Why Are My Nectarine Leaves Curling?

Peach leaf curl (Taphrina deformans)

Peach leaf curl is caused by Taphrina deformans, a fungus that overwinters on the bark and in the buds of infected trees. As the buds begin to swell in late winter and early spring, the spores are released and infect the emerging leaf tissue during wet weather. The infection causes cells in the developing leaves to multiply abnormally, producing thick, puckered, curled, and blistered leaves with vivid red, pink, orange, and white colouration. The colour comes from anthocyanin pigments that the infected cells produce in response to the fungal invasion. As the season progresses, the infected leaves develop a white or powdery spore-coating, yellow, and then fall. The tree produces a second flush of clean growth after the infected leaves drop.

Without protection, most nectarine trees in UK outdoor positions will suffer significant leaf curl in most years. The wet, mild conditions that prevail during bud burst in February to April in the UK are almost ideal for spore infection. Trees that suffer repeated annual defoliation weaken progressively and produce smaller crops.

What to do

• Remove and destroy infected leaves as soon as they appear to reduce spore return to the bark, though this does not prevent the current-year infection.
• Apply copper fungicide (Bordeaux mixture or copper oxychloride) in late January to early February, before any bud swelling is visible, and again in November as the leaves fall. These are the two preventive treatment windows.
• After defoliation, feed the tree with a balanced fertiliser to support the second flush of growth.

Prevention strategies for UK nectarines

The most effective long-term approach to peach leaf curl on UK nectarines is to keep the bark and buds dry during the infection period using a physical rain shelter. A polythene cover erected over a fan-trained nectarine from November to late May prevents rain from reaching the tree during the critical window when spores are released and buds are vulnerable. The shelter must be overhead protection: side panels can be omitted if there is no driving rain from the side, but the top must shed rain away from the tree canopy. This approach eliminates leaf curl entirely in most years and is strongly recommended for fan-trained nectarines on south-facing walls.

For free-standing trees, a rain shelter is impractical and copper spray is the only option. In very wet springs, even copper spray may not prevent all infection; accept some leaf curl in these years, remove infected leaves, and focus on maintaining the tree's vigour with good feeding.

Aphids

Peach-potato aphid (Myzus persicae) and other aphid species colonise nectarine shoot tips in spring, causing the young leaves to curl and distort. On outdoor trees this is typically secondary to leaf curl; on trees grown under glass, where leaf curl is less of an issue, aphids may become a more significant problem. Inspect the growing tips regularly from April and treat colonies with insecticidal soap before the leaves curl around the insects.

Red spider mite

Two-spotted spider mite (Tetranychus urticae) can affect nectarine grown under glass or against a warm wall, causing bronze stippling on the leaves and fine webbing on the undersides. Maintain humidity around glasshouse trees and introduce predatory mites (Phytoseiulus persimilis) for biological control. Regular leaf inspection from April allows early detection before populations reach damaging levels.

Frequently asked questions

Why are my nectarine leaves curling?

Nectarine leaves curl almost exclusively because of peach leaf curl, a fungal disease caused by Taphrina deformans. Nectarine is a smooth-skinned variant of peach (Prunus persica var. nucipersica) and is equally susceptible, if not more so, to peach leaf curl. The fungus infects the leaves as they emerge from the buds in early spring during wet, mild weather, causing them to pucker, thicken, curl, and develop vivid red, pink, yellow, or white blistering and distortion. Infected leaves eventually yellow and fall, sometimes leaving the tree partly defoliated by early summer. The tree then produces a second flush of growth that emerges clean. As with peach, there is no curative treatment once the leaves show symptoms: all effective management is preventive, applied before the buds begin to swell in late winter.

Is nectarine more susceptible to leaf curl than peach?

Nectarine and peach are affected by the same pathogen (Taphrina deformans) and have similar levels of susceptibility. In practice, many growers find nectarines suffer more visibly from peach leaf curl in the UK, partly because nectarines are often grown in slightly more exposed positions than fan-trained peaches against walls, and partly because the smooth skin of the fruit makes any associated damage more visible. The prevention and control measures are identical for both: copper fungicide spray in late winter and again in autumn, and a polythene rain shelter erected from November to May for fan-trained trees. Growing nectarine under glass almost eliminates peach leaf curl, since the disease requires wet conditions at bud burst to establish.

How do I protect my nectarine from leaf curl?

The two effective approaches for protecting nectarine from peach leaf curl are: (1) Copper fungicide spray applied in late January to February, before any bud movement is visible on the tree, and again in November as the leaves fall. Use a copper-based product (Bordeaux mixture or copper oxychloride). Do not spray after bud burst: the treatment must be in place before the spores can infect the emerging leaf tissue. In wet winters, applying a third application in December provides extra protection. (2) A polythene rain shelter: erect a simple framework of polythene sheeting over a fan-trained nectarine from November to late May. The shelter must keep the bark and buds dry throughout the infection period; the sides can be left open to allow airflow but the overhead cover must prevent rain reaching the tree. This approach eliminates leaf curl entirely without any spray, as the fungal spores require wet conditions to infect the bud tissue.

Can nectarine be grown outside in the UK?

Yes, nectarine can be grown outside in the UK, but it requires a sheltered, south or south-west facing position against a warm wall to ripen fruit reliably, particularly in the midlands and north. In the south and south-east of England, nectarines can be grown as free-standing trees in sheltered spots, though fan-training against a sunny wall gives consistently better results. The main outdoor challenge is peach leaf curl, which is almost universal on unprotected nectarine trees in the UK due to the wet spring weather. Growing against a south-facing wall under a rain shelter addresses both the ripening and leaf curl problems simultaneously. Varieties recommended for UK outdoor growing include 'Lord Napier' (the most reliably hardy and productive outdoor nectarine in the UK), 'Early Rivers', and 'Humboldt'. Nectarines grown under glass require little protection from leaf curl but need careful attention to watering, feeding, and hand-pollination.