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17 Common Diseases of Leafy Vegetables: Photos, Prevention, and Treatment

Fredrick is an expert gardener, plumber, and author of farming guides. He loves to write about pest control, fish farming, and beekeeping.

Here are 17 common diseases of leafy vegetables that you want to prevent and protect against.

Here are 17 common diseases of leafy vegetables that you want to prevent and protect against.

Vegetable Devastation

Diseases of leafy vegetables can cause devastating effects to your crop. They can completely kill your crop or significantly reduce its quality, which means that you can incur great losses if one of the diseases strikes your garden.

What Are Leafy Vegetables?

Just in case you didn't know, leafy vegetables refer to crops such as collard greens, kale, cabbage, spinach, broccoli, rape, cauliflower, lettuce, celery, and turnip among others. They belong to the family Cruciferae.

Deadly Diseases

There are several diseases that attack leafy vegetables, and they are majorly caused by fungi, bacteria, or viruses. If you grow greens or are planning to grow them, here are the common diseases of leaf vegetables, their causes, prevention, control, and treatment. See clear vegetable disease photos in order to exactly diagnose the problem with your crop!

What Are the Common Diseases of Leafy Vegetables?

  1. Downy Mildew
  2. Alternaria Leaf Spot
  3. Frogeye Leaf Spot
  4. White Spot
  5. Powdery Mildew
  6. Anthracnose
  7. Wirestem
  8. Bottom Rot
  9. Damping-Off
  10. Blackleg
  11. White Rust
  12. Bacterial Soft Rot
  13. Yellows
  14. Clubroot
  15. Black Rot
  16. Mosaic
  17. Root Nematode

1. Downy Mildew - The Most Common Disease

Downy mildew is a fungal disease caused by Peronospora parasitica. It causes white mold and faint yellow spots on the dorsal and ventral sides of the leaves respectively.

The fungus thrives in cold and wet conditions, so you can prevent it by avoiding these conditions in your garden. Some practices that can cause cold and wet conditions are excess watering and over-head irrigation.

You can control downy mildew by uprooting the infected crop and burning it, and you can treat it by using the fosetyl-al fungicide.

2. Alternaria Leaf Spot

Alternaria leaf spot is caused by fungus Alternaria brassicae. The leaves of the infected crop (especially kales) have black or brown circular spots. With time, the spots enlarge and concentric rings appear on them.

You can prevent this disease by planting certified seed or disease-free transplants. You can also prevent it by avoiding wet and warm conditions in your garden as the fungus is very active under these conditions. Cruciferae weeds harbor the fungus, so you should eradicate them from your garden.

The best way to control Alternaria leaf spot is to uproot and bury or burn the infected crop. You can also spray your crops with a suitable fungicide immediately after you see the symptoms.

3. Frogeye Leaf Spot

Brought about by fungus Cercospora brassicicola, Frogeye leaf spot causes pale green, gray, or white spots on the leaves. The spots are bordered by a brown ring and can take any shape.

You can prevent this disease by planting fungus-free seed or transplants. Another great way to prevent the fungus is to improve soil drainage and avoid excess moisture in the garden. In addition, you can prevent it by doing proper weeding and crop residue removal.

You can control frogeye leaf spot by practicing crop rotation. Some copper products and fungicides like Benomyl can treat and control the disease. Use these chemicals immediately after you see the symptoms.

4. White Spot

White spot is a leafy vegetable disease caused by fungus Pseudocercosporella capsellae. The crop infected by the fungi usually has brown or gray spots on the leaves. The leaves later turn yellow and fall off within a few days.

The fungus can survive on seeds, so you can prevent it by planting certified seed. You can also prevent the harmful microorganisms by avoiding cool and damp conditions in your garden.

The best way to control white spot is to eradicate the infected crop. The disease spreads fast, so you should remove the sick crop immediately after seeing the symptoms. The fungus can be killed by suitable fungicides and copper products, which means that you can these chemicals to treat your infected crops.


