A Rundown of Broccoli Worms, Pests and Diseases

Last update: November 17, 2020

Insects and disease can destroy many types of plants. Broccoli plants have big, delicious leaves that grow from the stems and attract worms and other insects that feed off them. Some of these pest infestations can be treated easily with an organic insecticide, but others can destroy your broccoli quickly.

To prevent disease, like club root and bacterial soft rot, do not plant broccoli in the same spot for at least two years. Keep soil temperatures cool and water in the morning. Growing your own broccoli from seeds can also prevent contaminations.

Common Broccoli Worms

Cutworms and cabbage worms are the most common types to harm broccoli plants. Cutworms are a type of caterpillar that feed on broccoli and other plants.

broccoli worms, pests and diseases

They like to eat the stems of broccoli plants closest to the ground, which weakens the rest of the plant and kills it. If your plants look like they’ve been cut at the base, the most likely culprit is cutworms.

Cabbage worms are the larvae of moths and butterflies. They feed on all stages of broccoli plants and can prevent the plants from forming heads, rendering them useless.

Cabbage worms can be green or a bluish-gray with black stripes. If you have a cabbage worm infestation, you’ll usually notice small holes in the leaves where they feed. This video from Midwest Gardener shows the damage caused by cabbage worms:


Cutworms typically feed in gardens with dead plant material, since this is where they lay their eggs. Keeping your soil clean is one of the most important things you can do to prevent an infestation of cutworms. You can also rotate your crops each year by planting in a new location from the previous year. Your new crop won’t be affected by any problems with last year’s soil.

Additionally, you can create a collar to put around the stems of your broccoli plants so cutworms can’t gain access. A toilet paper roll works well for this, or you can cover the stems with some aluminum foil.

Cabbage worms must be taken care of as early as possible before they become a serious problem. This means continuously checking your broccoli plants for signs of larvae or mature cabbage worm butterflies near the garden.

Floating row covers can be very helpful in keeping adult butterflies from laying eggs, since they usually lay them on the broccoli plant leaves. You might also want to use Bacillus Thuringiensis, a natural bacterial insecticide, to treat cabbage worms by spraying your broccoli plants.

Common Broccoli Pests

Broccoli plants can also come under attack by other pests, like aphids and flea beetles. Because of their resemblance to head lice, they are also known as plant lice. However, they come in several colors, including green, orange, and brown, which can make them difficult to spot in your garden.

Aphids feed on plant sap that they remove from the underside of leaves. If you notice only a few of them, you can pick them off with your fingers. But, aphids are usually unnoticeable until you have a full infestation, which is possible if you see your leaves turning brown or wilting.

Flea beetles are tiny and can also be difficult to see on broccoli plants. You may notice small holes on your plant leaves, which is what they feed on. Flea beetles don’t usually kill your broccoli plants unless you have a large infestation, but they can do enough damage to harm the productivity of your broccoli plants.


For small aphid infestations, pick the bugs off leaves or use a steady stream of water from your hose to rinse them off. For larger infestations, you may need to use an insecticide. An organic insecticidal soap can help treat and prevent further infestation. It’s also safe to ingest, so harvesting and eating your broccoli the same day will not harm you.

You can prevent flea beetles from bothering your broccoli plants by adding a thick layer of mulch on top of the soil. This will keep adult flea beetles from coming up from the soil when they change from larvae. You can prevent an infestation next year by thoroughly cleaning your soil from weeds and plant debris and rotating your broccoli plants.

Common Broccoli Diseases

Broccoli is very susceptible to disease, mostly because it requires very clean soil and a lot of water, which can cause root rotting and fungal growth within the soil. Two common diseases to watch for in broccoli plants are club root and bacterial soft rot.

Club root is, perhaps, the easiest disease for your broccoli to be affected by. It’s caused by a bacterium within the soil, and usually comes from plants from another source, rather than those you grow from seed yourself. Club root causes a thick, firm mass of tangled roots that lead to wilted leaves and a dying plant.

Bacterial soft rot occurs when soil conditions become too warm. Broccoli is a cool-weather crop and needs cool soil to thrive. Broccoli feeds with plenty of water, and excess water and warm soil can lead to extreme fungal conditions that produce bacterial soft rot. If your plants have this disease, you may notice a sunken, darker spot in the center of your main broccoli head. Eventually, the full head will look like the center.


The best prevention for many broccoli plant diseases is rotating your crops each season and taking excellent care of your soil. For further safety, begin your own crops from seed rather than purchase them from another source.

To lower the risk of club root, you can add lime to acidic soil at least two months before you plant your broccoli. Make sure your garden beds are clean and the soil is in excellent condition. If you’re worried about plants from previous years affecting your newest crop, begin with all new soil.

To avoid bacterial soft rot, you can plant varieties of broccoli that grow dome-shaped heads to allow for better water drainage. Water your broccoli in the morning so they have the full day to dry in the sun.

Photo by makamuki0 licensed under CC0.

Comments (1)

Leave a Reply

Your email address will not be published. Required fields are marked *