Got Black Spots (Artillery Fungus) On Your Siding? Read This For Solutions!

Do you have small black spots on the siding, porch, and even windows of your house? 

These tiny specks may have you pulling your hair out because they are stubborn and just don’t come off.  

Black dots on siding are nasty because they actually boil from the inside out and eventually silently explode. This may sound quite unreal if you’re reading about this for the first time. 

Fortunately, they can’t hurt you as the explosion is merely a big splatter. But it can downgrade your home’s appearance as the gooey stuff inside will splatter all over your house and make a mess that is next to impossible to get off your house.

We know as a homeowner this may not be the only issue on your plate. Every day it’s a new struggle, whether you have to maintain your home, prevent the weed sprouting, or tackle these small black dots on your siding that look like specks of tar sprayed on the surface. 

But before you go on to try every possible remedy available on the internet with no result and a lot of frustration, it’s better if you spend some time learning about this nasty thing – what causes it and how to prevent it. 

So, if you’re up for knowing everything about the tiny black dots on your siding, car, and porch, you’re at the right place. 

Keep reading to know all about the source and removal of these black dots. 

What *exactly* are these blacks dots on the siding? 

First things first, let’s begin with understanding what these black spots/dots are. The black spots on your house are the infamous Artillery Fungus (also know at shotgun fungus)

It’s quite a common occurrence in Iowa and the rest of the eastern U.S. 

Artillery fungus/Sphaerobulus stellatus/Shotgun fungus is a sort of fungus that develops in a moist environment, primarily on rotting wood. But it’s not like any other fungus you may have come across. 

The Artillery Fungus or shotgun fungus you see on your siding is a wood-decaying fungus. It latches onto light-colored outdoor surfaces, whether you have wood, vinyl, or hard-plank siding. 

The black spots are not only limited to cars and siding, but you can sometimes see spots as high as 18 feet off the ground. These are annoying spots, some as tiny as a ballpoint pen and they attach themselves to everything. They are more visible on the light-colored surfaces due to the color contrast.You can see these spots on your cars, gardening equipment, and plants as well.

It’s a fungus that basically loves munching on wood and can become the greatest headache of your life if not dealt with. 

What causes the development of shotgun fungus in the first place?

Source: Wikipedia 

The real culprit for the occurrence of this fungus is mulch. Mulch is one of the idiosyncrasies of the built American landscape. It’s present in almost all of our yards, gardens, parking lots, grocery stores, airports, and highways. People spread a thick layer of mulch everywhere for different reasons.

When you apply hardwood bark mulch to your landscape, it immediately looks sharp and crisp. The mulch also helps to maintain a uniform soil temperature, holds in moisture, and prevents weed growth. But sometimes mulch can lead to an unsuspected problem that many people don’t even realize until it’s too late. It can turn out to be the breeding ground of Artillery/Shotgun fungus. 

A bad batch of mulch that’s already infested with shotgun fungus or using mulch that’s too old without ever flipping allows fungus and other organisms to grow in it. 

Another factor responsible for the growth of shotgun fungus in mulch is the atmosphere. Usually, hardwood shreds or bark chips are used as landscape mulch to hold moisture and add a finished look. However, these wood chips act as a food source for fungi and provide the ideal atmosphere for them to grow and flourish. They break down plant material and utilize organic matter to grow.

Additionally, artillery fungus needs certain weather conditions to grow. Thus, it develops in cool spring and fall weather. The favorable temperature range for artillery fungus is 50 to 70 degrees Fahrenheit. The fruiting bodies of fungus won’t develop in weather above 78 degrees. But it grows rapidly along the foundation during cool, moist conditions. 

What does it look like?


Source: Wikipedia

Shotgun fungus comes in all different kinds of shapes, sizes, and colors. They are all nasty and grisly, but they are different. Since they are a result of wet mulch, warm temperatures, and high humidity, the source may clear away on its own in a relatively short period, but if it has already shot dots upon your siding, those tiny spots are there to stay.  

By appearance, artillery fungus looks like an orange-brown-looking cup that is approximately ¹/10 inch in diameter. The segment of mulch infested with artillery fungi may appear matted and lighter in color than the surrounding mulch, which is safe from infestation.

Artillery fungus is usually found in the non-composted mulch because it does not go through the burning process. 

The burning of mulch (wooden chips) turns it into compost and neutralizes the fungus. Composted mulch eradicates the risk of fungus.

It is also recommended to rake the old mulch and expose the spores to light to dry out the material. Or, add a layer of new mulch over the old to suffocate the spores of artillery fungus.

Why is it so hard to remove?