White spot was a major problem in my garden until I discovered this copper fungicide. It amazes me on how it clears out the disease in less than a week.

Even when the crops are heavily infected, this organic farming-friendly fungicide does the job of killing the harmful micro-organisms, reviving your crops, keeping your garden free from fungus and increasing your yield!

And the best thing about it is that it can deal with other fungal diseases mentioned in this article, including the downy mildew and alternaria leaf spot.

I would recommend that you get it if you have the fungal menace in your garden!

White spot

White spot

5. Bacterial Soft Rot

Bacterial soft rot is caused by Erwinia carotovora, and it's one of the most common cabbage and collard green diseases. It causes dark, mushy patches on the stems and leaf stalks.

You can prevent bacterial soft rot by avoiding water-splashing in your garden. Farm tools can introduce the bacterium to your garden, so you should disinfect your tools before using them in your garden.

The best way to control the spread of the bacteria is to uproot and destroy the infected crop. Concerning treatment, you can use a suitable bactericide to kill the harmful microorganism.

6. Powdery Mildew

Powdery Mildew is a fungal vegetable disease caused by Erysiphe polygoni. It causes white powdery mold on the upper surface of leaves.

The fungus survives in cool and dry conditions, so you can avoid these conditions in order to discourage the pathogen from developing in your garden.

Powdery mildew can be treated with sulfur, so you can use the chemical on your vegetables when you notice the disease symptoms. As for the control, you can eradicate the infected crops to stop the spread of the pathogen.

7. Anthracnose

Caused by fungus Colletotrichum higginisianum, Anthracnose affects leaves & stems of vegetables like turnips, and causes small, gray, or black spots on these parts.

The harmful microorganism survives in weeds, so you can prevent it by removing any unwanted plants from your garden. You can also prevent the fungus by keeping your garden at a lower moisture level.

The affected crops can spread Anthracnose to the healthy ones, so you need to remove the infected crops from your garden in order to control the spread of the disease. You can try suitable fungicides to kill the pathogen.

8. Wirestem

Wirestem is caused by fungus Rhizoctonia solani which lives in the soil. The disease is recognized by reddish-brown patches on stems of leafy vegetables. The stem rots and peels off with time, exposing a wire-like wood.

The infectious microorganism is favored by moist soils and rotten plant remains. This means that you can prevent the disease by keeping your soil at the optimum moisture. If you have plant remains in your garden, dispose them to prevent the microorganism further.

The best way to control wirestem is to disinfect your soil. You can also control the disease by discarding any infected seedlings. The pathogen can be killed by fungicides that contain pentachloronitobenzene.

9. Bottom Rot

Caused by fungus Rhizoctonia solani, Bottom rot makes the lower leaves of the infected vegetables to turn black and wilt. The pathogen can move to the roots, causing root rot.

You can prevent this disease by disinfecting soil and planting materials. The infectious microorganism survives in a very wet soil, so you can do away with excess moisture to prevent it in your garden.

Bottom rot can be controlled by crop rotation, so ensure you do not grow leafy vegetables repeatedly in the garden when it strikes. In the case of treatment, you can use fungicides like Terraclor to cure the sick crops.

10. Damping-Off

Damping-off is another leafy vegetable disease caused by Rhizoctonia solani. It is also caused by Fusarium spp or Pythium spp. The fungus causes decay and wilt in seeds and seedlings respectively. The infected seedlings have light brown stems.

The pathogen survives is cold and wet soils, so you need to keep the soil temperature and moisture at optimum levels to prevent the occurrence of this disease in your garden. You need also to use certified seeds.

You should immediately disinfect your soil if you notice any symptoms of the infection. You should also dispose any infected seeds or seedlings. In addition, you can use Terraclor or any other suitable fungicide to treat the infected crops.



11. Blackleg

Blackleg is brought about by Leptosphaeria maculans which is a fungus that causes small, light brown spots on the stems. The spots are usually sunken and can enlarge, making the stem to deteriorate.

You can prevent the fungus by using certified disease-free seed. The microorganism is active in a wet soil, so you can prevent it by avoiding wetness in your garden.

