Dog vomit fungus, also known as dog vomit slime mold or Fuligo septica, is a type of slime mold that can appear in lawns and gardens. The fungus gets its name from its appearance, which looks similar to dog vomit. While unsightly, dog vomit fungus is typically harmless to pets, plants and people. However, treatment may be desired for aesthetic reasons. This article will discuss what dog vomit fungus is, what causes it, and how to get rid of it.
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What is Dog Vomit Fungus?
Dog vomit fungus, or Fuligo septica, is a type of slime mold that is commonly found throughout the world. It is often seen in mulched flowerbeds, lawns, gardens, and on the bark of trees. The fungus gets its name from its appearance, which looks like yellow or tan vomit. It can appear bubble-like or spread out like dog vomit.
Despite its appearance and name, dog vomit fungus is not an actual fungus. Slime molds are protists, which are eukaryotes that cannot be classified as animal, plant, or fungus. There are many different types of slime molds, and Fuligo septica is one of the most common. It is usually seen during times of high heat and humidity.
Dog vomit fungus goes through two main life stages. It starts out microscopic as spores that are spread in the air or by insects. The spores develop into a plasmodium, which is a mass of protoplasm containing many nuclei. The plasmodium oozes around feeding on microorganisms in decaying plant matter. When conditions are right, the plasmodium transforms into the reproductive stage and forms the characteristic dog vomit-like structure.
What Causes Dog Vomit Fungus?
There are a few factors that can contribute to the development of dog vomit fungus in lawns and gardens:
- Excess moisture – The slime mold thrives in wet, humid environments. Excess moisture in the soil or mulch from frequent watering, rain, or poor drainage can encourage growth.
- Mulch – Mulched garden beds provide an ideal environment for dog vomit fungus. The decaying organic material is a food source.
- Wood debris – Rotting wood, such as sticks, logs, or dead tree roots, provide favorable conditions for the organism.
- Poor air circulation – Dense plantings or landscape features that block airflow can allow moisture to accumulate.
- High nitrogen soils – Soils with high nitrogen from fertilizers or organic sources like manure can boost growth.
- Low sunlight – Shady, overcast areas support the development of the slime mold.
- High humidity – Warm, humid climates after periods of rainfall spur development.
While dog vomit fungus prefers moist, shady areas with ample decaying organic matter, it can sometimes grow in nutrient-poor soils and dry conditions as well.
Is Dog Vomit Fungus Harmful?
Dog vomit fungus is not harmful to pets, plants or people. The slime mold feeds on bacteria, fungi, protozoa and organic matter in the soil. It does not take nutrients directly from living plants or animals. Despite its unappealing appearance, it will not cause any diseases.
However, there are a few issues dog vomit fungus can cause:
- It can cover and smother lawn grass, leading to dead patches.
- The growths are unsightly and can develop an unpleasant odor as they decay.
- It can spread to cover wide areas.
- Some people may have an allergic reaction to the spores.
For these reasons, homeowners often wish to remove or control dog vomit fungus in their landscape. The good news is the slime mold usually goes away on its own without treatment. But if you want to get rid of it more quickly, there are some effective treatment options.
How to Get Rid of Dog Vomit Fungus
Dog vomit fungus usually dries up and disappears after a week or two without any intervention. But if you want to speed up the process, here are a few ways to remove it:
Let It Be
Doing nothing is an option if the fungus is in an out of the way area. The plasmodium will eventually transform back into spores and the growth will disappear on its own. This organic approach requires some patience but no effort.
Modify Environmental Conditions
Since moisture encourages the slime mold, take steps to dry out the area:
- Remove excess mulch or debris providing a food source.
- Improve air circulation by thinning out dense plants or obstructive landscape features.
- Increase sunlight by pruning overhanging trees and shrubs.
- Repair irrigation issues causing excessive moisture.
Making the habitat less hospitable will discourage the dog vomit fungus.
Physically Remove It
The slime mold can be manually removed by scooping or scraping it off surfaces. Take precautions to avoid direct skin contact by wearing gloves and avoid inhaling spores by wearing a face mask. Work on a dry, sunny day when the mold is more brittle. Carefully dispose of the collected material in sealed bags with landscape waste.
