Q: I have this scary looking slime growing all over my yard. What is it and how do I control it?
A: At first glance, I thought this might have been some sort of jelly fungi but after further research and after calling a fellow Extension agent, we discovered it to be blue – green algae called Nostoc commune. This alga is known by other common names such as star jelly or witch’s butter – neither of which really describes how creepy it looks. I felt at any moment something strange would rise up from it – reminiscent of a creature from Ghost Busters!
The strange jelly-like structure can occur during warm temperatures when accompanied by high levels of moisture and/or rainfall. It is also an indicator of compacted soil and/or too much irrigation. It will dry out if the water or rainfall diminishes but it has only gone into dormancy. More than likely it will return if the conditions are right. Star jelly appears in areas where the lawn grass is already weak – however it is important to emphasize the algae does not cause the death of the grass. In fact, star jelly can grow on hardscapes such as driveways and sidewalks.
When applied regularly, some fungicides will help control star jelly but probably not get rid of it permanently. If you decide to use a fungicide, be sure it is labeled for application on lawns and follow the directions on the label. Applying to much of the product, aside from breaking the law, can cause more problems for the lawn grass. The best suggestion in controlling star jelly is to loosen up the soil by aeration and reduce irrigation if watering is contributing to the problem. Another interesting fact – in some Asian cultures, star jelly is eaten although I would not recommend taking it up from your yard and trying it.