The Pleated Inkcap (Parasola plicatilis) is common in well-maintained lawns, often appearing suddenly after rain. While these small mushrooms are harmless, their sudden proliferation can be visually disruptive. Achieving long-term elimination requires understanding the fungus’s biology and systematically removing the conditions that allow it to thrive. Addressing the underlying food source and environmental factors is the only way to prevent their recurrent appearance.
Nature of the Pleated Inkcap
The Pleated Inkcap is a saprobic fungus, meaning it sustains itself by decomposing dead organic matter. The organism’s main body is an underground network of thread-like structures called mycelium. This mycelium constantly breaks down materials like dead roots, buried wood, or thick layers of thatch. The visible mushroom, sometimes called the “Little Japanese Umbrella,” is merely the temporary fruiting body of this larger organism.
These fragile structures emerge primarily to release spores, ensuring reproduction and dispersal. Their appearance indicates healthy, nutrient-rich soil containing ample organic material for the fungus to consume. The fruiting bodies are extremely short-lived, often appearing overnight after rain and collapsing within 24 hours as they dry out or self-digest to release spores. Since the mycelium remains hidden below the surface, simply removing the visible mushrooms offers only a fleeting solution.
Quick Fixes for Visible Mushrooms
For an immediate improvement to a lawn’s appearance, the visible fruiting bodies can be removed easily. Physical removal prevents the mushrooms from dropping spores, though spores are also widely dispersed by wind. The simplest method is to pick or rake the mushrooms and place them into a bag for disposal. Avoid adding them to a compost pile, as this promotes further sporulation.
Another effective short-term method is using a lawnmower to chop up the mushrooms, dispersing the caps and stalks into the grass. Alternatively, a strong jet of water can knock down and disintegrate the fragile caps. These actions immediately clear the lawn but do not affect the underground mycelium. The fungus will likely produce new mushrooms quickly if high moisture and abundant food conditions are maintained.
Eliminating the Underlying Food Source
Long-term elimination requires changing the soil environment to make it less hospitable to the Parasola plicatilis mycelium by removing its primary food sources. The first step involves controlling moisture, which is necessary for the fungus to fruit. Reducing the frequency of watering and ensuring the soil has good drainage will dry out the top layers of soil, discouraging the formation of new mushrooms.
A significant food source is thatch, the dense layer of organic matter accumulating between the soil surface and the grass blades. Implementing regular dethatching, or power raking, physically removes this excessive layer. Aerating the lawn by pulling small plugs of soil helps reduce compaction and improves air circulation, speeding up the decomposition of remaining organic debris.
Any buried wood debris, such as old stumps, construction scraps, or large tree roots, provides a substantial, long-lasting meal for the fungus. Identifying and physically removing these items will eliminate a major source of sustenance for the mycelium. If removal is impractical, you can accelerate the natural decomposition of the organic matter using a high-nitrogen fertilizer.
Microorganisms require nitrogen to break down carbon-rich organic materials like wood and thatch, which often have a high carbon-to-nitrogen (C:N) ratio. Applying a nitrogen source stimulates the microbial population, causing them to consume the organic matter more rapidly. This hastens the removal of the fungus’s food supply, reducing the time the fungus has to feed and reproduce, leading to its eventual decline.