Open main menu

Brussel Sprouts pests and diseases

Published: 09.04.2023
pest/disease type symptoms on Brussel sprouts control/prevention
Aphids Pest Tiny, pear-shaped insects clustered on new growth and undersides of leaves; sticky residue on leaves Insecticidal soap or neem oil spray; Introduce natural predators such as ladybugs or lacewings; Plant companion plants that naturally repel aphids like garlic, chives, or mint
Cabbage loopers Pest Green caterpillars that chew on leaves and leave behind irregular holes Handpick and remove caterpillars; Apply Bacillus thuringiensis (Bt) spray; Cover plants with row covers
Cabbage maggots Pest Larvae feed on roots causing stunted growth, yellowing leaves Cover soil with row covers before planting; Practice crop rotation; Apply parasitic nematodes or beneficial insects like rove beetles
Flea beetles Pest Small, black beetles that jump when disturbed; tiny round holes on leaves Apply organic pesticides like pyrethrin or neem oil; Surround plants with reflective mulch or aluminum foil to deter beetles; Plant companion plants like radishes or onions to repel beetles
Clubroot Disease Swollen, distorted roots; yellowing leaves; stunted growth Practice crop rotation; Plant resistant varieties; Amend soil with lime or wood ashes to raise pH levels; Avoid planting in overly wet soil
Black rot Disease Yellowing leaves that turn brown and develop blackened veins; V-shaped lesions on leaves; foul odor Remove and destroy infected plants; Practice crop rotation; Avoid overhead watering; Apply copper-based fungicides
Downy mildew Disease Yellowing leaves with white, gray, or purple mold on undersides; stunted growth Avoid overhead watering; Increase air circulation around plants; Apply fungicides like copper hydroxide or potassium bicarbonate
Powdery mildew Disease Powdery white or gray mold on leaves; yellowing leaves Increase air circulation around plants; Water in the morning to prevent excess moisture; Apply fungicides like neem oil or potassium bicarbonate
Root knot nematodes Pest Swollen, knotted roots; yellowing leaves; stunted growth Practice crop rotation; Plant resistant varieties; Apply beneficial nematodes; Solarize soil before planting by covering with clear plastic for several weeks to kill nematodes.


Aphids are tiny, soft-bodied insects that feed on the sap of plants. They are a common pest of Brussel sprouts and can quickly multiply, causing damage to the leaves and stunting growth.


The first signs of an aphid infestation are small, green or black insects clustered on the undersides of leaves. They can also be found on stems and buds. As they feed, they secrete a sticky substance called honeydew, which can attract other pests like ants and cause fungal growth. Leaves may become distorted and yellowed, and the plant may not produce as many sprouts as it should.

Control or Prevention:

There are several ways to control or prevent an aphid infestation in your Brussel sprouts:

  • Blast them off with a strong stream of water from a hose.
  • Introduce natural predators like ladybugs, lacewings, or parasitic wasps.
  • Apply insecticidal soap or neem oil to affected plants.
  • Keep your garden free of weeds, which can attract aphids.

Preventing aphids from infesting your Brussel sprouts is key to keeping them healthy and productive. Regularly inspect your plants for signs of pests and take action immediately if you spot any. With proper care, your Brussel sprouts can thrive and produce a bountiful harvest.

Cabbage Loopers

Cabbage loopers are common pests that attack not only cabbage but also other brassica plants like Brussels sprouts. These small, green-colored larvae feed on the leaves of the plant, causing significant damage to the foliage. In this section, we'll discuss how to identify cabbage loopers, their symptoms, and ways to control or prevent an infestation.


The primary symptom of cabbage loopers is the presence of irregular holes in the leaves of the plant. You may also notice fecal matter, which looks like black specks on the foliage. In severe cases, the plants may become stunted, and the leaves may turn yellow and wilt.

Control or Prevention

One of the most effective ways to control cabbage loopers is by introducing natural predators like birds or wasps that feed on the larvae. Additionally, you can try handpicking the larvae off the plant or spraying them with Bacillus thuringiensis (BT), a natural insecticide that specifically targets cabbage loopers.