For lawns, raking or power raking can help remove the growths. Areas of dead grass can be reseeded after removal.
Use a Garden Hose
A forceful stream of water can help blast away the slime mold. This is most effective for cleaning it off solid surfaces like pavement, walls, patio furniture, etc. Try to avoid excessive water runoff into nearby beds or lawns.
Apply Lime
Applying lime to affected areas can help dry out the slime mold. Lime raises the pH, creating a less favorable environment for the fungus. Use an agricultural lime and apply according to package directions. Lime can burn grass if over-applied, so use caution on lawns.
Apply a Fungicide
Fungicide products containing chlorothalonil or myclobutanil can be used to kill dog vomit fungus. Follow label directions carefully:
- Use the fungicide as a spot treatment only on affected areas, not as a broadcast application.
- Make sure the product is approved for use on lawns or gardens if needed.
- Avoid spraying on desired vegetation.
- Wear protective equipment as directed on the label.
- Apply at the recommended rate and frequency.
Chemical control should not be necessary in most cases. Consider other lower impact approaches first before turning to fungicides.
Biological Fungicides
For homeowners wishing to avoid synthetic chemicals, there are also biological fungicides to consider:
- Bacillus subtilis – This bacterium applied as a foliar spray inhibits the slime mold and other fungal diseases. Brands include Serenade Garden Disease Control.
- Chitosan – Derived from crustacean shells, this organic biopesticide can control slime molds and other fungal pathogens.
- Hydrogen peroxide or vinegar – Low concentration solutions (no more than 3% for hydrogen peroxide or 5% for vinegar) can have an inhibiting effect on slime molds.
Follow all label instructions carefully when using biofungicides. Targeted spot treatments are recommended over broad applications.
How to Prevent Dog Vomit Fungus
While dog vomit fungus is unpredictable, you can take some preventive measures to reduce the chances of occurrence:
- Avoid over-mulching landscape beds. Keep mulch 2-3 inches deep, and don’t let it touch plant stems or tree trunks.
- Rake excess organic debris from beds routinely.
- Prune trees and shrubs to increase sunlight and airflow.
- Water early in the day so plants have time to dry out.
- Use drip irrigation or soaker hoses to minimize moisture on foliage and stems.
- Improve drainage in chronically wet areas.
- Turn or remove compost piles frequently.
- Allow lawn thatch layers to dry out completely between waterings.
- Avoid high nitrogen fertilizers which can spur slime mold growth.
With vigilance, cultural practices to eliminate excess moisture and organic matter may keep dog vomit fungus to a minimum. But even with preventive care, slime molds can sometimes occur due to factors out of your control.
When to Call a Professional
In most cases, dog vomit fungus in lawns and gardens can be managed successfully without professional help. However, you may want to enlist a landscape contractor or pest management professional if:
- The slime mold persists and regularly reappears in the same areas despite your treatment efforts.
- It is spreading aggressively across large sections of the landscape.
- You want to identify predisposing factors requiring drainage improvements, grading changes, vegetation removal, etc.
- You do not feel comfortable applying potentially hazardous chemical fungicides.
- The slime mold is impacting high value ornamental plantings.
A professional can assess the scope of the problem and help identify solutions tailored to your unique property’s needs.
Key Points
- Dog vomit fungus (Fuligo septica) is a slime mold, not an actual fungus.
- Excess moisture and decaying organic matter foster growth.
- The slime mold is not harmful, but can be unsightly and spread widely.
- Removal options include physical removal, blasting with water, applying lime, using fungicides, and improving environmental conditions.
- Prevention involves reducing moisture and organic debris.
- Call a professional for help with severe or recurring infestations.
The Bottom Line
Dog vomit fungus is a unique organism that can be alarming when discovered in lawns and gardens. While gross in appearance, it will not harm plants, pets or people. With attention to moisture control and organic cleanup, infestations can often be avoided. If the slime mold does appear, a variety of treatment options are available to remove it. With proper management, dog vomit fungus can be handled without causing long-term problems in the landscape.