Cabbage Pests » Top Tips on Identification and Control
Don’t Spread Your Cabbage Among Cabbage Pests
- 1 Don’t Spread Your Cabbage Among Cabbage Pests
- 2 How to Use Intercropping Wisely to Increase Your Harvest
- 3 Intercropping Must be Implemented with Care
- 4 Examples of Intercropping
- 5 How Intercropping Works
- 6 The Problems with Intercropping
- 7 How to Interplant Well
- 8 Conclusion
- 9 Brassica Pests & Diseases
- 10 • A List of Common Pests & Diseases • Basics of Prevention & Control • Further Resources
Cabbage attracts several pests, including aphids, flea beetles, cabbage maggots, and caterpillars from a variety of moths. Inspecting your cabbage for eggs, early appearances by the larva, and early signs of damage helps to catch infestations early and prevent serious damage. If your cabbage does become infested, though, organic treatments can control all of these pests.
Getting to Know the Pesky Intruders
The pests that attack cabbage include:
- Cabbage Loopers
- Diamondback Moth Caterpillars
- Imported Cabbageworms
- Cross-Striped Cabbageworms
- Beet Armyworms
- Flea Beetles
- Cabbage Aphids
- Cabbage Maggots
The Green Team: Cabbage Loopers, Diamondback Moth Caterpillars, and Imported Cabbageworms
These first three are green caterpillars, and they are sometimes lumped together as ”green worms.” They have distinguishing characteristics, though, and it can be important to know which species is attacking your cabbage.
Cabbage Looper Caterpillar
The cabbage looper caterpillar is a light yellow-green with four white stripes running down the length of its body, and it is so named because, like an inchworm, it has legs on its front and rear ends, but none in the middle. So, like an inchworm, when it crawls, the mid-section of its body arches up into a loop.
The cabbage looper moth has mottled, grayish-brown, 1-1/2 inch wings with a small, silvery, sock-like patch at the center of the upper wings. You’ll see these moths flying around at dusk.
Newly hatched caterpillars are most likely to be on the underside of the lower leaves, but as they grow they move to the center of the plant to feed between the veins of the leaves.
Diamondback Moth Caterpillar
The diamondback moth caterpillar is also yellow-green, but it is small and shaped as if it were molded between a pair of parentheses. It’s most readily identified by two stubby legs that protrude from its rear.
The moth is also small and slender with a grayish-brown body and an upturned “tail”. When its not in flight, the wings are folded. Where the wings of the male moth meet, you’ll see three yellow diamond shapes.
The eggs are shaped like small yellow footballs. They will be on the underside of the leaves and might be laid individually or in small clusters.
You might find the caterpillars feeding anywhere on the plant, but when the cabbage is young, they prefer the bud.
The imported cabbageworm is a darker green with faint yellow stripes down its body, and it’s covered with fine hairs that give it a velvety look. The parent is the imported cabbage white moth.
This moth measures 1-3/4 inches long with black spots on the upper wing and a yellow tint to the underside of the wings.
The ridged, bullet-shaped eggs are laid individually and might be found anywhere on your cabbage. They are white when they are first laid but turn dark yellow.
You’ll find the caterpillars on the undersides of the leaves next to the veins or the central rib. They feed near the center of the plant, but do not necessarily feed only near the veins.
The Wormy Wrigglers: Cross-Striped Cabbageworms, Beet Armyworms, and Cutworms
These worms also are the larva of various moths, but they prefer not to be lumped together by their color or markings.
Cross-striped cabbageworms measure about 3/4 inch long. They are bluish-gray with black and yellow stripes along the length of the sides of their bodies and black stripes across the width of their backs.
The moth has a 1-inch wingspan and is brown to yellowish brown with darker zigzagged markings on the wings.
The yellowish eggs are laid in masses of 20 or 30 creating a scale-like look on the underside of the leaves.
Cross-striped cabbageworms feed on any tender part of the plant, but they prefer the buds.
Beet armyworms are dark green to black with fine, wavy white lines down the length of the back and a wider stripe along the length of the sides. They have dark heads, and they also usually have a dark spot on each side just above the second pair of legs.
Beet armyworms are the larva of the small mottled willow moth, a gray or brown moth with mottled brown upper wings and white lower wings with dark brown veins and a border with a thin stripe of dark brown and an outer band of white.
