Plant problems

Why Are My Cherimoya Leaves Curling?

Q: Why are my cherimoya leaves curling?

Cherimoya (Annona cherimola), also called custard apple, leaves curl most commonly in the UK because of mealybug infestation, cold temperatures, or root rot from overwatering. Mealybug (particularly Planococcus citri, the citrus mealybug) is the most persistent and damaging pest of Annona species in UK greenhouse conditions; the insects cluster in leaf axils, at stem joints, and on young leaves, producing white cottony deposits and copious sticky honeydew that supports sooty mould. Affected leaves curl and distort as the insects feed on the sap before the leaf tissue has fully expanded. Cold temperatures are the second major cause: cherimoya is from the Andean highlands of Peru and Ecuador and, while more cold-tolerant than most tropical fruit trees, suffers visible leaf curl and drop below 5°C. Root rot from overwatering in UK winter conditions causes yellowing and leaf drop that progresses from the base of the plant upward.

Q: How do I hand-pollinate cherimoya?

Cherimoya flowers are protogynous: the flower's female parts (stigmas) are receptive before the male parts (anthers) release pollen, which means a flower cannot pollinate itself. In the wild, the timing gap is bridged by small beetles that move pollen between flowers at different stages. In UK greenhouse conditions, hand-pollination is required. Each flower opens in two stages over two days: on the first day the flower opens partially with the petals slightly parted and the stigmas are receptive and sticky (the female stage); on the second day the flower opens fully and the anthers release cream-coloured pollen (the male stage). To pollinate, collect pollen from the anthers of a second-day flower using a small soft paintbrush and transfer it to the receptive stigmas of a first-day flower. Alternatively, collect pollen in a small container and store it in the refrigerator overnight, then apply it the following morning. Check the flowers daily during the flowering season (typically June to August in UK greenhouse conditions) and pollinate every day you find flowers in the receptive female stage.

Q: What does cherimoya taste like?

Cherimoya (Annona cherimola) has a rich, creamy, sweet flesh that blends the flavours of banana, pineapple, and strawberry with a texture often described as similar to custard or very ripe pear; the name 'custard apple' reflects this character. The flesh is white or cream-coloured, smooth, and melting when fully ripe; it surrounds several large, smooth, dark seeds that are inedible. The fruit should be eaten at room temperature when slightly soft to the touch (similar to a ripe avocado); underripe cherimoya is hard and astringent, while overripe fruit can develop an unpleasant fermented quality. Cherimoya is typically eaten fresh by halving and scooping the flesh with a spoon, avoiding the seeds. It can also be blended into smoothies, ice cream, and sorbet; cherimoya ice cream is considered a traditional treat in Spain and Latin America. The flavour deteriorates rapidly after the fruit is cut; eat it immediately. The skin and seeds are not edible and contain small amounts of annonacin, a compound present in most Annona species.

Cherimoya (Annona cherimola), known in English as custard apple, is a large-leaved subtropical tree from the cool Andean highlands of Peru and Ecuador. Unlike most tropical fruit trees, its highland origin makes it more cold-tolerant than expected, and it can be successfully grown in a lightly heated UK greenhouse or conservatory. Mark Twain called it "the most delicious fruit known to men." When the large, softly hairy leaves begin to curl, the most likely culprits are mealybug on the new growth or a cold spell below the plant's tolerance.

Mealybug

Mealybug (Planococcus citri and related species) is the most troublesome pest of cherimoya and other Annona species in UK greenhouse conditions. The insects appear as white, cottony clusters in leaf axils, at stem joints, and beneath the felty undersides of the large leaves. They extract sap from the plant and produce sticky honeydew that drips onto lower leaves and supports the growth of black sooty mould. When mealybug colonises young, expanding leaves, the affected tissue curls and distorts as it develops, a symptom that persists even after the insects are controlled. Heavy infestations cause leaf yellowing, premature drop, and a general weakening of the plant.

What to do

Dab mealybug colonies with a cotton bud soaked in methylated spirits to kill adults on contact. Apply insecticidal soap or neem oil spray to all affected parts, including the leaf undersides and stem joints. Introduce Cryptolaemus montrouzieri (the mealybug destroyer) or Leptomastix dactylopii (a parasitoid wasp) for biological control in heated glasshouses. Inspect the plant weekly; mealybug hides in crevices and populations rebuild rapidly if control is not maintained.

