The globe artichoke (Cynara cardunculus var. scolymus) is a large, thistle-like perennial plant cultivated for its edible, immature flower buds. Producing the large, fleshy hearts and bracts requires significant energy, making the plant a target for numerous pests throughout its growing cycle. Managing insects, mollusks, and other threats requires timely intervention to protect the plant’s health and yield.
Recognizing Signs of Infestation
Identifying a pest problem early often relies on recognizing damage symptoms rather than spotting the pest itself. Chewing insects typically leave ragged edges and distinct holes in the large leaves, which reduces the plant’s ability to photosynthesize. Severe feeding damage can result in leaves that appear lacy or skeletonized, often caused by nocturnal feeders like slugs or certain caterpillars.
Sucking insects, such as aphids, extract plant sap, causing curled, distorted, or yellowing foliage. These pests also excrete honeydew, a sticky, sugary substance that fosters the growth of sooty mold, appearing as a dark film on the leaves and buds. More damaging signs involve bore holes in the stems or flower buds, often accompanied by fine, sawdust-like excrement called frass. Frass or black, wilting stems can indicate internal larval activity, such as that of the artichoke plume moth.
Key Insect Pests and Management Strategies
The Artichoke Plume Moth (Platyptilia carduidactyla) is a damaging pest whose larvae tunnel into the stalks and buds. Management requires targeting the larval stage before they bore deeply into the plant tissue. Applying a microbial insecticide containing Bacillus thuringiensis (Bt) is effective, especially when the larvae are small and active on the exterior. Monitoring adult moth populations with pheromone traps helps predict egg-laying periods, allowing for precise timing of control measures.
Aphids are common sap-sucking pests that cluster on new growth and the undersides of leaves. For light infestations, use a strong jet of water to dislodge them. For heavier populations, apply treatments like insecticidal soap or neem oil, which work by smothering the insects. These topical treatments must be applied thoroughly to contact the pests directly, especially on the sheltered undersides of the leaves.
Armyworms and cutworms, the larval stage of various moths, are voracious chewers that can quickly defoliate plants, with armyworms often feeding in groups. Small numbers of these caterpillars can be removed by hand and destroyed. Similar to the plume moth, they can be controlled with the targeted application of Bacillus thuringiensis (Bt), which disrupts the digestive system of caterpillars after ingestion. Cultural practices, such as disking or tilling the soil after harvest, also help to kill pupae and remove the food source.
Slugs, Snails, and Other Non-Insect Threats
Slugs and snails are mollusks that damage artichokes, leaving behind their characteristic silvery slime trails. These pests are nocturnal and seek refuge during the day in cool, damp places, such as under plant debris or dense weeds. Handpicking is best conducted at night or early morning when the mollusks are most active.
Physical barriers can deter these pests from reaching the plant’s heart and buds. Copper flashing or copper tape creates a mild electrical charge when the mollusk crosses it, serving as a repellent barrier. Another approach involves sinking shallow containers of beer or a yeast-sugar mixture into the soil, acting as a pitfall trap that attracts and drowns the pests. For widespread issues, iron phosphate baits are a less toxic alternative to traditional metaldehyde baits, as they are safe for pets and wildlife when used as directed.
Proactive Garden Management
Preventative measures focused on the growing environment are key to managing infestations. Proper plant spacing, typically three to four feet apart, is necessary to ensure good air circulation, which reduces the moist conditions favored by many pests and fungal diseases. Weeds should be managed consistently, as they can serve as alternative host plants or provide shelter for pests like armyworms and slugs. Sanitation involves removing old plant debris and cutting back dead or damaged leaves throughout the season to eliminate overwintering sites for pests like the plume moth.
Incorporating compost and organic matter into the soil contributes to overall plant vigor, enabling the artichoke to better withstand minor pest damage. Encouraging beneficial insects, such as lady beetles and lacewings, by planting diverse flowering species nearby provides pest control, as these predators feed on pests like aphids.