Diseases & pests

Small Winter Moth

Operophtera brumata

You will notice the Small Winter Moth in spring by its green caterpillars that, when crawling, have a cat's hump appearance. They bore into buds, flowers, and young leaves from the shoot and leave holes. The females are wingless and walk up the trunks in mild late autumn to lay their eggs on the buds. When they multiply in large numbers, only the leaf veins remain on young shoots.

Spanish slug

Arion vulgaris

The Spanish slug is the most feared omnivore in the vegetable bed. It feeds at night and in damp weather, eating irregular holes into leaves, and often clears young lettuces or seedlings completely. The silvery shiny slime trails the next morning give it away. Soft, freshly planted batches are especially at risk.

Spotted Wing Drosophila

Drosophila suzukii

The Spotted Wing Drosophila (Drosophila suzukii) is a small fruit fly that, unlike native species, pierces healthy, still ripening fruits with its serrated ovipositor to lay eggs. The hatching larvae continue to feed inside, causing the fruit to quickly become soft, sunken, and begin to ferment. Thin-skinned berries and stone fruits are primarily affected; an infestation often only becomes apparent shortly before harvest through mushy spots and small larvae visible in the flesh.

Thrips (thunderflies)

Thysanoptera

Thrips are tiny, elongated insects that become particularly active on warm, muggy days, which is why they are also called thunderflies. They suck on leaves, shoots and flowers and leave behind silvery shiny patches as well as fine black specks of excrement on the underside of the leaf. Flowers often become deformed and get unsightly feeding damage along the edges, and young shoots can look stunted in growth. If you look closely, or with a magnifying glass, you can make out the slender, yellowish to dark insects between the petals.

Tomato leafminer

Tuta absoluta

The tomato leafminer (Tuta absoluta) is a small moth whose caterpillars feed inside the leaves and fruit of tomatoes and their relatives. Typical are pale, winding mines in the leaves, which turn brown and dry up; where the fruit is attacked, the caterpillars bore straight into the flesh. You can spot an infestation best by holding leaves up against the light: the tunnels and the small dark crumbs of frass inside them are then clearly visible. Left untreated, the pest can spread quickly across the whole plant and to neighbouring plants.

Two-spotted spider mite

Tetranychus urticae

The two-spotted spider mite appears above all in dry heat in the greenhouse and sucks on the underside of the leaves, which makes the leaves first pale and speckled, then dull bronze coloured, before they dry up. With a heavy infestation, fine webbing covers the shoot tips. The animals, only 0.5 mm across, multiply at breakneck speed in the heat, so that a few mites can turn into a plague within two weeks.

Vine Weevil

Otiorhynchus sulcatus

The vine weevil is the larva of the nocturnal beetle Otiorhynchus sulcatus and causes the actual damage. While the beetle leaves typical, notch-shaped feeding marks on the leaf edges above ground, the creamy white, C-shaped larva feeds on roots and the root collar underground. Affected plants such as Rhododendron, strawberry, or Hosta often wilt surprisingly, even though the soil is moist, because the water supply no longer works through the damaged roots. In cases of heavy infestation, you can almost lift the plant out of the pot without any roots.

Water vole

Arvicola terrestris

The water vole, commonly called a burrowing vole, lives underground and feeds on roots, tubers and the bark at the root collar. Typical are flat, arched mounds of soil in rows as well as tunnels close beneath the surface. Affected plants wilt abruptly or can be pulled up without effort, because the roots have already been gnawed away. On young fruit trees an attack at the root collar can lead to the tree dying within a short time.

Whitefly

Trialeurodes vaporariorum

The whitefly is a heat loving sap sucker that appears above all in the greenhouse and on container plants: larvae and pupae sit on the undersides of the leaves, and when the plant is knocked the white adults fly up in a cloud. Their sticky honeydew coats leaves and fruits and is colonised by black sooty mould; badly infested plants turn yellow and struggle. They can also transmit viruses.

Wireworm

Agriotes spp.

Wireworms are the yellow-brown, hard larvae of click beetles and live several years in the soil. They bore narrow tunnels in potato tubers and carrots, making the harvest unsellable and often leading to rot through the wounds. The infestation is especially strong in areas that were previously meadow or heavily grassed.