Botryosphaeria ribis

Botryosphaeria ribis

File:Botryosphaeria canker.jpg

Botryosphaeria canker on a tree branch

Botryosphaeria ribis is a species of fungus in the family Botryosphaeriaceae. It is known for causing canker diseases in a variety of woody plants. This pathogen is of significant concern in horticulture and forestry due to its ability to infect and damage a wide range of host species.

Description

Botryosphaeria ribis is characterized by its production of pycnidia, which are asexual fruiting bodies that appear as small, black, pimple-like structures on the surface of infected plant tissues. The conidia produced within these pycnidia are hyaline, unicellular, and ellipsoid in shape. The sexual stage of the fungus produces ascospores within asci contained in perithecia.

Host Range

This pathogen has a broad host range, affecting numerous species of trees and shrubs. Some of the most commonly affected hosts include:

• Apple (Malus domestica)
• Grape (Vitis vinifera)
• Eucalyptus
• Maple (Acer spp.)
• Pine (Pinus spp.)

Symptoms

Infected plants typically exhibit symptoms such as:

• Canker formation on stems and branches
• Dieback of shoots and branches
• Leaf chlorosis and premature leaf drop
• Fruit rot in some host species

The cankers are often sunken and may girdle branches, leading to dieback and potentially the death of the plant if the infection is severe.

Disease Cycle

The disease cycle of Botryosphaeria ribis involves both asexual and sexual reproduction. The fungus overwinters in infected plant tissues, and in the spring, conidia are dispersed by rain and wind to new hosts. Infection occurs through wounds or natural openings in the plant. The sexual stage, although less common, can also contribute to the spread of the pathogen.

Management

Management of Botryosphaeria ribis involves a combination of cultural practices and chemical controls:

• Pruning and removal of infected plant material to reduce inoculum sources
• Avoiding wounding of plants, especially during wet conditions
• Application of fungicides to protect susceptible plants, particularly during periods of high risk

Related Pages

• Canker
• Fungal plant pathogens
• Plant disease management