Why Does My Pear Tree Have White Powder on the Leaves?

A white or silvery powdery coating on pear tree leaves and shoots is the unmistakable sign of powdery mildew. Unlike most fungal diseases, powdery mildew does not need wet conditions to spread — it actually thrives in warm, dry summers with high humidity. Identifying infected shoots early and pruning them out is the most effective management approach for pear trees.

Symptoms and spread

Powdery mildew on pear (Podosphaera leucotricha or related species) first appears as white powdery patches on young leaves and shoot tips. Infected young leaves often emerge narrow, cupped and distorted rather than opening flat and normally. As the season progresses, infected leaves may yellow and fall. Heavily infected shoot tips die back. The disease spreads by airborne spores produced on infected surfaces, and infection rate accelerates in warm weather with cool nights and fluctuating humidity.

Pruning out infected shoots

The most effective management step is pruning out every visibly infected shoot tip as soon as you see them in spring, before spores are released onto healthy growth. Cut back to a healthy bud below the infected section. Bag all prunings — do not compost them. Carry out a second inspection and pruning pass in summer if new infections appear. Over several seasons, consistent removal of infected shoots significantly reduces the quantity of disease in the tree.

Reducing susceptibility through management

Soft, fast-growing shoots produced after heavy pruning or excess nitrogen feeding are the most vulnerable to mildew infection. Moderate the amount of pruning you carry out in any single year, and reduce nitrogen applications to avoid producing a flush of soft growth. Improving air circulation through the canopy by opening up crossing or crowded branches reduces the humid microclimate that favours rapid spore germination.

Summer sprays

Sulphur-based fungicides, where permitted, have some curative and protective effect against powdery mildew. Sodium bicarbonate solution (1 tsp per litre of water with a drop of vegetable oil as a spreader) is a low-intervention option with mild preventative activity. Apply in the early morning on dry days. Neither chemical nor home-remedy sprays cure established infection — they reduce spore production and slow new infections. Pruning remains the most reliable approach.