Recognising Common Pear Tree Diseases and Disorders

Reading the signs early

Pear trees are generous, but they do not suffer neglect quietly. In a British orchard, whether you are growing dessert pears for the kitchen or sharp, tannic perry pears for cider, the first sign of trouble is often a change in leaf colour, fruit shape or shoot growth. A healthy pear tree should put on strong extension growth each spring, carry clean leaves through summer and hold its fruit until picking. When that rhythm falters, look closely. Early identification saves both crop and tree, and it is far easier to manage a problem in May than in September.

Scab, rust and other fungal problems

Pear scab is the most common fungal headache. It thrives in damp, mild weather and shows as velvety, olive-brown patches on leaves and young fruit. Later, those patches turn black and corky, and heavily infected fruitlets crack or drop. The fungus overwinters in fallen leaves and in lesions on twigs, so orchard hygiene matters.

• Scab: rake up and destroy fallen leaves; prune out congested growth to improve airflow; apply sulphur sprays from bud burst if the previous season was bad.
• Pear rust: bright orange spots on the upper leaf surface and raised, orange-brown aecia underneath. It needs juniper as an alternate host, so removing nearby juniper can help, though it is not always practical. Affected leaves usually fall early but the tree survives.
• Powdery mildew: white, mealy patches on shoots and leaves, often on young growth. Prune out affected tips and avoid excessive nitrogen.

Canker and fireblight: when to act fast

Pear canker is a slow, destructive fungal disease that kills bark and wood. Look for sunken, dead patches on branches and trunks, often with cracked or swollen edges. Small red pustules may appear in wet weather. Cankers girdle branches, cutting off sap and causing dieback. Cut out cankers in dry weather, cutting back to clean, healthy wood. Sterilise tools between cuts and burn or bin the prunings — never compost them.

Fireblight is more urgent. It is a bacterial disease that turns blossoms, leaves and shoot tips black as if scorched. Shoots often bend into a distinctive shepherd's crook. A creamy bacterial ooze may appear in warm, humid conditions. If you suspect fireblight, do not prune casually. Report it to the relevant plant health authority. If you are advised to remove material, cut at least 60cm below the visible symptoms, sterilise tools after every cut and destroy the material by burning. Do not move infected wood around the country.

Pests that spoil the crop

Not every problem is a disease. Several pests target pears specifically, and their damage can be mistaken for poor pollination or bad weather.

• Pear leaf blister mite: tiny mites cause raised, reddish or pale green blisters on leaves. Heavy infestations distort growth but rarely kill the tree. Encourage predatory mites and avoid broad-spectrum sprays.
• Aphids: curled, sticky shoot tips with honeydew and sooty mould. Ladybirds, lacewings and earwigs usually catch up. If not, wash colonies off with a strong jet of water.
• Pear midge: small maggots tunnel into young fruitlets, which swell, blacken and drop in early summer. Pick up and destroy fallen fruitlets, and cultivate the soil beneath the tree to disturb overwintering larvae.

Disorders that are not diseases

Sometimes the cause is physiological. Cork spot, often called bitter pit, shows as brown, corky patches just under the skin of otherwise sound-looking fruit. It is linked to calcium movement and irregular watering. Water consistently through dry spells, avoid heavy summer pruning and consider a foliar calcium feed if the problem repeats.

Stony pit virus causes fruit to become hard, gritty and misshapen. There is no cure. If a tree is badly affected, remove and replace it, and do not propagate from it. Waterlogging and drought both cause leaf yellowing, early leaf drop and poor fruit size. Pears dislike sitting in wet soil, so improve drainage before planting. Late frosts can blacken blossoms and young fruitlets, leaving a tree that looks diseased but is simply cold-damaged.

Practical orchard hygiene and cider-making choices

Good growing is the best defence. Plant pears on a suitable rootstock for your soil, choose varieties with some natural resistance where possible, and space trees so air moves freely. Prune in winter to remove dead, diseased and crossing wood, but leave fireblight pruning for expert advice. Keep the ground clear of fallen leaves and rotten fruit, especially around perry pear trees, because these are reservoirs for scab and pests.

For cider and perry makers, orchard hygiene continues into the harvest. Sort fruit before milling. Discard mouldy, rotten or heavily scabbed pears — they add off-flavours and can spoil a ferment. A little scab on the skin is not the end of the world, but brown rot and canker-infected fruit should never go into the press. Wash and dry fruit if it is dirty, and press within a few days of picking. Healthy, clean pears give cleaner juice, better fermentation and a cider you can be proud of.