What pests attack watermelon?

Cucumber beetles, Two-spotted spider mite, Whitefly

What diseases affect watermelon?

Downy Mildew, Fusarium wilt, Leaf Curl Virus, White mould (Sclerotinia), Anthracnose, Verticillium wilt

What else goes wrong with watermelon?

Blossom-end rot, Fruit cracking

Watermelon pests and diseases: how to recognise them

Q: Which watermelon 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. 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: White, pink or orange fungal growth may appear on dead stems in wet weather; the whole plant usually dies. Leaf Curl Virus: Young leaves are small, curl upward and look crumpled, with yellowing between the veins and along the margins. White mould (Sclerotinia): Roots, heads, pods and fruit can rot too, also in storage.

Citrullus lanatus

The pests, diseases and disorders recorded for watermelon 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	11
Pests	3
Diseases	6
Growing conditions	2
Need quick action	5

How to grow watermelon · 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
Two-spotted spider miteLeaves turn yellow or reddish, dry up and drop; badly attacked plants weaken and may die. Worst in hot, dry, dusty conditions.Also called: red spider mitePhoto: Gilles San Martin from Namur, Belgium, CC BY-SA 2.0, Wikimedia Commons
WhiteflyLeaves yellow, dry or drop where many nymphs feed; some whiteflies cause silvering or spread viruses in vegetables.Photo: gaucho, CC BY-SA 3.0, Wikimedia Commons

Diseases

Growing conditions

Which watermelon 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.
Downy Mildew: A white, grey or purple mould on the underside of the leaf, directly below each blotch, in damp weather.
Fusarium wilt: Wilting and yellowing that often starts on one side of the plant, a branch or even a leaf; lower leaves yellow first.
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): A soft, wet rot on stems, often near soil level; plants suddenly turn yellow, wilt and collapse.

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.