Plant problems

Why Are My Loquat Leaves Curling?

Q: Can I grow loquat in the UK?

Loquat (Eriobotrya japonica) can be grown in the UK in sheltered gardens, particularly in mild coastal areas and cities. It is one of the most dramatic and exotic-looking trees that is genuinely achievable outdoors in UK conditions; the very large, deeply veined, corrugated, dark green leaves up to 30 cm long give it a tropical appearance, and it flowers in autumn or early winter with sweetly scented cream flowers. In mild parts of the UK (Cornwall, Devon, coastal Wales, London and the south-east) it can be grown as a moderately large tree or tall shrub outdoors; in colder areas it is better kept as a wall-trained specimen against a south- or southwest-facing wall, or grown in a large container that is brought under cover in winter. Loquat tolerates temperatures down to about -10°C for brief periods; in the severe winters that occur occasionally in the UK (2010-2011 was -17°C in parts of England), established loquat can be killed to the ground. The orange, apricot-flavoured fruit ripens in May and June in favourable UK locations, making it among the first fresh fruit of the year; reliable outdoor fruiting is achievable in Cornwall and other very mild areas but is inconsistent further north. The fruit flowers are produced in autumn and can be damaged by UK autumn frosts before they open; fruit set is therefore more reliable indoors or in a cold greenhouse in most of the UK.

Q: What does loquat taste like?

Loquat (Eriobotrya japonica) has a sweet, mildly acidic flavour with notes of apricot, peach, and plum; the texture of the ripe fruit is similar to a very ripe apricot or plum, soft and juicy with a thin skin. The flesh is pale orange to yellow-orange, surrounds two or three large, smooth, glossy brown seeds (which should not be eaten, as they contain small amounts of cyanogenic compounds), and is very juicy and refreshing when fully ripe. The best loquats have an excellent sweet-tart balance and a distinct floral note; commercially grown loquats from Spain and China (available in UK Asian and Mediterranean grocers from spring) are often harvested before fully ripe and can be disappointing, with a firmer, sourer texture than the tree-ripened fruit. UK-grown loquats eaten straight from the tree in May, fully ripe and warm from the sun, are considered by those who have tasted them to be significantly superior to any imported version. Loquat jam and loquat liqueur are traditional preparations in parts of Spain and southern France where the tree is grown commercially; the seeds can be roasted and used as a coffee substitute.

Q: How do I treat fireblight on loquat?

Fireblight (Erwinia amylovora) on loquat is treated by removing all infected wood well below the visible symptoms. The bacteria travel systemically through the plant's vascular system faster than the visible browning, so cuts must be made at least 30 to 60 cm below the last visible brown tissue; the cut wood should show clean, white tissue with no brown staining. Disinfect pruning tools between each cut by dipping them in a 10% bleach solution or methylated spirits for at least 30 seconds; fireblight is highly infectious and can be spread mechanically from tree to tree on contaminated tools. All removed wood should be bagged and disposed of in the household waste; do not compost it. There is no curative chemical treatment for fireblight; copper-based bactericides applied preventively during flowering can reduce infection, but infected wood must be removed. In severe cases where more than a third of the tree is affected, removal of the whole tree may be necessary to prevent spread to nearby Rosaceae plants (apple, pear, quince, medlar, hawthorn). Report severe suspected fireblight to the RHS or APHA plant health teams if asked, as it remains a notifiable disease in the UK in commercial orchards.

Loquat (Eriobotrya japonica) is a dramatic evergreen tree from China and Japan with very large, deeply veined, corrugated leaves up to 30 cm long and sweetly scented cream flowers in autumn. One of the most striking exotic-looking trees that can be grown outdoors in mild UK gardens, it produces clusters of orange, apricot-flavoured fruit in May and June, often the first fresh fruit of the season in Cornwall and coastal southwest England. When the distinctive large leaves curl, scale insects on the leaf undersides or cold-weather damage are the most likely explanations.

Scale insects

Scale insects are the most common and persistent pest of loquat in UK conditions. Soft scale (Coccus hesperidum) and brown scale (Parthenolecanium corni) cluster on the stems and on the undersides of the large, corrugated leaves, particularly along the prominent midrib; they produce copious sticky honeydew that drips onto lower leaves and supports the growth of black sooty mould. Infested leaves lose their glossy appearance, yellow, and curl downward; in a severe infestation the whole canopy becomes coated in sooty mould and the tree's vigour declines. The large, leathery leaves of loquat make scale relatively easy to overlook along the pale undersides until populations are well established.

What to do

Inspect the leaf undersides thoroughly in autumn and again in early spring. Scrub scale off stems and leaf midribs with a toothbrush and insecticidal soap solution. Apply a horticultural oil or insecticidal soap spray to all plant surfaces, thoroughly covering the leaf undersides. Introduce Metaphycus helvolus (a parasitoid wasp) for biological control of soft scale. In late winter when the tree is dormant (and before the new season's scale nymphs hatch), a thorough spray with a plant oil winter wash is very effective at reducing the overwintering population.

