Nostoc is a cyanobacterium and is one of the oldest organisms on earth (over 3.5 billion years). It is a primitive growth, like algae, moss, and liverwort. Many years ago, it was incorrectly identified as blue-green algae. Nostoc has no roots, no vascular tissues & is not a plant but it is photosynthetic. It can be found growing within gravel, stones, limestone chips, granite, saturated soils & on-ground cloth within container nurseries. It can tolerate long periods of desiccation but requires plentiful amounts of water for establishment. This cyanobacterium growth can become common & persistent at certain nursery/greenhouse sites where long-term overhead irrigation is done.
Nostoc growing in front of container bay opening. The opening allowed the overhead irrigation to saturate the soil/gravel at entrance. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)
Nostoc growing on ground cloth within a nursery container bay. Creates a serious slipping hazard for nursery personnel. (Photo Credit: Steven K. Rettke, Rutgers Coop. Ext.)
Nostoc is not toxic & does not directly compete with nursery/greenhouse crops or landscape plants, but it can harbor fungus gnats & snails. Nostoc first became a growing concern in nurseries approximately 30 years ago. Slipping hazards are the primary threat this organism poses to nursery & greenhouse personnel. It forms gelatinous masses composed of filaments linked together by protective jelly-like coverings. This creates a surface as slick as wet ice. Nostoc can occasionally be found growing within turf or landscape settings but is not common.
This blog will show with photographic images how Nostoc can be identified & will also review available control options.
