What Are These Tiny Black Dots on My Siding? A Guide to Artillery Fungus
Have you ever noticed tiny, black, tar-like specks scattered across your home’s siding? You may have tried to scrub them or even pressure wash them, only to find they won’t budge. If this sounds familiar, you’re likely dealing with artillery fungus, one of the most stubborn and frustrating problems for homeowners in the Tallahassee area.
This guide will explain what this pesky fungus is, why it’s so difficult to remove, and what you can do to protect your home.
What Exactly is Artillery Fungus?
A close-up image of artillery fungus, small black dots on a home’s siding, causing damage.
Artillery fungus (Sphaerobolus) is a wood-decaying fungus that thrives in decomposing organic matter. While its preferred home is traditional wood chip or bark mulch, it is also commonly found growing on rotting boards of wood decks and on decaying tree stumps close to a home.
The name “artillery” is fitting. The fungus grows small, cup-like structures that collect water. As the pressure builds, they launch their spore masses—those sticky black dots—into the air. These spores are phototropic, meaning they are attracted to light or light-colored surfaces, which is why they almost always end up on your home’s bright siding, windows, and trim.
The Challenge: Why Won’t These Black Specks Wash Off?
Unfortunately, those black specks are incredibly durable and act like a super-strong natural glue. In most cases, standard pressure washing or even soft washing will have little to no effect on them.
Removing them typically requires a more aggressive, hands-on approach, such as scraping each individual spore off one by one. However, this method comes with a significant risk of:
Scratching or gouging your siding.
Chipping the paint.
Leaving behind permanent stains on the material underneath.
Often, after the tedious removal process, the affected area needs to be repainted to look uniform again.
Prevention is Your Best Defense
A close-up image of artillery fungus growing in damp, wet mulch at a customer’s home in Tallahassee.
Since removal is so difficult and risky, preventing the fungus from growing in the first place is the most effective strategy. The key is to manage the environment it loves: your mulch beds.
Here are the most effective steps you can take to prevent an infestation:
Choose a Resistant Mulch: Artillery fungus loves wood chips and bark. If you live in a wet climate like ours in North Florida, your best bet is to switch to a less hospitable mulch. Inorganic options like rubber mulch or regional favorites like pine straw are excellent choices that resist fungal growth.
Keep Your Mulch Dry: The fungus needs moisture to thrive. If you use organic mulch, make a habit of raking and stirring it regularly, especially after rain. This helps it dry out faster and disrupts the fungal growth cycle.
Inspect Your Siding Regularly: Periodically check your home’s exterior, especially the areas closest to mulch beds. If you spot the tell-tale black dots, you can act quickly to remove the source.
For a complete breakdown of the best mulch choices and landscaping strategies, you can read our detailed guide here.
If you’ve discovered artillery fungus spores on your siding and in your mulch, it’s crucial to act fast to prevent further spread.
First, carefully remove all the infected mulch. Bag it up and dispose of it in the trash. Do not add it to your compost pile, as the spores are incredibly resilient and can survive the composting process, leading to a new infestation wherever you use the compost.
For the spots on your home, professional assessment is highly recommended before you attempt removal. Our team can evaluate the extent of the problem and recommend the safest course of action to avoid damaging your siding.
Since 2012, Nick Loomis of Hot Water Pressure Washing has been a trusted expert in Tallahassee's exterior cleaning industry. With over a decade of experience, he's passionate about two things: delivering incredible results for his customers and finding innovative solutions to do the job right.
