Infection normally occurs through natural openings or external wounds induced through silvicultural practices, insects or weather conditions. Symptoms of infected tree hosts include leaf discolouration and wilting which eventually leads to death. The stems produce cankers and exude gum at infection sites and internal infections in the stem are visible as dark brown to black streaks in the cambium.
Fungal sexual structures (ascomata) can be observed by means of a hand lens, at the sites of infection on the stem. The ascomata have a round base, long necks and sticky white or yellow spore masses at the top. A fluffy mycelial growth can also be observed on the surface.
The spore masses of Ceratocystis are often be distributed via insect vectors. It can also be present in the frass created by insects; the frass can be distributed via wind and rain. Fungal spores can survive for long periods of time in the soil and infect new trees planted in the same soil.
