chestnut blight

Symptoms

Sunken orange-brown cankers on bark with cracked + raised edges, bright orange fungal stromata (pinhead-sized) embedded in canker surface, complete girdling + death of branches above canker within 1-2 years, characteristic epicormic sprouts below canker after upper branch dies, eventual tree death over 3-8 years in classical virulent strains.

Easily confused with

• Asian chestnut gall wasp

  How to tell them apart: Cryphonectria parasitica (chestnut blight) makes sunken-to-cracked, bright-brown bark cankers that girdle and kill whole branches; on the cankered bark you see erupting orange to orange-yellow fruiting bodies (and orange spore tendrils in damp weather), pale-brown mycelial fans under the bark, and dead brown leaves that wilt but stay hanging above the canker. Dryocosmus kuriphilus (oriental chestnut gall wasp) instead makes discrete 8-20 mm swellings (galls) on spring buds, shoot tips, leaf midribs and petioles, first green to rose-red, later drying to hard woody brown galls that cling to the twigs for years - with no bark canker, no orange stromata and no clinging dead leaf curtain. Read the bark: a sunken cracked canker with orange pustules is blight; a round green-to-brown lump on a bud or leaf-rib is the gall wasp. Both are regulated in EU protected zones, so in a protected-zone area confirm and report suspected blight to your national plant protection authority (NPPO).