The eggs are laid in clusters of up to 80 eggs. You will find the eggs under a covering of cottony white scales.
After they first hatch, you will find the larva feeding together near their egg cluster. As they grow, though, they move away from the cluster, and each larva may feed on several neighboring plants.
Several varieties of cutworms do get lumped together. They are gray with smooth skins that give them a slippery, greasy look, so they are sometimes mistaken for grubs, as is the damage they do to foliage.
They are the larva of several brown or gray, nocturnal, dark-winged moths.
The moths lay their eggs at night on weeds, grass, your cabbage, and other host plants.
Like the moths, cutworms are nocturnal and feed at night on the stems and, sometimes, the foliage of young plants. During the day, they retreat into tunnels underground where they feed on roots and can cut through the stalk, killing the plant.
The Buggy Gang: Flea Beetles, Cabbage Aphids, and Cabbage Maggots
Flea beetles are small, shiny, striped or solid color beetles of various species that can be brown, bronze, black, or metallic to bluish gray. One thing they all have in common is the large back legs that enable to leap around your plants.
Flea beetles lay their eggs on the ground, and the 1/4 inch long larva feed on the roots of the plants.
The adult flea beetles do more damage than the larva, though. As they feed on the leaves, they create “shotholes” that give leaves a lacy look. When the damage is severe enough, it can stunt or kill young plants. Flea beetles also can spread wilt and blight among your plants.
Like other aphids, cabbage aphids have long antenna and pear shaped bodies. Cabbage aphids are light green with a waxy, grayish coating.
You’ll find cabbage aphids on the undersides of leaves where they suck the sap from your cabbage. The leaves may wrinkle, curl, or cup, and cabbage heads may be stunted.
Cabbage maggots are legless, white larva with pointed heads and blunt rears. They burrow into and feed on the stems and roots of your cabbage. They can riddle plants with tunnels that allow other pests and diseases to gain entrance. Your cabbage may look purplish or gray-blue rather than green and be stunted or wilted.
The eggs are laid by dark gray flies that have three stripes on their backs, black legs, and smoky gray wings.
To reduce the risk of maggot infestations, avoid planting your cabbage early if there is likely to be an extended period of cool, wet weather.
Controlling Cabbage Pests
One way to control all of these pests is to grow your cabbage inside of row covers. These covers prevent adult insects from laying their eggs on your cabbage or on the ground around it.
Flea beetles and some moths overwinter in brushy areas. If you have such an area near your garden, mowing it down removes this winter survival haven.
Tilling your garden in the fall exposes eggs and pupae in the soil to winter’s cold, killing them.
Although it’s time consuming, if you find eggs, caterpillars, or maggots on your cabbage, you can remove them by hand. If you find one heavily infested leaf or plant, sacrifice it and remove it to protect the rest.
Cabbage does grow low to the ground, but aphids have very weak legs. If you flick them off of your cabbage with a blast of water from your garden hose, they may not be able to climb back up onto your plants.
If you spread diatomaceous earth around the base of your cabbages, it will puncture soft-bodied caterpillars, cutworms, and aphids that crawl over it.
Bacillus thuringiensis eliminates cutworms, but it can also harm beneficial insects, as can garlic oil spray.
If you plan to use garlic oil spray, you should test the concentration on one plant and dilute it as needed before spraying it on all of your plants to get rid of aphids. You should also test homemade sprays made with alcohol and dishwashing liquid before using them extensively.
Tomato leaf spray is friendly to plants, but tomatoes are related to nightshade, so those who are allergic to nightshade should wear gloves when chopping the tomato leaves to make this spray for controlling aphids on cabbage, kale, and other related plants.
Attracting or releasing insects that prey on these cabbage pests in another way of controlling them. For example, ladybugs or lady beetles, lacewings, and hoverflies prey on aphids while fireflies prey on cutworms.
You can purchase lady beetles, lacewings, and hoverflies to release in your garden, and fireflies are attracted to areas where there are short trees and shrubs in at they use as resting places during the day.
Companion plants can also help repel pests or life them away. Radishes and nasturtiums lead flea beetles away from cabbage while catnip and basil repel them. Imported cabbage white moths are attracted to mustard but repelled by thyme while bittercress, which is related to mustard, attracts the diamondback moth but kills diamondback caterpillars when they begin to feed on it.
