5 Causes of Cucumber Leaves Turning Brown[Troubleshooting]

Cucumber is one of the most popular vegetables among the gardener because of its easy-to-grow nature. That doesn’t mean, there is no cucumber problem. Brown leaves of the cucumber are one of the most facing problems.

Don’t worry! The problem can be fixed easily. Before taking any action, you have to know what are the reasons behind it.

So, why are the cucumber leaves turning brown? 

Water Stress, Temperature Variations, Fungal Infection, Pest attack, and Bacterial Infection may be the reasons for the brown leaves of your cucumber.

And in this article, I’ve discussed the reasons with the most effective solutions. I hope this article helps you to get rid of the brown leaves of cucumber.

So, without further ado, let’s get started-

Why Are The Cucumber Leaves Turning Brown?

1. Water Stress of Cucumber

Cucumbers require a lot of water for their healthy growth. But overwatering or underwatering both can turn the green cucumber leaves into brown.

Because of the lack of water, the young leaves of cucumber are turning brown, dry, and crispy.

On the other hand, overwatering makes waterlogged conditions. So, the roots become unable to function properly. As a result, roots cannot uptake enough water and nutrients. Finally, the leaves turn brown.

Before coming to any conclusion it’s better to test the soil with a moisture meter (our pick: Atree 3-in-1 Soil Tester Kits with Moisture, Light, and PH Test for Garden). You can also dip a stick into the soil to see if it’s dry or moist.

Control Measure

Water your cucumbers at least 1-2 times per week. If you feel the topsoil is dry then water it lightly. 

If you’re growing in a container, then make sure it has good drainage holes. You can replant the cucumbers in a bigger container if the vines become too bushy. So, the roots will get more room to grow.

Avoid over-watering because the waterlogged condition also can develop fungal problems.

2. Temperature Effect on Cucumber

Cucumbers are tropical vines. They love warm and sunny weather, usually between 18-23° C. So, when the cold weather snaps cucumber leaves start showing symptoms. Leaves start turning brown at the edges. 

Even too high-temperature around 40-45°C can also turn the bottom leaves into brown.

Control Measure

Cucumber vines need some protection from the cold. In cold weather cover the cucumbers with any light materials or plastic sheets at night. Remove them in the morning.

And make sure you are providing enough water. Avoid planting cucumbers too early in the season.

3. Cucumber Pest Attack

Insect infestations are a common scenario in cucumber plants.

Four-lined Plant Bugs, Squash Bugs, Aphids, and Cucumber Beetles are the main pests that cause the browning of leaves. They feed on the leaves and make them susceptible to various diseases.

Quick Identification

Four-lined Plant Bugs can be easily identified. They have black stripes down their yellow-green wings. They feed on leaves and make brown sunken spots where they’ve fed. 

You can identify Squash bugs by the brown stripes they have on the edge of the dark brown abdomen.

They feed on cucumber leaves and make yellow spots that turn brown. They do the most damage on young cucumber plants and seedlings.

Aphids are very tiny insects. You’ll find them on the underside of cucumber leaves where they feed by sucking out the sap. Aphids usually feed in large groups.

As a result of their feeding, the cucumber leaves start to turn yellow. And eventually, turn brown and die.

Cucumber beetles are black striped with a yellow abdomen. They chew on the underside of leaves and eat away at the interior while leaving the upper side intact.

Control Measure

You need to pick the best insecticide for your plants that is equally safe and effective against pests(our pick: Monterey Garden Insecticide & Pesticide).

Also, Here are some amazing home remedies that can also be effective to solve pest problems-

#Recipe 1:-Horticultural Oil Recipe

  1. Mix 3 teaspoons of liquid soap with 1 cup of any oil like soybean oil, vegetable oil, sunflower oil, or mustard oil. Keep this mixture as a stock solution in a bottle.
  2. Then mix 4 teaspoons of this mixture with every cup of water and pour it into the sprayer. 
  3. Spray twice a week.

#Recipe 2:-Pepper Spray Recipe

  1. Take 2 liters of water in a pan and add 4 teaspoons of dry pepper to it. 
  2. Boil it for 15 minutes.
  3. Then let it aside for 24 hours so the pepper can infuse with water properly
  4. Strain the peppers with a fine cloth
  5. Add a few drops of liquid soap and it’s ready to go.
  6. But be cautious while spraying as it can give a burning sensation to the skin.

#Recipe 3:- Tomato Leaf Spray Recipe

  1. Chop a cup of tomato leaves and let them stay overnight in 250 ml of water. 
  2. Then strain out all the leaves and add another cup of water to dilute the solution. 
  3. Spray on the leaves twice a week. Tomato leaves have compounds that are toxic to insects but completely safe to plants and humans.

