What pests attack cucumber?

Cucumber beetles, Broad mite, Leaf Miner, Squash bug, Two-spotted spider mite, Whitefly

What diseases affect cucumber?

Bacterial soft rot, Bacterial wilt of cucurbits, Downy Mildew, Fusarium wilt, Grey mould, Leaf Curl Virus, White mould (Sclerotinia), Anthracnose, Verticillium wilt

Cucumber pests and diseases: how to recognise them

Q: Which cucumber problems need quick action?

Cucumber beetles: Yellow beetles about 6–7 mm long with three black stripes (striped cucumber beetle) or yellow-green with 12 black spots (spotted cucumber beetle) on seedlings, leaves, flowers and fruit. Bacterial soft rot: Slimy ooze and a strong, foul smell from the rotting tissue. Bacterial wilt of cucurbits: Leaves on one runner turn dull green and wilt, even in moist soil; the wilt spreads along the vine to the crown and the whole plant dies. Downy Mildew: Pale green, yellow, purple or brown blotches on the upper side of leaves, often angular where they are bordered by the veins. Fusarium wilt: At first the plant seems to recover overnight, but the wilt soon becomes permanent; growth is stunted and few fruits form. Grey mould: Small, almost translucent spots that turn brown and water-soaked; affected tissue goes soft, dark and dies, and buds and flowers shrivel. Leaf Curl Virus: Young leaves are small, curl upward and look crumpled, with yellowing between the veins and along the margins. White mould (Sclerotinia): Masses of fluffy white, cotton-like mould on the affected parts, especially in cool, damp weather.

Cucumis sativus

The pests, diseases and disorders recorded for cucumber in our library, each with a photo and its first symptom. Every page has the full list of symptoms, organic and chemical treatment and prevention.

At a glance

Problems in total	16
Pests	6
Diseases	9
Growing conditions	1
Need quick action	8

How to grow cucumber · All pests and diseases

Pests

Cucumber beetlesYellow beetles about 6–7 mm long with three black stripes (striped cucumber beetle) or yellow-green with 12 black spots (spotted cucumber beetle) on seedlings, leaves, flowers and fruit.Also called: striped cucumber beetle, spotted cucumber beetlePhoto: Pollinator, CC BY 2.5, Wikimedia Commons
Broad miteLeaf edges pucker and turn downward because the leaves cannot expand normally.Photo: David Riley, University of Georgia, Bugwood.org, CC BY 3.0, Wikimedia Commons
Leaf MinerWinding white or brown tunnels (mines) inside the leaf, or on beet, chard, spinach and celery large pale blotches that soon turn brown and papery.Photo: Flowersabc, CC BY-SA 2.0, Wikimedia Commons
Squash bugAdults are flat, grey-brown bugs about 1.6 cm long with orange-striped abdomen edges; young nymphs are pale green, older ones grey with dark wing pads.Photo: Pollinator at English Wikipedia, CC BY 2.5, Wikimedia Commons
Two-spotted spider miteTiny yellowish-green mites with two dark patches, white cast skins and eggs on the leaf undersides — easiest to see with a 10× hand lens.Also called: red spider mitePhoto: Gilles San Martin from Namur, Belgium, CC BY-SA 2.0, Wikimedia Commons
WhiteflyFlat, oval, creamy-white scale-like nymphs on the undersides of leaves; black nymphs have been killed by a parasitic wasp.Photo: gaucho, CC BY-SA 3.0, Wikimedia Commons

Diseases

Growing conditions

Blossom-end rotThe first fruits of the season are affected most often.Photo: A13ean, CC BY-SA 3.0, Wikimedia Commons

Which cucumber problems need quick action?

These spread or do lasting harm fast; check the plants and start treatment the day you see them.

Cucumber beetles: Chewed cotyledons, leaves and stems of young plants; scarred fruit rind on older plants.
Bacterial soft rot: Whole roots, tubers, bulbs, heads or fruit can collapse within a few days, often leaving only the skin — in the garden and in storage.
Bacterial wilt of cucurbits: Wilted leaves develop yellow and dead patches and shrivel.
Downy Mildew: A white, grey or purple mould on the underside of the leaf, directly below each blotch, in damp weather.
Fusarium wilt: A cut stem shows brown or reddish-brown water-conducting tissue — lines lengthways, dots or a ring in cross-section.
Grey mould: On strawberries, grapes and other soft fruit a soft brown rot, often as the fruit ripens; on gooseberries whole branches die.
Leaf Curl Virus: Plants are stunted and stay upright and bushy because the internodes are short; plants infected young are severely stunted.
White mould (Sclerotinia): Later, hard black seed-like bodies (sclerotia) 0.5–1 cm across in the mould and inside hollow stems.

Plants with many of the same problems

Which plants each problem affects: sources

The links between these problems and the plant were checked against these pages.