How to Use Intercropping Wisely to Increase Your Harvest
Tasha has been an active herb gardener, foodie, and from-scratch cook since the year 2000. In 2014, she started homesteading for greater self-sufficiency in rural Surry County, North Carolina. She currently keeps dairy goats, chickens, ducks, a pet turkey, worms, and (occasionally) pigs. She gardens on about two acres and grows a large variety of annual and perennial edible, medicinal, and ecosystem support plants. She is an Extension Master Gardener Volunteer and teaches classes in her community related to Edible Landscaping, Organic Gardening, and Introduction to Permaculture. She has also co-authored several books about backyard chickens, livestock watering systems, and vinegar production.
The concept of intercropping seemed completely revolutionary. Not only did you get to grow more food in a small garden, but you could reduce weeds, minimize pest pressure, water less, better control soil fertility, and more.
Well, I couldn’t wait to put those ideas to practice in my own garden. So, I set about intercropping in all my garden beds. It took forever to plant and my garden was a complete disaster. I had fungal problems, pest issues, piddly crop production, and my soil was barren by the end of the experiment.
Frustrated, heart-broken, and hungry for answers and vegetables, I went back to the text to find out what I’d done wrong. That’s when I read these words, “Just as with companion planting over time, you should proceed with care.”
Intercropping Must be Implemented with Care
I tell the story earlier as a cautionary tale. I still think intercropping is revolutionary and can transform your garden over time, but there is no magic formula. You’ll need to do some careful experimentation to find out what works in your garden.
With that in mind, let’s dig into the details on intercropping and how it might actually benefit your garden.
Examples of Intercropping
You probably already have some idea of what intercropping is, but looking at a few examples is the best way to understand the concept.
You may have heard of this planting method – corn, squash, and beans – as the ultimate interplanting combo or plant guild.
For the three sisters, you plant corn a few weeks before you put in beans and squash to let it get established. Then, you use the corn as a trellis for pole beans. The corn is a heavy feeder, so it will take all the nutrients from the soil. However, beans – with the help of nitrogen-fixing bacteria – will supply their own nitrogen so they don’t need to compete for nutrients.
Squash vines are grown below the corn and beans as a kind of living mulch. That keeps down weed pressure. Plus, by shading the ground, it helps keeps the soil moist.
Carrots and Radish
Perhaps you’ve heard about planting carrots and radish together. Carrots take a long time to germinate and radish can be harvested in 21-35 days. That makes them the perfect pairing.
The radishes keep down the weeds until the carrot tops are large enough to see and weed around. Then, you harvest the radish and the carrots keep on growing.
Throughout the article, you’ll find some more examples and how they work together. So, read on.
How Intercropping Works
Interplanting or intercropping basically involves using 2-3 crops in the same planting area, at roughly the same time, for some beneficial purpose. The goal is to get the interplanted crops to support each other’s growing habits, so you get a better result in the garden.
Here are a few broad concepts to demonstrate some of the ways that plants can benefit each other.
1. Sun and Shade
Where I live, we have long, hot Summers that make planting cool-season crops for fall very difficult. Our erratic spring also makes it hard to grow cool-season crops to maturity before hot weather gets the best of them.
With intercropping though, I can start cool-season plants in the shade of warm-season plants in summer. Then, when temperatures cool down, the warm season crops come out and my cool-season plants get full sun. Or I can start fast-growing tall warm crops in front of late-maturing cool-season crops in spring.
I plant sunflowers in front of spring cabbage. I plant my cabbage on the Northside of my still-drying dent corn in fall.
I start winter spinach and collards in the shade of my trellised Malabar spinach. Turnips go in on the shady side behind pole beans.
2. Root Depth
There are two primary root structures you see in a vegetable garden – fibrous and taprooted. Fibrous root systems for annual vegetables tend to spread in the top few inches of soil. Taproots go down 8-10 inches or more.
Taproots get stunted if there are too many nutrients in the top few inches of soil. If you plant taproots next to fibrous-rooted plants, those fibrous roots will take the nutrients in the upper inches. That will help drive taproots deeper.
Alternating rows of lettuce with rows of carrots is a good example of this kind of interplanting at work. It also makes for a pretty display if you use red-colored lettuces.
