Why Are My Chicory Leaves Curling?

Aphids

Peach-potato aphid (Myzus persicae) colonises the young leaves and growing tips of chicory, causing the newer leaves to curl and pucker around the feeding colonies. Lettuce root aphid (Pemphigus bursarius) attacks below ground and causes general wilting and yellowing of the whole plant without visible insects on the leaves. Both species are most active in spring and summer and reduce in the cooler autumn months when chicory is typically at its most productive.

What to do

• Inspect the undersides of young leaves and growing tips from April to August. Apply insecticidal soap to peach-potato aphid colonies. Grow under fine mesh to reduce colonisation by winged aphids. For lettuce root aphid, remove and destroy affected plants and avoid replanting the chicory family in the same bed for at least two years.

Downy mildew

Downy mildew (Bremia lactucae) affects chicory in cool, damp conditions, most often in autumn and in protected growing spaces (cloches, cold frames). It produces angular yellow patches on the leaf surface with a soft grey mould on the undersides. Affected leaves curl and become limp. Chicory is generally more tolerant of downy mildew than lettuce, but severe infections on young plants can cause significant damage.

What to do

• Space plants to allow air circulation. Water at the base rather than overhead. Remove and bin infected leaves. Improve ventilation under protection. Grow disease-resistant varieties where available for the autumn-winter protected crop.

Sclerotinia

Sclerotinia rot (Sclerotinia sclerotiorum) causes a wet, slimy rot at the crown of chicory plants, with characteristic white fluffy mould and hard, irregular black bodies (sclerotia) at the base of the rotted tissue. Outer leaves collapse outward and curl as they die. Sclerotinia is most common in cool, wet conditions and in the same soil where susceptible crops have previously been grown. The sclerotia persist in soil for many years.

What to do

• Remove and destroy affected plants immediately. Do not compost sclerotinia-affected material. Rotate chicory and related crops (lettuce, endive, celery, beans) away from affected soil for at least 3 to 4 years. Improve drainage in heavy, wet soils.

Mosaic virus

Lettuce mosaic virus (LMV) and other mosaic viruses cause mottled yellow-green patterning, leaf curl, puckering, and stunted growth on chicory. Infected plants do not recover. LMV is spread by aphids and by infected seed; using certified virus-free seed and controlling aphids are the main preventive measures.

What to do

• Remove and destroy infected plants. Control aphid vectors. Use certified virus-free seed for future crops. Do not save seed from chicory plants that show mosaic symptoms.

Frequently asked questions

Why are my chicory leaves curling?

Chicory (Cichorium intybus) leaves curl most commonly because of aphid infestation, downy mildew, or sclerotinia rot. Chicory is generally more robust than lettuce and endive, but the same pests and diseases affect it. Aphids (particularly peach-potato aphid and lettuce root aphid) colonise the young leaves and growing tips, causing curling and puckering of newer growth. Downy mildew (Bremia lactucae) produces angular yellow patches on the upper leaf surface with a grey-white mould on the undersides and causes leaf curling as the affected tissue collapses. Sclerotinia (Sclerotinia sclerotiorum) causes a wet rot at the crown of the plant, producing white fluffy mould and hard black bodies (sclerotia) at the base of the leaves: affected leaves collapse and curl outward as the crown rots. In forcing chicory for chicons (witloof), leaves may curl during the blanching process due to overcrowding, uneven heat, or excessive moisture.

How do I grow chicory in the UK?

Chicory (Cichorium intybus) includes several distinct types grown in the UK for different purposes. Green-leaved chicory and radicchio types are grown as salad leaves, sown from May to July and harvested through autumn and winter. Witloof (forcing chicory) is sown in May to June, grown as a leafy plant through summer to build up a substantial root, then the roots are dug in autumn and forced in warmth and darkness to produce pale, crisp chicons in winter. Grow chicory in fertile, well-drained soil in full sun; it tolerates poorer conditions than lettuce and is very hardy once established. Sow thinly and thin to 30 centimetres apart. Water regularly in dry conditions. Chicory is significantly more cold-hardy than lettuce and can provide harvests through much of the UK winter with minimal protection; a cold frame or cloche extends the season further. The perennial nature of the plant means roots can be overwintered and regrow in spring if left in the ground.

How do I force chicory for chicons?

Forcing chicory (witloof) to produce chicons is a two-stage process. In the first stage (summer), sow witloof chicory seed in late May or June and grow on as a leafy plant through the summer. In autumn (October to November), dig up the roots, which should be 2 to 4 centimetres in diameter and 20 to 30 centimetres long. Trim the leafy tops to within 2 to 3 centimetres of the crown and trim the root to approximately 20 centimetres. Pack the roots upright in a box or large pot of barely moist compost, cover with another pot or cardboard to exclude all light, and place in a warm (15 to 18°C) position. The blanched chicons emerge from the crown over the next 3 to 5 weeks, growing pale, compact, and bittersweet in the complete darkness. Harvest when 10 to 15 centimetres long by cutting at the base. The roots often produce a second, smaller chicon if returned to darkness. Force roots in batches every few weeks from October to February for a sustained supply.

Why are my chicory leaves turning yellow?

Chicory leaves turn yellow because of downy mildew (angular yellow patches with grey mould on the undersides), lettuce mosaic virus (mosaic yellow-green patterning and leaf curl), nitrogen deficiency (uniform pale yellowing and slow growth, treat with a balanced liquid fertiliser), natural ageing of older outer leaves (normal, progressive yellowing from the outside inward), or waterlogging and crown rot (yellowing and collapse starting from the outer leaves, with rotting at the crown). Bolting in hot conditions causes the leaves to become small, yellow-tinged, and bitter as the plant diverts resources to flower production. In witloof chicory, yellowing of the emerging chicons during forcing indicates too much light: exclude all light more thoroughly.