicide sprays such as Ridomil Gold SL to prevent it from happening. But they won’t save your plant.

Squash Vine Borer

Squash Vine Borer

Adult squash vine borer photo by Lisa Brown

As the name suggests, the squash vine borer (Melittia cucurbitae) is most commonly seen on summer squash plants.

But it’s also occasionally found on cucumber plants.

You’ll recognize the adult insects by their wasp-like appearance, with a bright orange abdomen and black dots.

But it’s the large cream or white-colored larvae that cause the problem. They bore into the stem and feed on the insides, blocking water from flowing around the plant. You’ll see yellowing and wilting of the leaves. And eventually, the plants will die.

Once the larvae bore their way into the plant stem it’s difficult to treat them. So prevention is the best choice.

You can use pesticides such as carbaryl, bifenthrin, and permethrin, after you confirm the presence of squash vine borers in your garden. Try spraying or dusting the stems at the base to keep them from affecting the plants.

Overwatering

Overwatering cucumber plants, or planting them in poorly draining soil can also lead to wilting.

Cucumbers don’t like being sat in waterlogged and oxygen-deficient soil.

If you’re growing in containers, make sure they have good drainage holes in the bottom.

Underwatering

Although you need to be careful not to overwater, it’s also essential not to underwater.

Cucumber plants need a lot of water. And you’ll see them wilting in the sun if you don’t give them enough

If the top inch of soil feels dry then it’s time to give them some more. Water them 1-2 times per week. Make sure that you provide enough to saturate the top 8 inches of the soil where most of the roots are.

Cucumber plants require about 1-2 inches of water per week for healthy growth.

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