Fire blight

📖 Overview

Fire blight is a devastating bacterial disease caused by Erwinia amylovora that attacks the flowers, shoots and branches of apple, pear, quince and related ornamental trees. The infection moves rapidly through the plant, causing leaves and twigs to suddenly blacken and wither as if burned by fire, with affected branch tips characteristically curling into a shepherd's crook shape. What makes fire blight particularly serious is its speed and the permanence of the damage: once a branch is infected, there is no cure, and the disease can kill an entire tree within a single growing season if left unchecked.

This disease strikes hardest during spring and early summer, typically between April and June in temperate climates, when trees are flowering and new growth is tender. The first visible sign is usually the sudden wilting and browning of flower clusters, followed within days by blackening of the young twigs behind them. You may also notice a distinctive milky or amber-colored bacterial ooze seeping from cracks in the bark, especially after rain. The shepherd's crook appearance of dead branch tips is the most characteristic symptom and distinguishes fire blight from other branch diseases like winter frost damage, which tends to affect the entire branch uniformly and lacks the shepherd's crook bend.

Fire blight is of critical concern to home gardeners because it is a regulated quarantine disease in the European Union and must be reported to your local plant protection authority (in Hungary, to NÉBIH) if suspected. The disease spreads through flower visits by pollinating insects, water splash during rain, and pruning wounds, making spring the most dangerous window. While resistant varieties exist for some host plants, early detection and immediate, drastic action are your only reliable defenses.