Why Is My Artichoke Plant Covered in Aphids?

Artichoke plants are attacked by several aphid species, with black bean aphid (Aphis fabae) and artichoke aphid (Capitophorus elaeagni) being the most commonly encountered in UK gardens. Colonies form on the undersides of leaves, on shoot tips, and — most problematically — between the scales of developing artichoke heads, where they are very difficult to remove and can render the heads unappetising even if technically edible. Understanding the specific risk of aphids inside heads is important for managing artichokes as a food crop.

Aphids on leaves and shoot tips

Colonies on the undersides of leaves and at shoot tips can be managed effectively with physical methods. A firm jet of water from a hose knocks colonies off leaves quickly — repeat every few days while infestations are present. For persistent colonies, insecticidal soap spray applied to the undersides of leaves and to shoot tips gives good control without lasting residues. Avoid spraying any product directly onto developing heads if harvest is approaching.

Aphids inside the heads

Once aphids have moved into the scales of a forming head, contact sprays cannot reach them. The best approach is prevention — checking developing heads weekly and removing any aphids that are beginning to colonise the outer scales before they move deeper. Soaking harvested heads upside down in salted water (1 tablespoon salt per litre, 30 minutes) before cooking reliably floats out any aphids, slugs or other small insects from between the scales.

Encouraging natural predators

Ladybirds, hoverfly larvae, lacewing larvae and parasitic wasps all prey on aphids and are highly effective at controlling populations if not destroyed by broad-spectrum insecticides. Grow nectar-rich plants nearby to support adult hoverflies and parasitic wasps. Avoid applying any broad-spectrum pesticide that kills predators as well as aphids — this typically makes aphid problems worse in subsequent weeks.

Ants and aphids

Ants farm aphid colonies for their honeydew secretions, protecting them from predators. If ants are numerous on your artichoke plants, apply a sticky barrier around the base of each stem to prevent ants climbing up — this allows natural predators to operate without the ants' interference.