How to Identify and Manage Nostoc in Nurseries and Greenhouses – Part 1

Nostoc, sometimes known as star jelly or witch’s butter, among other names, is a genus of cyanobacteria or blue green algae that can proliferate in almost any environment. It can infiltrate and colonize almost any ecosystem, including polar, tropical, aquatic, terrestrial environments and more.

Colonies of nostoc are made of long filamentous chains, or strands of cells that continue to elongate without separating and can form both microscopic groups under the soil as well as visible mats on a surface (Photo 1). These colony mats can desiccate completely in dry conditions. Dry nostoc can easily be blown around in the wind and spread to undesirable locations. When moisture returns, colonies swell back up into dark green, gelatinous blobs. This form can be introduced to new environments on poorly sanitized tools, shoes and clothes, or by transferring infected plants or growth media between locations. For these reasons, it is incredibly difficult to control the spread and movement of nostoc colonies inside a greenhouse setting.

Habitat Nostoc can be found growing in many different habitats including lawns, garden beds, athletic fields, paved surfaces, container nurseries and greenhouses. They can survive in dry conditions, but for long-term survival they require a wet environment. Hard surfaces like the concrete in a greenhouse or compacted ground of a nursery are perfect environments because the frequent irrigation stands in pools on the poorly drained ground, according to “The continuing battle against nasty Nostoc” by Jennifer Parke. Greenhouses provide perfect conditions for its fast growth and production of biomass due to high humidity, high temperatures and high light levels in addition to frequent irrigation.

Finally, phosphorous is the most limiting nutrient for nostoc, so environments high in phosphorous allow it to thrive, according to the “Nostoc” factsheet by N. Jordan Franklin.

Cellular components As a cyanobacteria, nostoc are photosynthetic single-celled organisms that can live in a multicellular state called a filament. The jelly-like nostoc mats seen in the greenhouse and nursery are made up of these filaments. Living in this state allows the individual cells to share nutrients and cover a large area in search of sunlight, water and nutrients.

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Photo Credit: istockgetty-images-plus-claraveritas