Why a weekly walk-round beats any spray

Most apple tree problems in British gardens are spotted far too late. By the time you notice curled tips or a maggot in the fruit, the insects responsible have already done the damage for this season and are tucked away preparing for the next. The good news is that the three pests you are most likely to meet — aphids, codling moth and winter moth — all give themselves away with visible clues if you know where to look.

Two minutes a week is enough. Take a slow circuit of each tree and check three zones in turn: the soft new growth at the shoot tips, the undersides of a handful of leaves across the canopy, and the swelling fruitlets. Do it in the evening if you can, when the light is behind the leaves and insects are active. Keep a notebook or a phone note of what you find and when, because pest timing shifts year to year with the weather and your own records quickly become the most useful guide you have.

Aphids: sticky, curled and usually obvious

Greenfly, and the rosy apple aphid that turns young leaves pink and crumpled, cluster on shoot tips and the underside of leaves. Woolly aphid is different — it hides on bark, especially around old pruning cuts and wounds, under a covering of white waxy fluff that looks like cotton wool.

Look for:

• Curled, puckered or blistered leaves at the tips of shoots, from May onwards
• Sticky honeydew on leaves and fruit, followed by a black sooty mould
• Ants marching up the trunk — they farm aphids and protect them from predators
• White waxy patches on bark and at the base of branches

Small colonies can simply be squashed or blasted off with a firm jet of water. A spray of horticultural soap on a dry, still evening will deal with heavier numbers, but it only works on contact, so it needs repeating. The better long-term answer is to make your tree a good place for ladybirds, hoverfly larvae and lacewings, and to put a grease band around the trunk to cut off the ants. Blue tits will clear astonishing numbers of aphids from a small tree if you give them a nest box nearby. For woolly aphid on bark, scrub the affected areas with a stiff brush over a spread sheet in winter, then destroy what you collect.

Codling moth: the grub in the core

The adult is a small, mottled grey-brown moth that flies at dusk from late May into July. It lays eggs on leaves and young fruit, and the newly hatched caterpillar tunnels in, usually through the eye end, and feeds its way towards the core.

Tell-tale signs include a neat hole with reddish-brown frass pushed out of it, brown tunnels when you cut the fruit open, and apples dropping early in late summer. In warm southern counties there is often a second generation, and that later wave causes most of the damage to ripening fruit.

The caterpillar overwinters in loose bark or in the leaf litter at the base of the tree, which is exactly where you can intercept it. Hang pheromone traps in late May to confirm when moths are flying, and wrap corrugated cardboard bands around the trunk from July. Larvae spin their cocoons in the corrugations; take the bands off in winter and burn them. Pick up fallen fruit every day through August and September, and clear leaf litter from under the canopy rather than letting it sit there until spring.

Winter moth: the one to catch in November

Winter moth is the pest that catches people out, because the damage appears in spring but the moment to act is late autumn. The female moth is grey and wingless and climbs the trunk in November and December to lay her eggs, while the males flutter around the tree. The tiny green caterpillars hatch in March, wriggle into swelling buds, then shred leaves as they grow, sometimes stripping a young tree's foliage and blossom entirely.

Fit a grease band around the trunk in October, before the females emerge, and keep it sticky and free of debris through the winter. Position it 45cm or so above the ground with a clear trunk above and below, and add a tree guard on young trees for extra protection. The caterpillars also drop to the soil to pupate in early summer, so encouraging ground beetles by leaving a light mulch under the tree, rather than bare, repeatedly hoed earth, helps keep numbers down year after year.

Other suspects worth a glance

• Apple sawfly: a maggot in young fruitlets with a ribbon-like scar around the skin; affected fruitlets drop in June.
• Capsid bug: tattered leaves with small holes, plus corky bumps on the fruit surface.
• Tortrix moth caterpillars: rolled leaves and silken webbing at shoot tips, usually minor.
• Spider mite: fine webbing and pale mottled leaves in hot, dry spells.

A simple year-round routine

In winter, inspect bark for overwintering stages, scrape loose flakes onto a sheet and dispose of them, and clear leaf litter from around the trunk. In early spring, check twice a week from bud burst for aphids and small caterpillars climbing towards the tips. Through late spring and summer, hang pheromone traps, keep grease bands working, and pick up fallen fruit daily. In autumn, finish by removing cardboard bands and any remaining debris before the moths return. Steady observation, repeated each year, does more for a garden apple crop than any single treatment.