Slime Mold on Your Lawn: A Comprehensive Guide to Identification, Prevention, and Removal

If you’ve noticed strange, slimy growths popping up on your lawn, you may be dealing with slime mold. While the name sounds disgusting, slime mold is a naturally occurring organism that can be managed with a few simple lawn care practices.

In this comprehensive guide, we’ll cover everything you need to know about slime mold, including:

• What is slime mold and what causes it
• Identifying different types of slime mold
• Is slime mold harmful to your lawn
• Effective ways to get rid of slime mold
• Tips to prevent slime mold growth

Armed with this knowledge, you’ll be able to banish slime mold from your yard and enjoy a lush, healthy lawn again.

What is Slime Mold?

Slime mold, sometimes called grass slime mold or lawn fungus, is a protist, not an actual fungus. The most common varieties appearing on lawns are Fuligo septica (dog vomit slime mold) and Physarum polycephalum (yellow slime mold).

Despite their appearance, slime molds are harmless organisms that feed on decaying matter. They thrive in damp, shady environments with ample sources of rotting leaves, mulch, and dead grass.

Slime molds go through different life stages, each producing characteristic signs on your lawn:

• Plasmodial slime mold: The active, vegetative stage in which the organism moves and feeds. Appears as a network of veins or slimy, web-like growth.
• Aethalium stage: Mature stage in which the feeding plasmodium transforms into a reproductive fruiting body. Looks like a yellowish, mushy mass.
• Sporangia/spore stage: Produces powdery spores that disperse to colonize new areas or await favorable conditions to become active again. Resembles a dusty powder.

Identifying Types of Slime Mold

There are several common slime mold varieties that can grow in lawns:

Fuligo septica: Yellowish “dog vomit” slime mold that can cover large areas of the lawn in a lumpy, mushy mass. When it dries out, it leaves behind a crusty deposit.

Physarum polycephalum: Also called yellow slime mold, it starts as small, yellow dots that merge into an iridescent yellow-gold mat. In dry weather, it forms a powdery mass.

Stemonitis flavogenita: Forms clusters of brown, cigar-shaped sporangia on stalks arising from a slimy plasmodial base.

Didymium iridis: Called the iris slime mold for its rainbow-like fruiting structures. Starts as a wet slimy film but develops into purple-brown sporangia.

Is Slime Mold Harmful to Lawns?

The good news is that slime mold does not infect or harm living plants – it feeds only on decaying matter. So while slime mold looks unpleasant, it will not damage or kill grass blades, roots, or other healthy lawn growth.

However, slime mold thrives in damp, humid, shady areas with lots of decaying debris. These conditions can also encourage fungal diseases like brown patch, Pythium blight, or dollar spot in grass. So a heavy slime mold presence may indicate conditions conducive to turf disease and lawn damage.

How to Get Rid of Slime Mold

While slime mold does not endanger your lawn’s health, you probably want to get rid of it for aesthetic reasons. Here are some effective removal methods:

Manual Removal

For small affected areas, you can simply rake up or hose off the slime mold growth. Rake gently to avoid pulling up grass blades. Follow up with an application of lime or gypsum to raise the pH and make the area less hospitable for future slime mold outbreaks.

Chemical Fungicide Treatment

For more extensive slime mold growth, you may need to apply a chemical fungicide labeled for slime mold control. Always follow the product instructions carefully. Spray onto dry foliage for best results and reapply as directed until the slime mold is gone.

Soap and Water Solution

A mild soap and water mix can help dissolve slime mold masses. Add 1-2 teaspoons of dish soap to 1 quart of water, mix well, and spray onto affected areas. Rinse thoroughly afterwards and allow the grass to dry. Repeat as needed.

Baking Soda and Water Mix

Creating a baking soda solution can help neutralize slime molds. Mix 1 tsp baking soda with 1 quart of water. Add 1/4 tsp of dish soap and shake well until combined. Spray this solution onto slime mold and let sit for 10 minutes before rinsing. Reapply weekly as necessary.

Vinegar Spray

Like baking soda, vinegar can help raise the pH to make conditions less favorable for slime mold recurrence. Mix 1 part white vinegar with 4 parts water and spray onto slime mold growth. Let sit for about an hour before rinsing thoroughly with plain water.

Tips to Prevent Slime Mold

While slime mold can be difficult to prevent completely, you can take proactive steps to reduce conditions that allow it to thrive:

• Water lawn deeply but infrequently. Let soil dry out between watering.
• Thin out trees/shrubs to increase sunlight and air circulation.
• Use a dehumidifier or fan to keep moisture levels lower.
• Apply lime or gypsum to raise soil pH above 6.0.
• Improve drainage and aerate compacted soil.
• Keep grass height 3-4” tall and fertilize to improve health.
• Remove thatch so grass blades can dry quicker after rain or irrigation.
• Eliminate decaying debris by raking often.
• In the fall, mow leaves onto lawn for added nutrition.
• Introduce beneficial fungi that outcompete slime mold.
• Allow grass to dry fully each morning before nightfall.

By diligently managing moisture, shade, debris, and nutrition levels, you can create an environment where lush grass thrives and slime mold struggles to survive. Healthy lawns withstand diseases, weeds, pests, and slime mold outbreaks better.

FAQ:

Here are some common questions people have about slime mold on their grass, along with their answers:

Q: Is slime mold harmful to pets or humans?

A: No, slime mold is not toxic to animals or humans. However, it’s best to keep pets and children away from it to prevent accidental ingestion.

Q: Can slime mold damage my lawn?

A: Slime mold itself does not cause any damage to live grass. However, its presence may indicate underlying issues with lawn health, such as excessive moisture or organic matter.

Q: Can I compost slime mold?

A: Yes, you can add slime mold to your compost pile. It will decompose along with other organic materials and contribute nutrients to your compost.

Q: Will slime mold come back every year?

A: Slime mold can reappear in subsequent years if the conditions are favorable. By implementing preventative measures, you can reduce its likelihood of recurring.