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The brassica family includes a variety of delicious vegetables. Brassicas such as kale, cabbage, and broccoli are perfect when eaten fresh in salads or as tasty side dishes in cooked meals.

Brassicas are relatively trouble-free, easy to grow crops. However, they do face some challenges, especially from pests. Many insects target brassicas; some eat through the heads of cabbages, while others can quickly damage the roots and leaves of young kale.

Here are 12 common issues to watch out for when growing brassicas.


aphids on cabbage
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Small, sap-sucking insects that cause curled and yellowed leaves on brassica plants. Control them with insecticidal soap or by introducing beneficial insects like ladybugs.

Cabbage Worms

cabbage worms
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Cabbage worms are green caterpillars that chew large holes in the leaves of cabbages and other brassicas. Handpick them or use Bacillus thuringiensis (Bt) to control infestations.

Flea Beetles

flea beetles
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These tiny, black beetles that create a small, round holes in the leaves. Use row covers or neem oil to protect young plants.

Black Rot

cabbage black rot
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A bacterial infection that causes V-shaped lesions on leaves and blackened veins. Infected plants must be removed and destroyed.


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As winter transitions into spring, birds become the main threat to your brassicas. With fewer food sources, hungry birds especially pigeons turn to our gardens for sustenance. They can quickly eat away at brassicas, tearing the leaves and leaving them ragged and bare.

Potassium Deficiency

browning of edge of cabbage
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Inadequate levels of potassium can result in weak stems and browning of leaf edges. this can be be corrected with a potassium-rich fertilizer.

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white fly whiteflies whitefly
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Whiteflies significantly impact brassicas by feeding on plant sap, which diminishes the plants’ vigor and causes leaves to yellow and wither.

Additionally, whiteflies excrete a sticky substance known as honeydew as they feed. This honeydew coats the leaves, promoting the growth of sooty mold that blocks sunlight and impairs photosynthesis, further stunting plant growth.

Harlequin Bugs

harlequin cabbage bug
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Harlequin Bugs emerge in the summer when the weather warms up, targeting brassica plants like kale. These pests are easily identifiable due to their colorful appearance.


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If the brassicas leaves start showing a brownish-bronze color and a blistered appearance, this is likely caused by thrips. These insects puncture the plant’s leaf tissue and extract the sap, especially in plants like cabbage. Cover plants with mesh row covers to prevent them from harming your plants.


A healthy fresh curly kale.
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Clubroot is a fungal disease that affects the brassica family. It leads to malformed and swollen roots. When young plants are infected, they become stunted and eventually die, while older plants fail to develop heads or reasonable growth.

Fusarium Wilt

kale with yellow leaves
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Fusarium wilt is a fungal disease that causes the plant’s leaves to turn yellow. The discoloration starts with the lower leaves and gradually moves upward, potentially killing the plant. Plants can recover if temperatures drops below 75 degrees after the plants have been infected.

Nitrogen Deficiency

cabbage with yellow leaves
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Low nitrogen levels cause slow growth and yellowing of older leaves. Correct with a nitrogen-rich fertilizer.

10 Natural Ways to Add Nitrogen to Your Garden Soil

How to Grow Kale

kale in garden bed

Here’s everything you need to know about growing kale successfully, from seed selection to harvesting.

How to Grow Kale from Tiny Seeds to Leafy Greens

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squirrel with tomato
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To help you safeguard your garden, we’ve handpicked 17 plants Squirrels tend to avoid due to their taste, smell, or texture.

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Bright summer vegetable garden and flower bed.
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While pre-made raised beds can be expensive, building your own is a cost-effective alternative. With some basic materials and a bit of effort, you can construct your own raised beds at a fraction of the cost. Here are 16 DIY Raised garden bed projects to help you get started.

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