Shotgun or artillery fungus is, although, from the fungus category but it’s unlike any fungus you may come across. It develops as a mass of fruiting bodies that shoots up spores once it matures. 

It is also known as Sphaerobolus, a common fungus that sticks firmly to light or white-colored surfaces and resembles spots of tar. Its adhesion properties are legendary, and the spots can be difficult, rather, impossible to remove without damaging the surface.

These spores are the black spots you see on your siding. This substance gets so deeply embedded on the surface that it’s nearly impossible to remove. It adheres itself to the surface so quickly, it’s like nothing you could have ever seen before.

Many homeowners or cleaners suggest scraping off the fungus but even if you manage to scrape off the upper layer, it will leave a stain that is untreatable. Mostly, its sticking properties make it utterly difficult to remove. It’s so strong that any or all attempts of removing it ultimately go in vain.

Is it more common on light-colored surfaces than dark? 

Yes, many homeowners have reported that the light-colored surfaces of their house or car had a higher density of black spots as compared to the darker sides. The reason is that this fungus is phototropic, meaning it is attracted to the sun and similar sources. The fungus shoots its spores in the direction of the sun. 

So, it often mistakes the light-colored surface of your siding as the sun and shoots its spores there more than in the other directions. That’s why you’ll see more black dots if you have light-colored siding than your neighbor who has slightly darker siding. 

How does it go from mulch to siding?

It’s natural for one to wonder how a fungus that develops in the mulch gets to the second story of your house. 

Shotgun fungus shoots its spores in the direction of light. But if there’s wind blowing, it can land on the siding of your house and stick to it. The wind and shooting mechanism of shotgun fungus both are responsible for these black spots depositing on your siding. 

It’s even more possible if your fungus-infested mulch is placed close to the foundation of your house as the siding is then close to the fungus. 

Not just siding, but if you have artillery fungus in your garden, you may also find them on the undersides of leaves on plants growing in mulched areas. 

Source: UMaine Cooperative Extension

Is it treatable?

If you ask Google, you’ll get a long list of possible solutions consisting of some legit and some bizarre ways to treat shotgun fungus. While some of these work and some will only waste your time, there’s no denying that shotgun fungus is almost non-treatable. 

You may try every possible solution available on the internet, but chances are that you’ll only be disappointed. 

List of commonly recommended remedies that rarely work.

1. Bleach: It’s the most commonly suggested way of removing artillery fungus. However, it doesn’t usually work. 

2. Peroxide: Second on the list is hydrogen peroxide. Though people claim that it has worked in some cases, it’s highly unlikely. 

3. Mouthwash: It may sound bizarre, but mouthwash is also one of the commonly suggested household items many swear by for cleaning artillery fungus off the vinyl siding. 

Can Power Washing Help in Shotgun Fungus Removal?  

It’s natural to feel that hiring professional power washers for shotgun fungus removal by power washing is the right solution. Unfortunately, power washing or any sort of cleaning techniques don’t work if the shotgun fungus on your siding has matured. 

As professional power washers, we can clean almost anything with our house washing services except for vines and shotgun fungus. It gets embedded so deep it just does not come off. The stains are so stubborn that no amount of cleaning can get them off. 

Take it from us, in our years of experience, there has been no type of power washing technique that could remove the shotgun fungus. 

How to Remove Artillery Fungus Once and For All!

The only solution we recommend for shotgun fungus removal to our clients is the magic eraser. Melamine Foam, better known as the Magic Eraser, is the only solution that effectively works against shotgun fungus. 

It’s truly a magical product to erase the spores that fail the most-advanced cleaning practices. Even if you get the spore off the siding, the stain usually stays behind, but not with Magic Eraser. It successfully removes the stains as well.  

However, be CAREFUL so you don’t take the finish off your vinyl siding!!

The Magic Eraser is a very effective tool, but if you scrub too hard, you can remove the finish from your siding!  So minimize the amount of pressure and scrubbing you use, and test one small area to make sure it looks ok, before you scrub your entire house.  

Cleaning with a magic eraser requires a lot of elbow grease, and you might have to get on a ladder. 

Though we can do this for you, we’d like to point out that it does not require professional expertise. 

So, our advice would be to make it a DIY project as it will be cheaper for you. Also, you can pay the neighbor kid to remove all the spots with a magic eraser. 

We recommend first getting a house wash done via soft washing for best results. 

How to prevent the growth of shotgun fungus? 

There is the possibility of fungi wherever you find decaying wood or mulch. There is no way for you, a mulch supplier, or a landscaper to know if their mulch has this fungus in it. 