3. Leaf Structure
Similar to interplanting based on root structure, leaf structure can impact interplanting decisions. By mixing and matching upright with low growing plants, or bushy with spindly plants, you can plant closer together and still get good airflow. For example, cabbage with its bushy growth habit pairs well with more spindly, upright onions.
Onions go in first, in late winter and get a little time to establish. Then, the cabbage gets transplanted in early spring just about when weeds might try to take over your onion bed. From my own experimentation, this seems to work best if you choose faster-maturing cabbage that can be harvested before the onions start to bulb.
4. Growth Speed
Using fast-maturing plants with slow-growing plants is another good interplanting option. Those carrots and radish mentioned earlier are classic examples. But I also like to grow baby crops with full size crops for the same effect.
The baby crops get densely planted to crowd out weeds. Some get harvested for greens, others for baby bulbs. The key is that you must harvest your baby crops by the time your full-size or slower-growing crops begin to need that soil space for their root systems.
5. Feeding Habits
Some plants are heavy feeders that require a lot of nutrients. Others are gleaners that will take whatever is left in the soil and make the most of it. Legumes, inoculated with rhizobia, are able to fix their own nitrogen and can glean the other micro and macro-nutrients they need.
You would never want to interplant a heavy feeder with another heavy feeder. But, putting gleaners or nitrogen fixers with heavy feeders tends to work well. Mixing legumes with grains is a perfect example of this kind of interplanting.
6. Companion Planting
Companion planting is another form of intercropping. For example, planting basil and tomatoes in your asparagus patch to deter asparagus beetles also gets you more yields from your asparagus patch.
Growing coriander with your cabbage can be a deterrent for cabbage pests on young plants. Plus, it also gets you a fast crop of coriander greens while your slower-growing cabbage gets going.
7. Mix and Match
The best interplanting strategies tend to fulfill multiple roles. The crops may be beneficial companions in terms of pest control while also maximizing root growth and leaf structure aspects as well as feeding habits.
The Problems with Intercropping
Now, back to that warning at the start of this post.
As good as all that sounds, intercropping won’t work in every situation. Also, the things that work for someone else might not work for you.
The three sisters’ interplanting system is an absolute disaster in my garden. When I plant those three things together, I end up having massive pest and fungal problems due to my climate and the invasive pests in my area. Whereas, when I plant them separately, I can easily manage pest and fungal issues with no problem.
To help you figure out what might work for you, here are some things to consider when making decisions about which type of intercropping would suit you:
If you live in a humid area, your plants need good airflow to limit fungal issues. Some intercropping will trap moist air around your plants. That will increase the likelihood of your plants developing fungal problems and being less productive.
2. Pest Problems
If you are an organic gardener, you need to be able to handpick pests from your plants at times. So, you’ll want to make sure that your intercropping doesn’t make it hard for you to do that.
Also, your intercropping shouldn’t create safe havens for insects. For example, low growing lettuce might not get in the way of more upright growing cabbage. But slugs can easily hide under lettuce during the day and then eat your cabbage leaves at night.
3. Soil Fertility
Intercropping does not work well in soil that is not fertile. If you have a brand-new garden with very little organic matter and few nutrients, then your plants need extra soil space to access sufficient nutrients.
As you begin to improve your soil with annual applications of complex compost and mulch and the use of cover crops, then interplanting becomes more effective.
4. Plant Spacing
When you interplant in fertile soil, you can group plants more closely together. Those closer groupings get you the benefits I mentioned at the outset like watering less, fighting fewer weeds, and getting more food from a small space. However, many gardeners take this too far.
Realistically, intercropping might allow you to plant 10-20% more plants in the same space. Many gardeners, though, try to double yields with this method.
I can tell you from experience that you can get away with it for a few years. Eventually, though, you’ll run up against the reality of a nutrient-depleted garden.
How to Interplant Well
With all that background, here are some tips to help you start using this revolutionary tool in your garden with the wisdom I wish I’d had at the outset.
1. Go Slow
First off, take John Jeavons’ advice (and mine) and proceed with care. Don’t revise your entire crop rotation to interplanting all at once. Try a couple of interplantings a season and see how they go.
2. Choose the Right Varieties
Second, varieties matter. A giant ball head cabbage is a whole different thing than a small 65-day cabbage, like Earl Jersey Wakefield or Golden Acre.