Cold damage

Loquat is marginally hardy in most of the UK; established trees tolerate temperatures around -8 to -10°C for short periods, but a hard winter will cause the large leaves to brown at the margins and curl, and may damage the current season's growth significantly. Flower buds and open flowers (which appear in autumn) are killed by temperatures below -2°C, which limits outdoor fruiting to the very mildest UK areas. In the severe winters of 2010-2011 in parts of England, temperatures reached -17°C and many loquat trees were killed to the ground or completely; those that survived regenerated from the base.

What to do

In colder UK gardens (Zone H4 and below), grow loquat against a south- or southwest-facing wall for frost protection, or in a large container that can be moved under cover in winter. Protect with horticultural fleece during forecast frosts below -5°C. Cold-damaged leaves do not recover; remove them and allow the tree to produce new growth. Established trees in mild areas usually recover from moderate cold damage if the roots and main stem survived.

Fireblight

Fireblight (Erwinia amylovora) is a serious bacterial disease of the Rosaceae family to which loquat belongs. Infected shoot tips wilt suddenly and the leaves turn brown, curl, and remain on the branch rather than dropping (giving the characteristic 'blighted' appearance); the infected shoot bends into a distinctive shepherd's crook shape. A brown staining can be seen inside the infected wood when cut. Fireblight spreads rapidly from tree to tree in wet, warm conditions, particularly during the flowering period; bees, rain splash, and contaminated tools are the main transmission routes.

What to do

Remove infected wood at least 30 to 60 cm below the last visible browning. Disinfect pruning tools between each cut with bleach solution or methylated spirits. Bag and dispose of all removed wood; do not compost. There is no curative treatment; copper-based bactericides applied preventively during flowering can reduce new infection. In severe cases, remove the whole tree to protect nearby Rosaceae plants (apple, pear, quince).

Root rot

Loquat is vulnerable to Phytophthora root rot in waterlogged or poorly drained soils, particularly in the wet UK winters. Root rot causes yellowing and wilting of the foliage from the outside of the canopy inward; the large leaves yellow, droop, curl, and drop. The roots, when examined, are brown and mushy rather than white and firm. Loquat in a container in a saucer of standing water is particularly vulnerable.

What to do

Grow loquat in free-draining soil or compost; never allow the roots to sit in standing water. In clay soils, improve drainage by adding grit to the planting area. Container plants must have drainage holes and should not sit in saucers of water. If root rot is suspected, examine the roots, remove any mushy material, dust cut surfaces with sulphur, and repot in fresh compost. Allow the compost to dry somewhat between waterings.

Frequently asked questions

Why are my loquat leaves curling?

Loquat (Eriobotrya japonica) leaves curl most commonly in the UK because of scale insect infestation, cold damage, or fireblight. Scale insects cluster on the stems and leaf undersides, producing honeydew and sooty mould; infested leaves yellow and curl. Cold damage in hard winters causes the leaf margins to brown and curl. Fireblight (Erwinia amylovora) causes shoot tips to wilt suddenly, leaves to turn brown and curl and remain on the branch, and the shoot to form a shepherd's crook shape.

Can I grow loquat in the UK?

Loquat (Eriobotrya japonica) can be grown outdoors in mild UK gardens, particularly in Cornwall, Devon, coastal Wales, and south-east England. It tolerates temperatures to about -10°C when established. The dramatic, large corrugated leaves give a tropical effect. Orange, apricot-flavoured fruit ripens in May and June in mild locations. For colder areas, grow wall-trained or in a container moved under cover in winter. Flowers in autumn are damaged by frosts below -2°C, which limits outdoor fruiting in most of the UK.

What does loquat taste like?

Loquat has a sweet, mildly acidic flavour with notes of apricot, peach, and plum; the texture is similar to a very ripe apricot. The pale orange flesh is juicy and refreshing when fully ripe, surrounding two or three large, glossy brown seeds. Tree-ripened UK-grown loquats in May are significantly superior to the imported fruits available in supermarkets. Loquat jam and liqueur are traditional in parts of Spain and southern France; the seeds can be roasted as a coffee substitute.

How do I treat fireblight on loquat?

Remove all infected wood at least 30 to 60 cm below the visible browning; the cut wood should show clean white tissue. Disinfect pruning tools between cuts with bleach solution or methylated spirits. Bag and dispose of all removed wood; do not compost it. There is no curative treatment; copper-based bactericides applied preventively during flowering can reduce new infection. Protect nearby Rosaceae plants (apple, pear, quince) by removing severely infected loquat trees promptly.