Stinkhorn fungi are a common, unwelcome sight in mulched garden beds, often appearing suddenly after periods of warm, moist weather. This fungus is a saprobe, meaning it feeds on dead or decaying organic matter, which is why it thrives in wood mulch. The primary nuisance is the foul odor it produces, often described as smelling like rotting meat or feces. While the fungus is not harmful to living plants, its repulsive smell makes removal a priority for homeowners seeking control and prevention.
Identifying the Fungus and Its Lifecycle
Stinkhorn fungi, belonging to the family Phallaceae, are recognized by their two-stage life cycle. The organism initially develops underground as a whitish, gelatinous structure called a “witch’s egg,” typically the size of a golf ball. This egg contains the compressed stalk and the spore-bearing cap. When conditions are right, the egg ruptures, and the mature fruiting body emerges rapidly.
The fully emerged fungus is often stalk-like, latticed, or cage-shaped, depending on the species. The offensive odor originates from the gleba, a slimy, olive-brown mass of spores coating the tip of the mature structure. This scent attracts insects, particularly flies, which consume the sticky slime and carry the spores to new locations, facilitating dispersal.
Immediate Physical Removal Methods
The most effective strategy for immediate control involves physically removing the fungi before they release their spores. Targeting the immature “egg” stage is the most productive approach, as this prevents the emergence of the foul-smelling mature form. Put on protective gloves before starting, as the mature fungus leaves an unpleasant residue on skin and clothing.
Use a small shovel or trowel to carefully scoop up the fungus, ensuring you remove the entire base, including the egg sac or the remnants of the volva. It is also advisable to remove the surrounding mulch and topsoil in a radius of approximately six inches to capture any developing eggs or fungal threads (mycelium). This wider excavation helps reduce the chances of immediate regrowth.
The collected material, including the fungus and contaminated mulch, must be properly contained for disposal. Place all materials into a thick, sealable plastic bag or double-bag them in standard garbage bags. Tie the bag securely shut to contain the odor and prevent spore release. The sealed bag should be discarded immediately in the normal household trash; never attempt to compost this material, as doing so will spread the spores.
Addressing the Root Cause: Mulch Management and Prevention
Stinkhorn fungi thrive in environments high in organic matter, warmth, and consistent moisture. The fungus is nourished by the decaying wood in the mulch, which serves as a food source for its underground network of mycelium. Long-term control focuses on altering the conditions of the mulch bed to make it less hospitable to fungal growth.
Improving Aeration and Moisture Control
Begin by improving the aeration of the existing mulch layer, which helps it dry out more quickly and disrupts the fungal network. Periodically turning the mulch with a rake or garden fork, especially after rainfall or irrigation, reduces the moisture trapped beneath the surface. This action can also physically break up the mycelium before it produces new fruiting bodies.
Examine the depth of the mulch layer, as excessive thickness contributes to persistent dampness. Mulch should be kept to a depth of no more than two to three inches; thinning any areas that exceed this limit promotes better air circulation and faster drying. Reducing the frequency of irrigation, or ensuring that water is applied directly to the plants rather than saturating the entire mulch bed, will also lower the overall moisture content.
Replacing Mulch Substrates
For a more permanent solution, consider replacing the current wood-based mulch with a material less conducive to fungal growth. Hardwood chips and shredded bark are primary food sources for stinkhorns and other decay fungi. Removing the old, heavily colonized mulch and replacing it with one of these less desirable substrates can effectively deter future infestations. Alternatives do not provide the necessary organic material for the fungus to flourish:
- Pine straw
- Less woody materials
- Inorganic mulches like pea gravel
- Decorative stone