Chorus to “Slip Slidin’ Away” by Paul Simon:
Slip slidin' away
Slip slidin' away
You know the nearer your destination
The more you're slip slidin' away
I’ve posted several Alerts over the years about the ancient cyanobacterium, Nostoc commune (Nc) and always cautioned that the mucilaginous mass can be as slippery as ice. Based on a recent face-to-turf experience, I can say the ice comparison is no exaggeration.
I was focused on looking for bagworms on a spruce and failed to notice Nc creeping within the weakened turfgrass beneath my feet until my feet were no longer in contact with the weakened turfgrass. Thankfully, the only thing hurt was my pride.
Recent rains had re-awaked the sleeping rubbery yellowish-green or bluish-black blobs in parts of southwest Ohio. The ballooning blobs are the hydrated form of this ancient organism. Most of the time, it looks like a black, crusty substance devoid of life.
Nc commonly gets blamed for dastardly deeds far beyond its capabilities such as killing lawns. This cyanobacterium does not kill turfgrass or anything else in Ohio landscapes. Most often poor drainage weakens the turfgrass and Nc fills in the open space by taking advantage of the free available moisture. Indeed, the fate that befell me was directly connected to the opportunistic behavior of Nc as well as a lack of attention on my part.
Older Than the Hills
Nc belongs to a group of cyanobacteria (domain Bacteria, phylum Cyanobacteria) that are capable of producing their own food and releasing oxygen through photosynthesis. Some cyanobacterial have slightly bluish-green photosynthetic pigments in their cytoplasm that are responsible for the misnomer, “blue-green algae.”
There are several evolutionary connections between cyanobacteria and the rise of plants. Biologists generally agree that chloroplasts in plants have their ancestral origins with cyanobacteria through an evolutionary process called symbiogenesis. Without cyanobacteria, higher plants as we know them would not exist, and neither would we.
Cyanobacteria lack membrane-bound nuclei; a condition that makes them a Prokaryote. Plants like algae and animals like you and me are Eukaryotes. We have nuclei that are wrapped in a membrane.
Cyanobacteria have a number of other interesting tricks up their prokaryotic sleeves. They are single-celled organisms that can exist in multicellular states with chains of cells stuck together within a sheath to form a filament. This allows the cells to communicate and share nutrients over a large area which is how many Nostoc species form large, slippery mats.
Nc and others in this genus of unusual organisms are often misidentified because of their changing appearance. During periods of wet weather, Nc may look like an agglomeration of rubbery material "bubbling up" from the soil. Colors range from yellowish-green to bluish-green as Nc hydrates and the cells become active.
The otherworldly appearance of hydrated Nc is responsible for several common names. It was once believed the alien-looking masses originated from the dust of shooting stars (a.k.a. meteors) which accounts for the common names of star-jelly, star-shot, and star-slime. Other common names such as "witch's-butter" are self-explanatory.
During periods of dry weather, the odd-looking masses collapse and turn black. In fact, dehydrated Nc is the form of this cyanobacterium that is most commonly encountered in landscapes, nurseries, and even drainage ditches.
Drying occurs quickly; however, this causes no harm to the cyanobacteria. It's a survival strategy supported by a range of polymers that keep the overall structure intact.
Cyanobacteria have specialized cells called heterocysts that can grab nitrogen out of the atmosphere in a process called nitrogen fixation to convert the nitrogen into molecular forms that make the element available for the bacteria as well as plants.
Some, such as Nc, also have specialized pigments in their cells that absorb UV light to protect against UV radiation. This allows this bacterium to survive intense solar radiation.
In fact, Nostoc spp. has a worldwide distribution and may be found thriving under some of the most extreme environmental conditions. Some biologists consider them to be a type of "extremophile" which is important to remember when you're trying to eliminate them!
Earth has been around for about 4.43 billion years. There was no oxygen in Earth's early atmosphere for the first couple of billion years; it was anaerobic.
That didn't mean life didn't exist, but the life forms that evolved lived without oxygen. Some of those anaerobic microbes still exist, but not where they're exposed to the oxidizing effects of oxygen.
The geologic record shows that something remarkable started happening around 2.45 billion years ago. It’s called the Great Oxidation Event (GOE) and although it happened in a series of stages that “only” took around 400 million years, the ultimate outcome was the Earth’s atmosphere changed from anaerobic to aerobic.
The GOE is marked by bands of rust (iron oxide) in rocks. The rust was deposited after the “free” iron (Fe) met newly liberated oxygen (O). Of course, the marriage was on the rocks from the beginning, literally.
Cyanobacteria, with their capability of pumping out oxygen, arrived on the scene somewhere around 2.45 billion years ago, perhaps a bit earlier. Although there remains some debate as to whether or not these photosynthetic bacteria were entirely responsible for the GOE, it's still generally accepted that these remarkable bacterial oxygen pumps played a significant role in pushing atmospheric oxygen toward the current 21% that we enjoy today. So, you should thank cyanobacteria with your next breath.
Cyanobacteria have been around since before the rise of the Himalayas (40-50 million years ago), the Rocky Mountains (50 – 80 million years ago), and even the Appalachians (500 million - 1.2 billion years ago). They are in fact, older than the hills.
Managing an Ancient
Nc is a remarkable organism that causes no harm and has even been investigated for use in land reclamation sites. However, it and other cyanobacteria in this genus can grow in large mats that present a slippery safety concern in nurseries and greenhouse walkways as well as in weakened turfgrass.
Blackened, dehydrated colonies can create an unsightly mess on the bottoms of plant containers. The same is true with colonies growing in gravel driveways.
Still, it's impossible to entirely eliminate an organism that has survived several mass-murder events from rampaging volcanoes releasing torrents of lava (flood basalts) to a dinosaur-killing meteor strike. However, here are some points to consider when developing management strategies for this most ancient of ancient organisms.
Water: Nc is a terrestrial organism that can survive lengthy periods looking like blackened, dried-out mucus. However, it must have periodical infusions of water to thrive.
So, moisture management through improved drainage is essential. This includes addressing both shallow as well as deep drainage issues. For example, dried Nc mats can clog the drainage holes in weed control fabrics. Using a coarse-bristled push broom to remove dried Nostoc can open the drainage holes. Of course, nothing will be gained if the underlying soil does not drain rapidly.
Fertilizer: Although Nc can generate its own food and grab nitrogen from the atmosphere, it must acquire other nutrients from its environment. In fact, phosphorous is considered the most limiting nutrient in Nostoc development. This has also been observed with the aquatic cyanobacteria that periodically foul lake waters, but don’t call the problem "algal blooms!" So, limiting phosphorous runoff can also reduce the development of terrestrial Nostoc mats.
Chemicals: Algaecides such as sodium carbonate peroxyhydrate and copper sulfate products provide limited to no control of Nc; it's not an alga. Herbicides such as glyphosate not only provide no control (it's not a plant), but the release of phosphorus from dead plants can actually support Nc growth.
Herbicidal soap products based on ammoniated soap of fatty acids or potassium salts of fatty acids provide limited efficacy. However, trials conducted by Oregon State University (the Other OSU!) showed that the most effective herbicidal product is Scythe (pelargonic acid). Not only did Scythe kill Nc but it also prevented regrowth for several weeks and this product is labeled for treatment of algae, moss, or liverworts in container nurseries. Of course, hydrated Nc must be targeted, dried mats are not susceptible. Also, this contact herbicide can damage or kill preferred plants so avoid direct contact as well as drift.