Preventing an infestation is also possible by practicing good sanitation and crop rotation. Removing any debris or fallen leaves from around the plant and not planting brassica plants in the same location for at least two years can help prevent cabbage loopers from establishing themselves in your garden.

In conclusion, cabbage loopers are a common pest that can cause significant damage to your Brussels sprouts and other brassica plants. By identifying the symptoms early and implementing control or prevention measures, you can protect your plants from these pesky pests.

Cabbage Maggots

Cabbage maggots are common pests that affect a wide range of plants, including Brussel sprouts. The adult flies of the cabbage maggot are small and grayish in color, resembling small houseflies. They lay their eggs near the base of the plants, and the larvae that hatch from the eggs feed on the roots of the plants, causing significant damage.


One of the most obvious symptoms of cabbage maggot infestation is wilting and yellowing of the plants, which eventually leads to stunted growth or death. You may also notice small tunnels or holes in the roots when you pull up affected plants.

Control and Prevention

There are several ways to control and prevent cabbage maggots from damaging your Brussel sprouts. One effective method is to use row covers, which can prevent adult flies from laying eggs on the plants. You can also try companion planting with plants that repel cabbage maggots, such as mint, thyme, and rosemary. Insecticides are also available for more severe infestations, but be sure to read and follow all label instructions carefully.

Regular crop rotation can also help to prevent cabbage maggots from becoming a problem in your garden. Avoid planting Brassica family plants in the same area for more than two years in a row. By following these prevention and control methods, you can keep your Brussel sprouts healthy and free from cabbage maggot damage.

Flea Beetles

Flea beetles are a common pest that attacks Brussel sprouts plants, as well as other plants in the cabbage family. These small, black or brown beetles are only about 1/10 inch long, but they can cause significant damage to plants.


The first sign of flea beetle damage is small holes in the leaves of the plant. As the infestation gets worse, the leaves may turn yellow and eventually die off. In severe cases, the damage can cause stunted growth and even death of the plant.

Control or Prevention

There are a few steps you can take to prevent flea beetle infestations. First, make sure to rotate your crops every year. This will help prevent any pests or diseases from building up in the soil. You can also cover your plants with row covers to keep the beetles from getting to them.

If you do have an infestation, there are a few things you can do to control it. One option is to spray your plants with insecticidal soap or neem oil. Another option is to use sticky traps to catch the beetles.

Overall, flea beetles can be a frustrating pest to deal with, but with a little prevention and control, you can keep them from damaging your Brussel sprouts plants.


Clubroot is a soil-borne disease that can affect a wide range of plants, including Brussel Sprouts. It is caused by the fungus Plasmodiophora brassicae and can lead to stunted growth, yellowing leaves, and wilting.

Symptoms of clubroot in Brussel Sprouts include the formation of swollen, misshapen roots, which can make it difficult for the plant to take up water and nutrients. Infected plants may also appear stunted or wilted and may have yellowing leaves.

To prevent clubroot, it is important to avoid planting susceptible crops in areas where the disease has been present before. Rotating crops and improving soil drainage can also help reduce the risk of infection.

If clubroot is present in your garden, infected plants should be removed and destroyed immediately to prevent the spread of the disease. Avoid planting Brassica crops in that area for at least three years, as the spores can remain in the soil for several years.

In conclusion, clubroot is a serious disease that can affect Brussel Sprouts and other Brassica crops. Preventing its spread by practicing good crop rotation and soil management techniques is key to maintaining a healthy garden.

Black Rot

Black rot is a common disease that affects Brussel sprouts and other cruciferous vegetables. It is caused by the fungus Xanthomonas campestris and can result in significant yield losses if not managed effectively.


