Chaenomeles Leaves Curling
Powdery mildew and aphids are the most common reasons chaenomeles leaves curl. This guide shows you how to identify each cause and keep flowering quince healthy through the season.
1. Powdery mildew
Powdery mildew is the most frequently seen disease on chaenomeles in UK gardens. Several fungal species cause it, with Podosphaera oxyacanthae being the most common. The infection is favoured by warm, dry days combined with cool, humid nights, and spreads rapidly through the canopy during summer.
What to look for
A white or grey powdery coating appears on the upper surface of young leaves. Affected leaves curl upward or cup inward, and new shoot growth becomes distorted and may fail to elongate normally. Flower buds can also be affected, reducing the next season's display. The overall effect on a heavily infected plant is a greyish, unkempt appearance.
What to do
Remove and bin affected shoots as soon as you see them to limit the spread of spores. Avoid feeding plants heavily with high-nitrogen fertiliser as soft, sappy new growth is the most susceptible. Improve air circulation by thinning congested shoots after flowering. A fortnightly spray of a solution of one part whole milk diluted in nine parts water has been shown in trials to reduce powdery mildew significantly. Alternatively, a sulphur-based fungicide applied from late spring works well as a preventive. Avoid overhead watering late in the day.
2. Aphids
Several aphid species colonise chaenomeles, including rosy apple aphid (Dysaphis plantaginea) and various green aphids. They congregate on the growing tips and undersides of young leaves in spring and early summer, feeding on sap and causing the characteristic leaf curl that shelters them from predators and sprays.
What to look for
Young leaves at the shoot tips curl tightly and may appear crinkled or puckered. Part the curled leaves and you will find clusters of pale green, yellow, or pinkish aphids feeding on the undersides. A sticky honeydew deposit on leaves below the colony and black sooty mould on that honeydew are further signs. Ants walking up and down the stems are often a clue that aphids are present above, as ants farm aphids for their honeydew.
What to do
Squash small colonies by hand or knock them off with a firm jet of water from a hose early in the morning. Check every three to four days and repeat, as new aphids hatch constantly. For persistent infestations, spray with a plant-based fatty acid or horticultural soap solution, taking care to penetrate inside the curled leaves where colonies shelter. Encourage natural aphid predators by planting nectar-rich flowers nearby and avoiding broad-spectrum insecticides. Ladybirds, hoverfly larvae, and blue tits will tackle colonies effectively once they establish.
3. Fire blight (Erwinia amylovora)
Fire blight is a serious bacterial disease of plants in the rose family. As a member of Rosaceae, chaenomeles is susceptible, though it is less commonly affected than apples, pears, and cotoneasters. The bacterium spreads through rain splash and insects visiting flowers, entering through blossoms and wounds.
What to look for
Affected shoot tips die back rapidly and bend into a distinctive shepherd's crook shape. The leaves on these shoots shrivel, turn dark brown or black, and remain attached to the dead wood rather than dropping cleanly. The dead tissue has a scorched appearance, as if burned, hence the name. In wet weather a bacterial ooze may be visible on affected tissue. The infection can spread rapidly down branches in warm, wet spring conditions.
What to do
Cut out all infected material immediately, pruning at least 30 cm below any visible discoloration into completely healthy wood. Sterilise your tools with a 10 percent bleach solution between every cut to prevent spreading the bacterium on your tools. Bin all removed material; never compost it. Avoid feeding the plant with high-nitrogen feeds in late spring as this encourages the soft, sappy growth most vulnerable to infection. Fire blight is a notifiable plant disease in Great Britain; if you suspect a case, report it to the Animal and Plant Health Agency (APHA).
4. Drought stress
Chaenomeles is often planted as a wall shrub, particularly on north and east facing aspects where it performs admirably. However, the soil at the base of a wall is frequently dry because the wall deflects rainfall and the foundations absorb moisture. Summer drought is therefore a surprisingly common problem even on apparently moist sites.
