By Will Summers and Linda Summers, Master Gardeners
The following article is provided offering different views from two Master Gardeners living under the same roof. Two married Master Gardeners may act like gardening detectives similar to the mystery program, the Thin Man movie, and the television husband and wife team of Nick and Nora Charles who have varied views as well as different experience and knowledge.
Her Comments & Views: In our driveway at home, mysterious green algae grow every time it rains. I dislike walking over it because it comes off on my shoes, and I end up tracking pieces of it into the car or the house. As soon as the rain stops, the algae dries up, turns black, and it presents no problem. However, I notice that as soon as it rains again, it becomes like the sponge “sea monkeys” that my children used to play with in the bathtub. It grows and grows, covering dirt, rock and grass. I find myself actually looking for the gravel without any algae to step on as I carefully make my way to the car. The algae are also quite slippery and could possibly cause a fall. In desperation, I asked my husband to get rid of the algae because our gravel driveway is not where I would like to see algae growing. Quite frankly, I don’t look forward to the rain because I know what’s coming!
His Comments & Views: In recent years, we’ve been plagued by a slimy, green gelatinous substance on our graveled driveway. The material disappears each fall and then reappears each summer. I looked at samples under a microscope and saw it as a string of green beads. My guess is that this is just some sort of aggressive algae which is a primitive plantlike material, or perhaps it is even lichen which is half algae/half fungus living together for mutual benefit. I’ve been concerned because this material has spread over a large area, and it causes us to track its remnants into our cars and house. The material dries into a black crust during dry weather only to reemerge each time it rains.
My wife asks me to do something about this (mess) almost every day. However, I find this material growth amazing in its voracity and tenacity. This somewhat plantlike material seems to truly have a life of its own, but it also represents a landscape nuisance and a concern that readers may benefit from knowing. I raked and swept the dry crusty remains without reducing its abundance when favorable conditions return.
Our Findings & Conclusions: Our concerns are over a material scientists call “Nostoc.” Nostoc is the genus given to a large group of life forms classified as “cyanobacteria.” These are neither plants, algae, nor lichens. They are most similar to bacteria colonies. Some bacteria actually produce their own food by photosynthesis and are called “cyanobacteria.” This organism has been previously classed a blue-green algae. Nostoc is not dangerous, and it has been used in medicine. It also has human food potential. Scientists study Nostoc species as a future energy source. Poorly drained soil, a source of nutrients from decomposing organic matter and lawn fertilizers, allow for Nostoc’s rich growth in warm, moist summer days.
There are numerous recommended controls. One control advised not to use is raking, sweeping and removal, which is reported to spread its range. Integrated pest management (IPM) states you should tolerate some infestations. In my wife’s opinion, that is very little. Organic controls recommend applications of baking soda (bicarbonate of soda). This indicates that Nostoc thrives in an acid environment much the same as most mosses. Regular reapplication of crushed limestone gives similar advantage. The Michigan State University Extension website recommends spraying with fungicides on a 14-day interval.
Nostocs are capable of surviving in some of the most inhospitable environments. Nostocs occur from the freezing Artic ice to the boiling hot springs or steaming pools within volcanos. Nostocs survived on early planet Earth billions of years ago before any life emerged on land. Cyanobacteria are attributed to be some of the first living organisms on Earth. Their remains are some of the oldest fossils on Earth.
For more information or lawn concerns, please contact your local University of Illinois Master Gardener or your county Extension office. Please come to the Washington County Master Gardeners Plant Swap at the Nashville Fall Festival on the morning of September 24.
NOSTOC – May Be 3.5 Billion Years Old or Older