The symptoms of black rot initially appear as small, water-soaked lesions on the leaves of the plant. As the disease progresses, these lesions turn black and expand rapidly. The veins of the leaves also turn black, and the affected leaves may drop off the plant. The sprouts themselves may develop black spots or streaks, become stunted or distorted, and have a bitter taste.

Control and Prevention

The best way to prevent black rot is to practice good sanitation in the garden. This means removing infected plant debris, rotating crops, and avoiding planting cruciferous vegetables in the same location for several years. Additionally, it is important to avoid overhead watering which can spread the disease. In case of infection, remove infected plant parts immediately and dispose of them away from the garden. Fungicides can also be used to control black rot.

Overall, preventing and managing black rot requires diligence and good gardening practices. By following these steps, beginning gardeners can help keep their Brussel sprouts healthy and productive.

Downy Mildew

Downy mildew is a common disease that affects Brussels sprouts, among other plants. It is caused by the fungus-like organism, Peronospora destructor, and thrives in cool, damp conditions.

Symptoms: The first signs of downy mildew are yellowing leaves and the appearance of white or gray patches on the undersides of the leaves. As the disease progresses, these patches turn brown and fuzzy, and the leaves may start to curl or wilt. Eventually, the plant may die.

Prevention and Control: To prevent downy mildew, avoid overhead watering and allow for proper air circulation by spacing plants appropriately. If you suspect downy mildew, remove and destroy any infected plant material immediately. Use fungicides containing copper or sulfur to treat the disease, following package instructions carefully.

In addition to fungicides, you can take other preventative measures such as rotating your crops annually and using disease-resistant cultivars. A healthy soil with good drainage can also help prevent downy mildew from taking hold.

By being vigilant and taking appropriate action, you can prevent or control downy mildew in your Brussels sprouts crop and enjoy a healthy harvest.

Powdery Mildew

Powdery mildew is a common fungal disease that affects many types of plants, including Brussel sprouts. It is caused by a group of fungi that create a white, powdery coating on the leaves, stems, and flowers of infected plants. This coating can make the leaves look as if they have been dusted with flour or talcum powder.

Symptoms of powdery mildew on Brussel sprouts include white or grayish spots on the leaves, which may turn yellow or brown and dry out as the disease progresses. The spots can merge together and form a dense coating that covers the entire plant. Infected plants may also experience stunted growth, reduced yields, and decreased quality of the sprouts.

To prevent powdery mildew, make sure to plant your Brussel sprouts in an area with good air circulation and plenty of sunlight. Avoid overhead watering, which can create humid conditions that encourage the growth of the fungus. If you notice signs of powdery mildew on your plants, remove infected leaves and dispose of them in the trash (not compost). You can also use fungicidal sprays or sulfur dust to help control the disease.

Root Knot Nematodes

Root knot nematodes are microscopic worms that can cause serious damage to the roots of your Brussels sprouts plants. These pests feed on the roots, causing them to swell and form knotty galls. This damage can lead to stunted growth, wilting, and even death of the plant.

Symptoms of root knot nematodes include yellowing leaves, stunted growth, and the presence of knotty galls on the roots. These nematodes can be introduced to your garden through infected soil or plant material, so it is important to take preventative measures to avoid their spread.

To control root knot nematodes, you can use soil solarization, which involves covering the soil with clear plastic to trap heat and kill off any pests. Crop rotation is also an effective method, as nematodes tend to be specific to certain crops. You can also use organic soil amendments, such as compost or aged manure, to promote healthy soil and root development.

Prevention is key when it comes to root knot nematodes. Avoid planting Brussels sprouts in soil that has been previously infected with nematodes and use disease-free plant material. Regular soil testing can also help identify any potential issues before they become a problem. By taking proactive steps, you can protect your Brussels sprouts plants from these destructive pests.

Author: Michael Chen
Bio: I'm gardening specialist with a mission to empower people to grow their own fruits and vegetables. With my background in Plant Science from the University of California and experience working with farmers and community gardens, I'm dedicated to promoting sustainable agriculture practices and helping individuals achieve bountiful harvests. Let's get growing!