Red raspberry slime mold

Tubifera ferruginosa, colloquially known as red raspberry slime mold, is a myxomycete that is often mistaken for a plant disease. Unlike true fungi, this organism is a slime mold that feeds on microorganisms present in decaying organic matter and does not possess parasitic properties against living plant tissues.

The organism is easily recognized by its distinct morphology: during the plasmodial stage, it forms dense clusters of sporangia that resemble small, bright red or pink raspberries. As the organism matures, these clusters change color to a dark, rusty brown, which often causes concern among gardeners who mistake them for rust pathogens.

It typically targets decaying wood, including stumps, fallen logs, and dead branches. The presence of this slime mold is a bio-indicator of compromised wood tissue. It colonizes areas where the wood has already started to decompose due to environmental factors, mechanical injury, or the activity of actual wood-decaying fungi.

High humidity and consistent moisture are the primary environmental conditions required for its propagation. When moisture levels are high, the organism can spread rapidly across the surface of the substrate. While it does not kill the tree, its presence can indicate an underlying issue of wood rot that may require attention.

There are no chemical fungicides recommended for controlling this slime mold because it is not a parasitic fungus. Management strategies should focus entirely on sanitation and physical removal of the host material. By removing decaying stumps and maintaining clean, well-drained garden conditions, you prevent the accumulation of the organic debris that provides a habitat for this organism.