Recently I’ve received questions about a strange, slimy mess appearing in people’s lawns, leading to concerns about what it is.

This gelatinous mass is called nostoc, a type of cyanobacterium that is one of the oldest known life forms on Earth. It has survived in harsh environments, from the deserts of Australia to the Arctic and has likely existed for around 3.5 billion years, making it quite resilient and difficult to eradicate.

Nostoc colonies consist of chains of bacteria that can be found on the surface of soil, cement, rocks or even floating on water. When it absorbs rainfall, it swells into a slimy, green-brown jelly-like mass, which can range in size from microscopic to that of a walnut.

The key to its survival lies in a brown jelly coating that protects the bacteria from drought and ice, as well as its ability to fix atmospheric nitrogen. Nostoc reproduces through fragmentation and can remain viable for up to 70 years in dry conditions. Upon receiving water, it germinates into filamentous structures, and the life cycle begins anew.

While nostoc may look threatening, it is harmless to both plants and animals. Although it may not be visually appealing in a lawn, it will not harm the grass. The presence of nostoc often indicates drainage issues, overwatering or soil compaction. It tends to thrive in thin, patchy lawns where water accumulates on the surface.

To control nostoc, it is best to improve drainage by coring or verti-mowing, and to reduce watering and the use of phosphorus-based fertilisers. Lawns situated in clay soil are more prone to nostoc than those in sandy coastal areas.

In late spring or summer, nostoc will dry out and become crusty. This is the ideal time to scrape it off with a spade and aerate the lawn.

Another method of control involves spraying pelargonic acid (commonly known as Slasher) in mid-spring, then withholding water for two weeks after spraying. Pelargonic acid is also effective for managing algae, moss and liverworts.

Tip of the week

Federation daisies and Euryops are great options for adding colour to winter gardens. They require minimal care and bloom for many months, thriving solely on rainfall without the need for additional watering.

Three jobs to do now

1. Hydrangeas can be pruned down to the fattest buds but if you live in frost prone areas, leave pruning until the end of this month.

2. Visit nurseries to check out the range of banksias and hakeas, many of which flower in winter.

3. Either hand weed or mow lawns to prevent winter weeds from seeding. It’s best to get on top of them now rather than deal with a mass of weeds later.

Do you have a question for Sabrina?

To submit a question to Green With Envy, inside Saturday’s The West Australian, write to Ask Sabrina, GPO Box D162, Perth, 6001 or email home@wanews.com.au. Please include your full name and suburb. Due to the volume of questions, not all of them will be answered.