Kale is a popular, nutrient-dense addition to many home gardens, prized for its robust growth and cool-weather tolerance. As a member of the Brassica family, it is a favorite target for a wide range of garden pests. These insects often leave behind a trail of destruction. Understanding how to interpret the damage is the first step in protecting your harvest. This guide will help you identify the specific signs of damage and provide targeted solutions to restore your kale plants to health.
Reading the Signs: Damage Identification
The visual evidence left on the leaves provides a clear indication of the type of pest feeding on your kale. Large, irregular holes, often found closer to the center or edges of the leaves, signal extensive chewing damage. This is usually caused by larger pests, such as caterpillars, which consume significant portions of the foliage. Plants suffering from this attack may also show small, dark green fecal droppings, known as frass.
Numerous tiny pinholes scattered across the leaf surface, sometimes called a “shotgun” pattern, suggest a very small insect is feeding. This damage occurs when the culprit scrapes and chews the superficial layer of the leaf. While older, established plants can often tolerate this damage, young seedlings may be severely stunted by a heavy infestation.
Sap-sucking pests cause plant distortion rather than missing leaf tissue. These pests pierce the plant cells and withdraw inner fluids, leading to symptoms like yellowing, curling, or puckering of the leaves. Severe infestations can stunt the plant’s growth, and a sticky residue called honeydew may accumulate. Silvery or clear, slimy trails across the lower leaves or surrounding soil indicate the presence of mollusks like slugs or snails.
The Most Common Kale Pests
The most frequent offenders fall into three main categories. The first is the Cabbage Worm, which includes the larvae of the imported cabbageworm and the cabbage looper. The imported cabbageworm is a velvety green caterpillar that blends seamlessly with the leaves. The cabbage looper is a pale green caterpillar that moves with a distinctive looping motion. Both larvae are highly destructive, chewing large, irregular holes.
Another common pest is the Flea Beetle, a tiny insect measuring about 1/16 of an inch long. These beetles are typically dark brown or black and possess large rear legs that allow them to jump when disturbed. They emerge in the early spring and are responsible for the small, round pinholes, especially in young plants. The adults lay eggs in the soil, and the resulting larvae feed on the plant roots, which weakens the kale.
The third common pest is the Aphid, which appears in dense clusters on the undersides of leaves and on new growing tips. Cabbage aphids, which specifically target brassicas, are often gray-green and covered in a waxy, white coating. These insects reproduce rapidly, and their colonies cause the leaves to curl, distort, and potentially stop growing as they extract plant sap.
Effective Strategies for Pest Control
Protecting kale involves a layered approach starting with physical exclusion. Floating row covers, which are lightweight fabrics, act as an effective physical barrier by preventing adult moths and beetles from landing to lay eggs. These covers allow sunlight and water to pass through and should be set up immediately after planting to protect vulnerable seedlings. For larger pests, simple manual removal is a direct and effective tactic.
Regularly inspecting the undersides of leaves allows for the handpicking of cabbage worms and the removal of aphid-infested leaves. Aphids can also be dislodged using a strong jet of water from a hose, which often eliminates small colonies. For infestations requiring more intervention, several organic treatments are available to target specific pests.
Several organic treatments are available to target specific pests. Bacillus thuringiensis (Bt) is a naturally occurring soil bacterium highly effective against chewing caterpillars like cabbage worms; when ingested, Bt disrupts the pest’s digestive system. Insecticidal soaps are useful against soft-bodied pests such as aphids, as the solution suffocates the insects upon contact. Neem oil, derived from the seeds of the neem tree, works as both a repellent and an insecticide, disrupting the life cycle of many pests.
Cultural practices are an important component of long-term pest management. Rotating the location of your kale and other Brassica family plants each season prevents pest populations from building up in the soil. Maintaining good garden hygiene by removing crop debris eliminates overwintering sites for pests. Incorporating companion plants like thyme or borage can help confuse or deter pests, as their strong scents mask the attractive smell of the kale.