Common causes of cankers
Annulohypoxylon canker, or Hypoxylon canker
Many hosts, but in California reported primarily on oaks and tanoak.
Anthracnose
Associated with leaf spots and distorted terminals.
Bacterial blight
Bark oozes during wet weather; elongated lesions may appear on twigs.
Botryosphaeria canker and dieback
Limbs and branches die back on many hosts, wounds ooze on some hosts.
Canker rots
Mostly oaks and other broadleaf trees. Surface cankers are associated with wood decay.
Chinese elm anthracnose
Affects only Chinese elm (Ulmus parvifolia), mostly in coastal areas.
Cypress canker
Affects cypress and sometimes arborvitae, Chamaecyparis, and juniper.
Cytospora canker
Many hosts, often causes sunken, elliptical lesions.
Ficus canker
Kills frequently pruned, drought-stressed Indian laurel fig.
Fire blight
Preceded by twig and leaf damage, affects some plants in Rosaceae family.
Foamy bark canker
Causes discolored, oozing bark and dieback of coast live oak.
Foamy canker, or alcoholic flux
White, frothy exudate from bark of elm, liquidambar (sweet gum), oak, and Victorian box.
Injuries
Many causes, e.g., equipment or vehicle impact, pruning.
Nectria canker
Many hosts; wilted foliage appearing first in the spring is a common symptom.
Oak branch canker and dieback
Diplodia dieback affects many oaks, especially coast live oak in southern California.
Phytophthora root and crown rot
Wilting, foliage discoloration, and premature defoliation are common symptoms.
Pine rusts
Cause blistered, oozing, or swollen pine bark; may discolor or spot needles.
Pitch canker of pines
Pine branches turn reddish, die back.
Pruning wounds
Caused by pruning large limbs or by improperly making cuts.
Raywood ash canker and decline
Botryosphaeria canker when host is drought stressed.
Septoria canker
Affects poplars; leaf spots are present.
Sooty canker
Weak, secondary pathogen of many stressed hosts.
Sudden oak death
Kills certain true oaks (in red and intermediate oak subfamilies) and tanoak.
Sunburn
Defoliated, severely pruned, and young trees commonly are affected.
Sunscald
Winter injury to bark, occurs in mountainous areas and high valleys of eastern California.
Sycamore canker stain
Infects only sycamore and London plane.
Underwatering
Plants are most susceptible to sunburn from heat and light if they lack sufficient water.
Walnut thousand cankers
Bark-beetle vectored fungus kills black walnuts.
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