Cold damage

Cherimoya is considerably hardier than most tropical fruit trees, tolerating temperatures down to about 2°C when dormant. However, it is not frost-tolerant: a hard frost will damage the wood and kill young plants. In active growth, temperatures below 8°C cause the large leaves to yellow at the margins, curl, and drop; the tree responds to cold by accelerating its natural semi-deciduous leaf shedding. In a UK lightly heated greenhouse that drops to 3 to 5°C in winter, cherimoya will lose its leaves and go dormant, which is normal and not a sign of serious damage.

What to do

Maintain temperatures above 5°C at all times; above 15°C for active growth and fruiting. Accept winter leaf drop as normal if the temperature is kept just above freezing; reduce watering significantly while the tree is dormant. The tree will produce a new flush of foliage in spring as temperatures rise. Protect from frost at all times; a single hard frost can kill young cherimoya.

Root rot

Cherimoya does not tolerate waterlogged compost and is vulnerable to Phytophthora root rot if overwatered, particularly in winter when the plant is semi-dormant and its water uptake is greatly reduced. Root rot causes yellowing and leaf drop from the base of the plant upward; the compost will smell sour and the roots will be brown and mushy. This can easily be mistaken for cold-induced dormancy in winter, but the key distinction is that root-rotted plants show yellowing and collapse rather than a clean, graceful leaf shedding.

What to do

Reduce watering to a minimum in winter while the plant is dormant; the compost should be barely damp rather than wet. Grow in free-draining compost with added perlite. If root rot is confirmed, remove mushy roots, dust with sulphur, repot in fresh compost, and refrain from watering for 10 days. Resume watering only when the plant shows new bud growth in spring.

Powdery mildew

Powdery mildew can affect cherimoya in warm, dry conditions with poor air circulation, appearing as a white or greyish powdery coating on the young leaves and shoot tips, which curl and distort. The felty undersides of cherimoya leaves (a natural characteristic of the species) can make early mildew difficult to spot; look for the powdery coating on the upper leaf surface and on the young shoots. Mildew on cherimoya is less common than mealybug but can be significant in a dry summer.

What to do

Improve air circulation. Apply potassium bicarbonate or a sulphur-based spray at the first sign of infection. Ensure consistent watering; drought-stressed trees are more susceptible. Remove the most heavily affected leaves and dispose of them.

Frequently asked questions

Why are my cherimoya leaves curling?

Cherimoya (Annona cherimola) leaves curl most commonly in the UK because of mealybug infestation, cold temperatures, or root rot from overwatering. Mealybug is the most persistent pest of Annona species in UK greenhouse conditions; insects cluster in leaf axils and on young leaves, producing white cottony deposits and honeydew. Cold temperatures cause leaf curl and drop; below 2°C lasting damage occurs. Root rot from overwatering in UK winter conditions causes yellowing and leaf drop progressing from the base upward.

Can I grow cherimoya in the UK?

Cherimoya (Annona cherimola) is one of the more achievable subtropical fruit trees for UK greenhouse cultivation. Unlike its tropical relatives, cherimoya is from the cool Andean highlands and tolerates temperatures down to about 2°C when dormant, making it viable in a frost-free but unheated or lightly heated greenhouse. It requires full sun, free-draining compost, and moderate watering; it is partly deciduous in winter. Flowers require hand-pollination for fruit set indoors, as the natural beetle pollinators are absent in the UK.

How do I hand-pollinate cherimoya?

Cherimoya flowers are protogynous: the female parts are receptive before the male parts release pollen. On the first day a flower opens, the stigmas are receptive and sticky (female stage); on the second day the anthers release cream-coloured pollen (male stage). To pollinate, collect pollen from a second-day flower using a small soft paintbrush and transfer it to the receptive stigmas of a first-day flower. Check flowers daily during the flowering season (typically June to August in UK greenhouses) and pollinate every day you find receptive flowers.

What does cherimoya taste like?

Cherimoya has a rich, creamy, sweet flesh blending the flavours of banana, pineapple, and strawberry, with a texture often described as similar to custard. The white flesh is smooth and melting when fully ripe and surrounds several large dark seeds. Eat at room temperature when slightly soft to the touch; underripe fruit is hard and astringent. Cherimoya is best eaten fresh by halving and scooping with a spoon. It can also be blended into ice cream and sorbet. Mark Twain described it as "the most delicious fruit known to men."