It is pretty common for cabbage plant leaves to have spots on them. These spots can be due to several reasons and may or may not be treatable. So, how do you stop the spots from appearing when you cannot treat them?
Cabbage plants can have brown, white, black, and yellow spots that indicate diseases due to fungus, viruses, and bacteria. You may be able to control the spread if you catch the infection in time. So, you must take preventative measures before the damage begins.
The appearance of spots can cause significant damage to the plants. The leaves can get spots even during storage. Read on to see why these spots appear and how to control and prevent them.
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Why Do Cabbage Leaves Get Spots?
The spots on the cabbage plant can appear in different ways. Some leaves turn brown at the edges, while others get marks all over them.
Let’s see the various reasons that cause these spots to appear:
- Spots due to fungal infections.
- Spots due to viral infections.
- Spots due to bacterial infections.
Fungal Cabbage Plant Spots
Fungal diseases can cause spots and are very common among cabbage plants. They usually prefer damp and warm conditions and are not treatable.
Let’s see some of the more severe conditions:
Alternaria is one of the most common fungal infections in cabbage plants. The onset of the infection causes tiny brown and yellow dots on the leaves. The spots grow to create a target-like pattern, surrounded by a yellow ring or halo.
The disease can cause the entire leaf to turn yellow or brown with small holes, giving it a singed look.
Alternaria affects cabbage during warmer, moist conditions such as the rainy season. Older plants are more prone to the disease, which spreads in crowded fields or plant gardens.
Ring Spots Fungus
Black spots appear on leaves as the weather turns warm and damp. The cabbage plants can contract the disease in the garden, which gets worse in storage, where they get spots on leaves and stems. These ring-like spots have a yellow halo around them.
As the condition worsens, the spots grow and merge to the point where the entire plant appears black.
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This fungal disease causes chalky white spots on the leaves, which look like blisters. The spots, called sori, first appear on the leaf’s underside and spread from there.
The disease deforms the plants. White rust occurs when the conditions get warm and soggy.
Downy Mildew affects the cabbage leaf on both sides. It causes brown-yellowish spots on the top side and grayish-white mold on the underside of the leaf.
The fungus can attack the fully-grown cabbage plant. Its ion also attacks the young seedlings, killing them in most cases. The disease can occur when the weather conditions are humid and cool.
White Spots on Cabbage Leaves
The leaves develop white spots with light green or yellow rings around them. These dots appear in the shape of small circles and cause tiny holes in the leaves.
The discoloration of the leaf prevents chlorophyll formation. With no chlorophyll, the leaves turn yellow and eventually die.
Mature plants usually only lose their leaves and have a better chance of surviving. However, the disease is lethal for seedlings in most cases.
Like other fungal diseases, white spots prefer the rainy season’s cool and moist climate.
Blackleg is a terrible fungal disease for cabbages and other similar plants. On leaves, blackleg appears as gray spots with a yellowish halo, giving it a burnt look. The plants, in most cases, cannot survive blackleg.
The fungal disease favors moist and wet conditions.
Anthracnose develops during soggy weather, and the spots are brownish-black in color. As the season gets dry, the spots can turn grayish. The disease primarily affects older leaves and may leave the youngest ones alone.
The disease can affect the plant at the seed level and then grow from there.
Read: Why is my Corn Plant Leaves Curling?
Fungal Spots Control and Prevention
You cannot save, treat, or control chronic cases of fungal infections. However, you can keep the disease from spreading or prevent it.
- You must remove the damaged crops to prevent the spread. Moreover, remove all plant debris after harvesting to avoid infection.
- Avoid overhead watering of the plant head. Drip irrigation is a better option during their development and leaves enough space between two plants to allow air circulation.
- You can control the disease by spraying fungicides. Spray the plants with fungicides at regular intervals (after every 7 to 10 days), starting from the rainy season until it becomes dry.
- Use clean, certified, and healthy seeds. Do not take seeds from infected plants. These seeds may either spread the infection or may not grow at all.
- Do not let the weeds grow. An abundance of weeds can foster an environment for bacteria and fungus to grow.
- Rotate your cabbage with other plants for three years. It is best not to plant new cabbages after harvesting the affected plants. Rotate cabbages with crops not susceptible to fungal infections that attack cruciferous crops.
- Do not water the plants when you see any symptoms. You must control the moisture by letting the soil dry a bit.
- Clear away plant debris. Do not let any debris from infected plants stay behind after harvesting. It can affect new plants and spread diseases.
