Identifying and Managing Mysterious Greenhouse Fungus on Cork and Tree Fern Mounts

A greenhouse enthusiast reached out with a puzzling problem: strange brown blobs appearing on cork and tree fern mounts used for miniature epiphytes. The growth has two distinct stages—one resembling a moist, brown liverwort and another producing a clear jelly-like substance. The gardener hadn't encountered this issue before and wanted identification and eradication advice.

Mysterious fungal growth on epiphyte mounts

Expert Assessment

Dr. Steve Vann examined the photograph but couldn't definitively identify the organism from the image alone. He noted it could be a fungus or even a type of algae, and proper identification would likely require microscopic examination. His primary recommendation was to contact a local county Cooperative Extension office, which can send samples to a diagnostic lab for accurate identification.

Environmental Factors and Management

The expert suspected the growth thrives due to abundant moisture on the inert mounting surfaces. Since the gardener found it on cork, tree fern, and other greenhouse surfaces, the common factor appears to be consistently damp conditions. Dr. Vann suggested that if these surfaces can be allowed to dry out thoroughly between waterings, the organism may disappear on its own.

Practical Steps

• Reduce humidity and improve air circulation in the greenhouse
• Allow mounting materials to dry completely between waterings
• Contact your local Cooperative Extension office for lab diagnosis
• Consider adjusting watering practices for mounted epiphytes

While waiting for lab results, focusing on cultural controls—particularly moisture management—offers the most immediate and environmentally sound approach to managing this mysterious growth.