Bunching onions are used differently in intercropping than bulbing onions. Romaine, leaf, and head lettuce are each unique in terms of leaf structure. Beans can be runners, half-runners, or bushing in style. Squash can be vining or non-vining. Tomatoes are determinate (bush) or indeterminate (vining).
Make sure you choose specific plant varieties with the growth habits, size, and nutrient needs for your interplanting goals.
3. Make Adjustments
If you interplant and see that it’s not working, pull your faster-growing crop ASAP and start them somewhere else instead. Or, add fertilizer to get plants back on track.
Interplanted crops should not grow slower or produce less than your individually planted crops. If they seem to be doing poorly or not producing, then treat them just like you would individually planted crops. Yank ‘em or fix ‘em so you don’t end up with pest or pathogen issues invited in by sickly plants.
Intercropping is an awesome gardening tool that requires a bit of skill to use effectively. If you are new to gardening, save interplanting for your second or third year of gardening. But, if you already have some experience growing plants individually, then take your time building your interplanting skills.
Brassica Pests & Diseases
• A List of Common Pests & Diseases
• Basics of Prevention & Control
• Further Resources
Other methods can also be employed, but the above four are fundamental to management of the most common problems listed below.
- Flea beetles
- Crucifer flea beetle ( Phyllotreta cruciferae )
- Striped flea beetle ( Phyllotreta striolata )
- Cabbage «worms»
- Cabbage looper moth ( Trichoplusia ni )
- Imported cabbageworm ( Pieris rapae ); aka small white butterfly
- Diamondback moth ( Plutella xylostella ); aka DBM or cabbage moth
- Aphids (several species target members of the brassica family)
Crop rotation. For growers/gardeners who practice proper (at least three-year) crop rotations, insect pests of brassicas are less problematic.
Transplants. Seedlings of direct-seeded crops are more vulnerable to damage — get a head start against flea beetles and other pests by using transplants.
Weed control. To reduce potential feeding sites in the spring, control weeds, especially those in the brassica family, and distance any garden flowers you are growing that are in the same family.
Row covers. Installing floating row covers is time well spent for protection against all of these insect pests. Row covers must be placed and the edges immediately sealed with soil once the seed or transplants are in the ground, and repositioned carefully if removed for weeding. If you choose not to invest in row covers, we recommend becoming familiar with alternative prevention and control measures.
Several bacterial and fungal diseases are worth knowing about. You can gain a better understanding of the nature and root causes of common brassica diseases by referring to information provided by agricultural universities and extension agencies, as listed below.
- Black rot of crucifers ( Xanthomonas campestris pv. campestris )
This is most often the result of infected seeds or transplants. Black rot can be identified by V-shaped yellow lesions on the leaves. In Brussels sprouts tiny, immature sprouts often blacken and die on the stalk. This bacterial disease can destroy the crop and then persist in the soil for many years, so prevention is the best medicine.
Black rot can be avoided through crop rotation and using only seed lots that have tested negative for black rot. At Johnny’s, we test all of our seed lots of broccoli, cabbage, cauliflower, collards, Brussels sprouts, Flower Sprouts , kale, Kalettes, and kohlrabi before selling them.
- Club root of crucifers ( Plasmodiophora brassicae )
This disease causes the roots to become swollen and distorted, and limits water uptake. In addition to the root malformation, the leaves yellow and wilt. Its presence often goes undetected as the effect on the aboveground portion of the plant may not become apparent until water stress occurs.
Like black rot, club root can persist in the soil for many years. This disease is best prevented through proper crop rotation.
How can all these diseases be avoided? Be sure to observe these fundamentals:
Practice proper rotation. If possible, only grow brassicas on the same ground every third or fourth year. These problems are mostly an issue in areas where crops have not been properly rotated. For specifics, contact your local cooperative extension agent.
Plant high-quality seed. Johnny’s sells only seed lots that have tested negative for black rot.
If you have problems. Let us know, or see your crop advisor/cooperative extension agent.
Of course, there are many other measures that can be employed, with an integrative approach, to minimize pest and disease pressure while optimizing the overall health of your soils and crops. But with proper crop rotation, soil preparation, farm hygiene, and high-quality seed, most brassica pests and diseases can be avoided.