Viral Cabbage Plant Spots
Viral diseases are not good news for cabbage plant farmers. Once a virus affects the plant, there are no sprays or chemicals that can control the viral spread.
Some of the viral spots in the cabbage plant are as follows:
Turnip Mosaic Virus Spots
The virus causes ringlike spots on cabbage leaves, which look like mosaics. Leaves of mature cabbage plants get brown or yellowish spots. Turnip Mosaic Virus makes the plant look stunted or deformed.
Spots appear on the outer leaves of the cabbage and affect the entire plant. Turnip Mosaics can attack plants in the field or in storage (after harvesting). The stored cabbage has darker spots on its internal leaves. So, you can only see it when you cut the cabbage open.
Cauliflower Mosaic Virus Spots
As the name suggests, the virus mainly attacks cauliflowers and cabbages. The infected plants get necrotic spots, especially after storage. Some plant heads even get the spots at harvesting.
However, the disease is more damaging to plants in storage and can turn the leaves yellow.
It is more common in temperate regions such as California or Mississippi.
Have a look: Corn Plant Leaves Yellowing [How to Prevent]
Control and Treatment of Viral Spots
Treatment of viral spots is not possible. You can try and remove the affected plants at early detection. It may give you a chance to control the disease from spreading.
Your best chance at protecting your cabbage plants is by taking preventative measures such as:
- Plant healthy seeds.
- Clear the field completely if the older plants have an infection. Affected land or area can spread the virus to new plants.
- Leave some distance between cabbage rows so the air can flow better.
- Rotate the cabbage to avoid future infection.
- Use effective insecticides to prevent a viral attack.
Bacterial diseases can also cause different types of spots on cabbage leaves. Just like viral and fungal infections, bacterial conditions can also damage the crop and may not be treatable if detected in time.
Bacterial Leaf Spots
Bacterial leaf spots cause necrotic spots on cabbage leaves, leading to discoloration and even killing the leaf. The spots can be brown with yellow rings or blackish spots. It may even cause uneven color tone: light and dark spots on the leaf.
The disease can also affect leaf edges, causing leaf tissue dryness and breakage. The spots mostly appear on mature leaves but can also spread to young foliage.
Black Rot Spots
Cabbage plants get black rot due to infected seeds or bacteria entering the leaves. The onset of the disease marks the yellowing of leaf edges. The discoloration then turns into lesion-like spots, and the progression of black rot results in head rot and black vascular tissue.
Cabbage can get black rot in the garden and at any growth stage after maturation. The bacterial condition usually surfaces during hot and humid weather conditions. It can start as early as Spring and spread quickly in the summer.
Control and Treatment of Bacterial Spots
You can save the plants if you catch bacterial diseases early on. The treatment for all the conditions is almost the same.
- You can remove the infected plants. This can save the rest of the plants and restrict the spread.
- Do not touch the healthy plants if you work with the infected ones. Wash your hands first; otherwise, you can spread diseases to your new plants.
- Use healthy seeds for planting new cabbages. Using old seeds from infected plants can damage the new ones.
- Avoid overhead irrigation. You can protect the plants by avoiding overhead watering and choosing drip irrigation.
- Halt watering if the soil is too damp. Wait for the moisture to evaporate before watering the cabbage plants.
- The cabbage rows must have enough space between them. It allows better air circulation, which can prevent dampness and rot.
- Do not leave plant debris in the field. You must clear the land of plant debris after harvesting cabbages. Otherwise, the waste can affect new plants.
- Do not plant seeds if the land has poor drainage. Otherwise, the soil can retain water, and the moisture content can encourage the spreading of bacterial diseases.
- Use pesticides regularly to keep bacteria away. It can protect the new plants.
Furthermore, you may like some more gardening articles:
- Corn Plant Leaves Turning Brown [Reasons & Preventions]
- How to Save a Dying Corn Plant
- Why Are My Cabbage Leaves Turning Yellow?
- Why Are My Cabbage Leaves Turning Purple?
- Homemade Bug Spray for Cabbage Plants
Most of the cabbage leaf spots appear due to warm and damp conditions. You may not be able to treat or stop the spread, but you can take preventative measures before planting the seeds.
I’m Elsa, and I love gardening. I started GardeningElsa.com as a resource for other gardeners, and I offer expert advice on gardening topics such as plants, flowers, herbs, and vegetable gardening. On my website, I share my latest tips and tricks for creating beautiful gardens. When I’m not working on my website, you can find me in my own garden, tending to my plants and flowers. Read more about me.