Hart's tongue fern rust

Causative agent and type of disease. The disease is caused by the rust fungus Milesina scolopendrii, a member of the Basidiomycetes class. This is a highly specialized pathogen that primarily targets ferns. During its life cycle, the fungus produces various types of spores, allowing it to propagate effectively in greenhouse environments, conservatories, and natural forest habitats.

Host plants. The primary host for this pathogen is Asplenium scolopendrium (Hart's tongue fern). The fungus is specifically adapted to the tissues of the fronds, utilizing them as a nutrient source and a substrate for sporulation throughout the active growing season.

Symptoms and signs of infection. Initial signs appear on the underside of the fronds as small chlorotic spots. As the infection progresses, pustules form in these areas, marking the site of fungal sporulation. These pustules typically exhibit yellow, orange, or reddish-brown colors. Severe infections lead to extensive yellowing, loss of aesthetic quality, and premature senescence of the fronds.

Conditions for development and spread. Milesina scolopendrii thrives in high humidity and moderate temperatures, which are characteristic of greenhouse fern cultivation. Spores are easily disseminated by air currents, splashing water during irrigation, or contaminated tools. Prolonged moisture on the leaf surface is a critical factor that facilitates spore germination and subsequent colonization of healthy tissues.

Prevention and control measures. Effective management centers on strict humidity control and proper air circulation. Overhead irrigation should be avoided to prevent creating an environment suitable for spore dispersal. Upon the first signs of infection, affected fronds must be carefully removed and destroyed. In severe cases, the application of copper-based fungicides or appropriate systemic fungicides labeled for ornamental use can help suppress the disease.