Repetophragma biseptatum

Repetophragma biseptatum is a microscopic ascomycetous fungus often associated with the decay of woody plant tissues. It typically acts as a saprotroph or a weak opportunistic pathogen, colonizing parts of trees and shrubs that have been weakened by environmental stress, mechanical damage, or physiological decline.

This pathogen predominantly affects deciduous trees and various ornamental shrubs. In agricultural and horticultural settings, it is frequently identified in nurseries where closely spaced plants or suboptimal microclimatic conditions facilitate the spread of the fungus among weakened specimens that lack sufficient defensive mechanisms.

The symptoms of Repetophragma biseptatum infection include the appearance of distinct, dark, pin-like conidial clusters on the bark surface. As the infection progresses, it can cause tissue necrosis, leading to bark flaking, localized stem cankers, and a general decline in the vitality of the affected branches or stems.

Development and spread of the fungus are heavily influenced by environmental moisture. High relative humidity and frequent rainfall are critical for the production and dispersal of conidia. Wind and splashing water are the primary vectors for transferring spores from infected debris to healthy plant tissues, particularly during moderate temperature cycles.

Integrated plant management remains the best defense against this fungus. Key measures include the regular removal and destruction of infected plant debris to eliminate the inoculum source, ensuring proper plant spacing for improved airflow, and applying protective fungicides on pruning wounds. Maintaining vigorous plant health through balanced fertilization and irrigation is essential to prevent colonization.