What to look for
Leaves curl inward and their margins may scorch and turn brown, beginning at the tips. Foliage takes on a dull, slightly grey-green tone rather than its usual glossy green. Leaves may drop early, beginning with the oldest lower leaves. On wall-trained plants the problem is often worst on the side closest to the wall where the soil is driest.
What to do
Water deeply at the base of the wall once a week during dry spells, directing water away from the base of the wall and out toward the root zone, which extends well beyond the canopy. Mulch the root zone with a 100 mm layer of wood chip or composted bark, keeping it clear of the stem, to conserve moisture and reduce temperature fluctuations. An annual spring application of a balanced slow-release fertiliser improves the plant's ability to cope with dry periods. Wall-trained chaenomeles may benefit from irrigation even in relatively wet summers if rainfall is intercepted by the canopy above.
5. Chaenomeles leaf spot (Diplocarpon mespili)
Entomosporium leaf spot, caused by the fungus Diplocarpon mespili (formerly Entomosporium mespili), affects many members of the rose family including chaenomeles, photinia, and loquat. It is most troublesome in wet seasons and on plants in poorly ventilated positions.
What to look for
Small, circular, reddish-brown or purple spots with a darker border appear on the upper surface of leaves. As the infection progresses the spots enlarge and merge, and the surrounding leaf tissue yellows. Severely affected leaves curl at the margins, turn entirely yellow, and drop early. The plant can suffer significant defoliation by midsummer in bad years. New growth emerging after defoliation may also be infected if wet conditions continue.
What to do
Collect and bin all fallen leaves in autumn to remove the overwintering source of spores. Prune to improve air circulation through the shrub. Avoid overhead watering. Where leaf spot is a persistent problem, spray with a copper-based fungicide or a myclobutanil-based product at bud burst in spring and repeat every two to three weeks during wet weather. Improving the overall vigour of the plant through appropriate feeding and watering reduces the severity of attacks in subsequent seasons.
Frequently asked questions
Why are my chaenomeles leaves curling and turning white?
White powder on curling leaves is almost certainly powdery mildew. The fungal coating and the associated distortion of young shoot growth are the two main signs. Powdery mildew on chaenomeles is rarely fatal but it weakens growth and can spoil the appearance of plants grown as a feature shrub.
Can chaenomeles get fire blight?
Yes. As a member of the rose family (Rosaceae), chaenomeles is susceptible to fire blight (Erwinia amylovora). Look for shoots that die back suddenly from the tip and bend into a shepherd's crook shape, with the dead leaves remaining attached and turning dark brown. Report confirmed fire blight to the relevant plant health authority as it is a notifiable disease in the UK.
How do I get rid of aphids on chaenomeles?
Rub aphid colonies off with your fingers or knock them off with a strong jet of water from a hose. Repeat every few days for two to three weeks. If colonies are large, spray with a plant-based insecticidal soap, targeting the undersides of curled leaves where aphids shelter. Encourage natural predators such as ladybirds and blue tits by avoiding broad-spectrum insecticides.
Why is my wall-trained chaenomeles losing leaves in summer?
Wall-trained chaenomeles are prone to drought stress because the wall creates a rain shadow and the soil at its base dries out quickly. Drought causes leaf scorch, curling, and premature leaf drop in summer. Water deeply at the base of the wall rather than against the brickwork, and mulch the root zone well.
Is chaenomeles leaf spot the same as apple scab?
They are caused by related but different fungi. Apple scab is Venturia inaequalis; chaenomeles leaf spot is usually Diplocarpon mespili or Entomosporium mespili. Both cause dark spots, yellowing, and early leaf drop, but they will not spread between apples and chaenomeles in your garden.
Find the best spot for your plants
Plant Compass maps the sun path across your windows so you know exactly which plants will thrive in each spot before you buy. Coming soon to the App Store.
Learn more