What is this in my yard?

Get to know Alabama Extension

(Alabama A&M University and Auburn University) is an equal opportunity educator and employer. Everyone is welcome!

(Alabama A&M University and Auburn University) is an equal opportunity educator and employer. Everyone is welcome!

With all the recent rain, you may have noticed an unsightly addition to your home lawn. It is dark blue-green, has a jelly-like appearance, and is just plain gross! While this organism may look like an alien life form, it is actually a cyanobacterium known as Nostoc.

Nostoc is one of the world’s oldest organisms, colonizing a variety of environments including some of the most inhospitable places that this planet has to offer. There are more than 200 species of Nostoc including both saltwater and freshwater species as well as those that make their home on land.

This organism produces a protective coating that allows it to live under extreme conditions of drought and flooding as well as high and low temperatures. Some species are capable of withstanding freezing and thawing cycles, which allows them to live in both the Arctic and Antarctic.

Finding Nostoc in the home landscape can be alarming. However, the cyanobacteria have likely been there all along as a black shriveled crust just waiting for enough moisture to return to its jelly-like state. Nostoc doesn’t harm lawn or landscape plants. Actually, this organism just takes advantage of the space where grass or other plants will not grow, such as areas with compacted soil, excessive moisture, and high phosphorous levels. It may also form on hard surfaces like wet concrete or gravel sidewalks causing a slipping hazard if not managed.

Now that you know what it is, let’s talk about management strategies. The key is to eliminate as many of the previously mentioned factors as possible.

In turf, aeration is a great way to relieve soil compaction. Also, the addition of organic matter helps to improve soil structure and drainage. Conduct a soil test to determine your phosphorous level. If results indicate high soil quantities, use a fertilizer product containing only nitrogen and potassium as the primary nutrients.

Unfortunately, there are very few adequate chemical controls for Nostoc. While not a long-term fix, products that contain potassium salts of fatty acids, sold as ‘moss and algae killer’ may help on a temporary basis. However, until cultural conditions are improved, Nostoc will return.

Hope this information has been helpful. Happy gardening!

Email questions to Bethany at Bethany@aces.edu or call 205-612-9524. Like us on Facebook. Follow us on Twitter. The Alabama Cooperative Extension System