What diseases affect lettuce?

Bacterial soft rot, Downy Mildew, Fusarium wilt, Grey mould, Tomato spotted wilt virus, White mould (Sclerotinia)

Lettuce pests and diseases: how to recognise them

Q: Which lettuce problems need quick action?

Bacterial soft rot: Potato stems may turn black and rot from the base upwards (blackleg). Downy Mildew: Badly affected leaves shrivel and turn brown or yellow and fall early; plants become stunted and some may die. Fusarium wilt: White, pink or orange fungal growth may appear on dead stems in wet weather; the whole plant usually dies. Grey mould: Small black seed-like bodies may form on the infected material. Tomato spotted wilt virus: Plants infected young often fail to flower or set fruit. There is no cure once a plant is infected. White mould (Sclerotinia): Roots, heads, pods and fruit can rot too, also in storage.

Lactuca sativa

The pests, diseases and disorders recorded for lettuce 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	9
Pests	2
Diseases	6
Nutrient deficiencies	1
Need quick action	6

How to grow lettuce · All pests and diseases

Pests

Leaf MinerHeavily mined leaves dry up or drop early; badly affected tomato plants can lose most of their leaves.Photo: Flowersabc, CC BY-SA 2.0, Wikimedia Commons
WirewormsThin, yellowish-brown larvae up to 25 mm long with three pairs of short legs behind the head in the soil.Photo: Alton N. Sparks, Jr., University of Georgia, Bugwood.org, CC BY 3.0, Wikimedia Commons

Diseases

Nutrient deficiencies

Boron deficiencyLeaf-tip dieback on lettuce; small, puckered leaves and distorted fruits on strawberries; dimpled pear skin with brown patches in the flesh.Photo: Jan Hinrichs-Berger, LTZ Augustenberg, CC BY 4.0, Wikimedia Commons

Which lettuce problems need quick action?

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

Bacterial soft rot: Small water-soaked spots that quickly enlarge, sink and turn soft and mushy; the tissue underneath is cream to black.
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: Wilting and yellowing that often starts on one side of the plant, a branch or even a leaf; lower leaves yellow first.
Grey mould: Fuzzy grey-brown mould on decaying buds, flowers, leaves, stems or fruit in humid weather.
Tomato spotted wilt virus: Young leaves with a bronze cast that later show small dark brown spots; leaves may cup or roll.
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.