Aspergillus leaf mold

The disease is caused by the fungus Aspergillus fischerianus (synonym Neosartorya fischeri). This pathogen is a type of mold that thrives in environments where plants have been stressed or where the microclimate is poorly managed, specifically regarding airflow and humidity.

The fungus primarily affects ornamental species, with a particular affinity for geraniums, scented-leaf pelargoniums, and ivy-leaf pelargoniums. It can impact these plants at various growth stages, particularly during propagation or in greenhouse conditions where overcrowding is prevalent.

Symptoms of the infection manifest as a visible, fuzzy mold growth on the foliage and stems of the affected plants. As the infection progresses, the tissues become necrotic, lose structural integrity, and eventually rot, which can cause significant damage to the plant's aesthetic and physiological state.

Development and spread of the disease are heavily dependent on environmental conditions, such as high humidity, poor air circulation, and waterlogged soil. The fungal spores are highly mobile and can be spread through air currents, splashing water during irrigation, or contaminated growing media.

Preventive measures are critical for managing this pathogen. Key strategies include maintaining optimal spacing between plants to ensure proper aeration, implementing a balanced irrigation schedule to avoid excessive soil moisture, and using sterilized potting mixtures. If an infection is identified, immediate removal of symptomatic plant parts is necessary to prevent further outbreaks.