 #Recipe 4:-Garlic Spray Recipe

  1. Take 5 garlic cloves and 250 ml of water and blend them in a mixer-blender.
  2. Strain it with a strainer and add water to make it 2 liters of solution. You can store it in your fridge and spray it every week.

#Recipe 5:-Insecticidal Soap Spray

It’s the easiest one to make. Combine 5 teaspoons of liquid soap and 2 teaspoons of oil in 1 liter of water. 

Preventive Measure

Avoid excess fertilization of any nutrient especially Nitrogen because aphids attack high-nitrogenous leaves. 

4. Fungal Infections

Fungal infections are another common problem for gardeners to deal with. Quick identification and action can save the plant.

Alternaria Leaf Blight, Anthracnose, Downy Mildew, and Fusarium Wilt are the fungal infections that cause the browning of cucumber leaves:

Quick Identification

Alternaria leaf blight causes brown spots on mature leaves. They’re small at the beginning, but they grow into large irregular shapes with a yellow edge. The leaves eventually wilt, turn brown, and then die. 

Downy Mildew causes angular yellow spots on the leaves. But as the disease gets worse the leaves turn brown on the edges, dry out, and eventually, leaves fall from the plant. You will also find dark-purplish spots on the lower side of the leaves.

Anthracnose appears as yellow circles with dark brown edges that turn the whole leaf brown. 

Fusarium Wilt causes the young leaves of cucumber to change brown and later affects the older leaves and makes the plant dehydrated. 

Control Measure

Remove all the infected cucumber leaves and fruits and apply a proper fungicide. 

Select a fungicide that is non-toxic to the cucumbers but effective against fungal diseases. We recommend Bonide Copper  Fungicide.

Try these easy homemade recipes below for organic control:

#Recipe 1:-Cinnamon Spray Recipe

  1. Take 1 tablespoon of cinnamon powder in 500 ml of water and mix well. 
  2. Let it rest overnight and then strain with a fine cheesecloth and pour it into the sprayer. 
  3. Spray in the stem and leaves of the affected plant.

#Recipe 2:- Baking Soda Spray

  1. Take 1 teaspoon of baking soda
  2. Half a teaspoon of dishwashing liquid
  3. Half a teaspoon of oil 
  4. 1 liter of water 
  5. Mix these ingredients very well. Then pour it into the sprayer.

Preventive Measure

For severe infections, it’s sometimes best to get rid of the plant entirely and replace the soil.

Remove the infected plant or infected parts before they can do any further damage. Always disinfect garden tools with bleach. 

There is no cure for Verticillium wilt so if plants get affected by this you have to quickly remove the plants. 

5. Bacterial Infections

Angular Leaf Spots, Gummy Stem Blight, and Bacterial Wilt can turn the cucumber leaves brown.

Angular Leaf Spot is spread usually through insects. It causes small angular spots on the leaves that are dark brown with a yellow middle. The leaves become very dry and crispy, and eventually, fall out.

Gummy Stem Blight is a common disease that affects the entire plant and creates brown spots on the leaves including the edges.

The stems show black spots or brown lesions which also may ooze gummy fluids. This bacterial disease thrives during wet and warm weather.

Bacterial wilt is a common enemy of cucumbers. Especially to the variety of Lemon Cucumbers and Eureka Cucumbers.

Bacterial wilt starts with the yellowing of leaves. But, it quickly spreads around the plant and the cucumber leaves turn brown.

You can cut an infected leaf at the stem and put it in a glass of water. If milky sap comes out of it then it confirms bacterial wilt infection.

Control Measure

First, get rid of the infected plants and infected parts then spray the rest of the plants with a good bactericide (our pick: Monterey Ready to Use Fungicide & Bactericide). The copper spray also helps in the early stages 

Also, when you see harmful insects spray a good dose of insecticide.

Note: You can also try the home remedy recipes mentioned above. Especially the baking soda spray and insecticidal soap spray.

Preventive Measure

Always use Bacteria-free seeds. If you suspect that your plants are suffering from bacterial infection don’t plant cucumbers in that area the following year. 

Avoid planting cucumbers in the same place in the garden for multiple years in a row. Keep the growing area and garden tools clean. 

Always look out for harmful insects.


I have tried to provide all the necessary information about the brown leaves of cucumber and hope this article helped you to get a better insight on this topic.

Don’t wait! Look out for the symptoms and take the right action.

Don’t forget to share your experience with the brown leaves in the comments below.

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