Dimorphoma

Dimorphoma is a fungal plant disease caused by imperfect fungi of the genus Dimorphoma. This pathogen belongs to the group of micromycetes that primarily infect the tissues of above-ground plant organs. The biology of the pathogen is characterized by distinct dimorphism, which allows the fungus to adapt effectively to changing environmental conditions and survive adverse periods as mycelium or dormant structures on plant debris.

The host range of the pathogen includes mainly ornamental plants and various types of shrubs. The fungus enters plant tissues through natural openings (stomata) or mechanical damage to the epidermis. The progression of the infection disrupts normal plant metabolism, obstructs nutrient and water transport pathways, ultimately leading to systemic chlorosis and tissue necrosis.

Initial symptoms of the infection appear as small chlorotic spots that eventually turn brown or dark gray. In the center of the affected areas, a light-colored bloom consisting of the pathogen's conidiophores is often visible. Without proper treatment, the spots coalesce, causing premature leaf drop and deformation of young shoots, which significantly weakens the plant's overall resistance.

Optimal conditions for the development and spread of the disease include high humidity (over 80%) and moderately warm temperatures ranging from +18 to +24 °C. The infection spreads particularly quickly in dense plantings with poor air circulation, as well as during periods of frequent rainfall and fog. Water droplets facilitate the dispersal of spores (conidia) to healthy tissues of neighboring plants, causing secondary infections throughout the growing season.

Protection and prevention measures involve a combination of agrotechnical practices and the use of chemical controls. Key recommendations for managing Dimorphoma include:

• Prompt sanitary pruning and destruction of infected plant debris.
• Maintaining optimal plant spacing to ensure adequate air circulation.
• Application of preventive broad-spectrum fungicides (such as copper-based compounds or triazoles).
• Managing greenhouse humidity levels and avoiding overhead irrigation.