The fungus may already be present at the site or could be transported by wind from your neighbor’s house. It can also be on the leaves that blow into your lawn. Another possibility is that it could come from nursery plants that you plant in your flower beds. Artillery fungus is not something that can be easily avoided.

There is no conclusive research about mulches that won’t grow the fungi. However, it has been shown that artillery fungi don’t grow as prevalently in large pine bark nuggets because they don’t get as soft and wet as other mulches.

Since it’s so hard to remove, the best bet against shotgun fungus is to prevent it from growing in the first place. 

  • To save yourself from the nuisance shotgun fungus is, get rid of the mulch around your house and use stones or rubber mulch instead. It’s the only way to steer clear of the infection entirely. 
  • Alternatively, use low-growing plant ground covers as underplantings for foundation shrubs such as liriope, pachysandra, sweet woodruff, and hardy ginger in the shade. 
  • For sunnier spots, use plants like creeping sedum, leadwort, vinca, and liriope. Ensure that you use plants that are deer resistant in your area. Otherwise, you will be creating another headache for yourself.

Additional Tips For Preventing Artillery Fungus

  • Avoid using mulch within 30 feet of light surfaces.
  • Avoid wood chips or pallet mulch.
  • Instead, use rot-resistant mulch like bark, cedar, redwood, or cypress.
  • A better way is to replace mulch with an inorganic ground cover like gravel or stone.
  • Apply a specialty coating to your siding to prevent the growth of shotgun fungus.
  • Since artillery fungus doesn’t grow in a dry environment, stirring up the mulch regularly to keep it dry is another option.

Want to take precautions against shotgun fungus? 

Source: Wikipedia 

Take a walk around your house regularly and ensure that your siding is free from not only artillery fungus but also dirt, algae, mold, and mildew. 

Maintain a safe distance (10-20 feet) between mulch and the foundation of your house to protect it against possible spraying of black spots. 

If you suspect a buildup of contaminants, contact us for professional power washing services and prevent your siding from damage. 


  1. Are all black spots on siding shotgun fungus? 

It’s highly likely that if you have unsightly round black spots on the siding, the reason is shotgun fungus because it is one of the most common causes of such a phenomenon. It is widely known for causing black dots on a light-colored siding. 

  1. How to remove shotgun fungus from vinyl siding?

The solution is singular and the same for all sidings whether you have vinyl or cedar siding. A magic eraser is the only way to remove shotgun fungus from your siding. 

  1. Can surface cleaner help in shotgun fungus removal?

You may come across a few people who claim that surface cleaner or other such solutions work against shotgun fungus, but the truth is that it may be possible in the rarest of rare cases. Otherwise, it never works. 

  1. Should I hire a professional to remove shotgun fungus with a magic eraser? 

Using a magic eraser is more about physical hard work and requires minimal expertise. Though we’ll be happy to do it for you, it’s rather cost-saving to do it yourself or give your neighbor kid a few bucks to do it. 

  1. Can power washing treat artillery fungus? 

Power washing can clean your house of almost everything. It can wash out contaminants from the creases of your siding and windows, but unfortunately, it can’t treat artillery fungus. It’s something that can be prevented or treated by replacing mulch, but power washing alone can’t treat it. 

  1. Can I paint over the black dots on my siding?

Paint will for sure seal the dots, but it won’t solve your problem. Also, painting over the spots will give it a rough & gravelly appearance. As the shotgun fungus will keep shooting the spores, each time, you’ll have to paint it over until you solve the root cause. 

  1. Can a fungicide kill the artillery fungus?

Currently, there are no fungicides in the market that work against the artillery fungus in landscape mulch. 

  1. What is the ultimate solution to shotgun fungus? 

If you want a permanent solution against the shotgun fungus, take out all of the infested mulch and throw it away. Replace it with a layer of landscape cloth or black plastic, and overlay it with stone or non-organic mulch.

  1. How about artificially colored mulches?

If you have artificially colored mulches, it inhibits the artillery fungus a bit less than its counterpart, but as the color fades due to rain/sunlight, the fungus will spare no time in moving on to the mulch and munching on it. 

  1. Can plants and shrubbery from nurseries be the source of artillery fungus?  

It’s possible only if the nursery had an artillery fungus infestation in its pots or beds. Otherwise, you have nothing to worry about, and it’s quite uncommon for nursery plants to have artillery fungus. 

Premier Power Wash

At Premier Power Wash, we understand the struggles of homeowners in Iowa and strive to cross house maintenance off your to-do list through our effective power washing services. We are a team of skilled industry experts who work around your needs and give your property a gleaming polished look. 
So, if you’re looking for professional cleaners to clean your residential or commercial property, book a free on-site consultation with us.

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