You can use fungicides such as Thiram and Captan to treat vegetables infected by blackleg. If the infected crops do not respond to the treatment, uproot and burn or bury them in a dry soil.

12. White Rust

Caused by Albugo candida. White rust is a fungal disease recognized by yellow-white spots on the leaves and sometimes on the stems of greens.

You can prevent Albugo by disposing crop refuse before planting your crop. You should not allow cruciferous weeds to grow in your garden as they harbor the infectious microorganism.

The best way to control white rust is to practice crop rotation. This cultivation method prevents the buildup of the pathogen with seasons. Concerning treatment, you can try any suitable fungicide to kill the microorganisms.

13. Yellows

Yellows is a fungal disease caused by Fusarium oxysporum con-glutinans, and triggers formation of large, dull yellowish green patches on the leaves of vegetables.

The harmful microorganism survives in warm conditions, which means that you can prevent it by keeping your garden at lower temperatures. The disease can be spread by farm tools, so ensure you clean and disinfect your tools before using them in your garden.

The best way to control yellows is to plant certified seed or disease-free seedlings. You can try to kill the pathogen with fungicides such as Terraclor, Captan, and Thiram.



14. Clubroot

Clubroot is brought about by fungus Plasmodiophora brassicae, and causes leaves of the infected vegetable crop to turn yellow or pale green. The pathogen spreads to the stem and roots, causing club-like swellings on them.

You can prevent this disease by planting pathogen-free seedlings. The infectious microorganisms can be introduced to your garden by infested irrigation water and soil, so ensure your irrigation water is clean and your farm tools do not have soil particles from other gardens.

The plant sickness can be eliminated by fungicides such as Terraclor, so you can try them if your vegetables are infected. Concerning control, you can minimize the spread of clubroot by removing weeds that harbor it.

15. Black Rot

Black rot is caused by both fungi and bacteria (Xanthromonas campestris). It brings about yellow patches on the leaves of the infected crop. With time, the patches turn brown. The pathogen spreads to the veins and midribs of leaves and the stem, making them black.

The harmful microorganism can be introduced to your garden by contaminated equipment, irrigation water or plant materials. You can therefore prevent it by ensuring that anything you bring to your garden is disease-free.

You can control black rot by removing any infected crop from your garden. You can also practice crop rotation to prevent the buildup of the disease with seasons.


When it comes to bacterial leafy vegetable diseases, there is only one garden disease control concentrate that treats and cures the crops effectively. This is the Ortho Max which is the most trusted concentrate for all bacterial diseases that affect not only leafy vegetables, but also other garden crops and plants.

In my garden, I have had only one incidence of bacterial infection, and it was dealt completely by this concentrate. Never to come back! It can treat fungus too, but I would recommend that you leave that for the copper solution mentioned above.

If you think your garden has black rot, soft rot, or any other bacterial disease, I would advise you not to hesitate to buy this concentrate.

16. Mosaic

Mosaic is a viral disease caused by Turnip Mosaic, and it causes dark lines on the leaf veins of the infected crop. The leaves can become discolored with time.

The disease is transmitted by aphids, so you can prevent it by controlling the insects in your garden. Another way to prevent the virus is to keep your garden free from weeds.

The best way to control mosaic is to uproot and bury or burn the infected crops. Crop rotation can also help with the virus.



17. Root Nematode

This is a Meloidogyne incognita nematode that causes knots on the roots of vegetables. The infected crop becomes stunted and can wilt with time.

The nematodes thrive in a warm soil, so you can prevent them by keeping your soil at lower temperatures.

The infectious organisms can survive in the soil for many years. If you think your soil has these nematodes, you can fumigate it to control them. You can also control them by practicing crop rotation.

In Conclusion...

Leafy vegetable diseases are many, but these are the most common ones. You can easily prevent, control and treat them with the help of the information provided in this article. If there is a disease that you can’t control or treat, you can get assistance from a plant pathologist, botanist or agricultural extension officer.