Tip #223: Common Kale Pests

Kale is one of the most popular plants that our customers like to grow. Some of our favourite varieties include Dinosaur, Redbor (tall, purple frilly kale), and Darkibor (green frilly kale).

While generally easy to grow and adaptable to a variety of conditions, there are a few pests that can affect the growth of this plant we’ve encountered over the past several years.

1. Caterpillars
Green caterpillars, most commonly cabbage loopers that turn into moths, can blend in almost perfectly with the colour of the leaves. They are Commonly found near the main ribs of the leaf, sometimes hiding on the stems or underside of the leaves. Often you need to look very closely to see them. If left untreated, they can destroy the entire plant. Common symptoms include leaves looking skeletonized and black frass near the stem of the plant and on the soil

Can you spot the caterpillars in this photo? Photo by Mike Linksvayer

2. Aphids
Aphids are small sap-sucking insects that can lead to stunted growth on your kale plants. Sometimes called “plant lice” due to their ability to multiply quickly and take over a plant, they can be a real nuisance to the home gardener if not treated quickly. Aphids typically appear as greyish insects on on the undersides of leaves, as well as in the central crown where new leaves and new growth is taking place.

Treatment and Prevention
For both aphids and cabbage looper caterpillars, prevention and early identification are the best remedies. This includes choosing healthy transplants for your garden, providing them with good growing conditions, and regular checks for these insects. In addition, kale (and most other plants in the brassica family) can be planted under row covers to prevent these insects from attacking your plants in the first place.

If these insects are discovered, there are several ways in which you can remedy the situation. First, a sharp stream of water to dislodge the insects from the plants can work as a daily or weekly task. For caterpillars, we recommend hand picking the caterpillars off the plants (put them in a bucket of soapy water to drown). For aphids and caterpillars, an insecticidal soap solution also works well, as long as you can spray directly onto the insects. Repeat as needed until plants are free from these insects.