Plant Pathology: Extension: Plant Disease Library

Botryosphaeria Canker

Important diseases: Bot canker, Peach Gummosis

Botryosphaeria is an Ascomycete and is the sexual fungal state of several different fungi including Fusicoccum, Sphaeropsis, Botryodiplodia, Dothiorella, and Macrophoma. When looking at infected tissue sometimes Botryosphaeria can be seen, but it is much more common to find one of these fungi associated with the disease rather than Botryosphaeria. Botryosphaeria fungi are weak pathogens that infects wounded or stressed plants. It has an extremely wide host range including fruit trees, vines, and almost every shade tree and woody ornamental.

Symptoms may vary but usually include a sunken or flattened stem canker that eventually girdles the branch or main stem killing all foliage above the canker. In Leyland cypress, infected branches turn a rusty-red color. Canker sites may ooze sap causing the symptom of gummosis.

Spores are produced within sub- epidermal, darkly pigmented, spherical or flattened pycnidia with an ostiole (opening) at the apex through which spores are released. Pycnidia may rupture through epidermis or be produced on a black stroma (compact mass of hyphae). Botryosphaeria fungi are distinguished by the structure of their pycnidia and shape, size, and color of their spores.

Fusicoccum spores are single celled, colorless, and fusoid (spindle-shaped). Sphaeropsis spores are single celled, darkly pigmented (tan to brown), and elliptical. Macrophoma spores are single celled, clear and elliptical.