Artillery Fungus FAQs Asked to Dr. Donald D. Davis, Penn State (Updated Octorber 22, 2008) These are typical, frequently asked questions (FAQ) that I normally field during the spring and summer (very seldom in the winter) -- along with a brief summary of typical answers. Answers are meant to be (hopefully) informative, not very technical, and are not meant to offer concrete solutions. The questions are generally in the order that they are asked. We have these small, black spots that look like specks of tar, all over our white, vinyl siding on our house. It s on the porch, my windows, but it is worse on the siding. It goes all the way up to my second-story windows, and is even under my soffitt and on my gutters. What do you think it is? I think I've seen some spots on my car. Does the artillery fungus also get on cars? Does the artillery fungus hurt pets? So, what exactly is the artillery fungus? I can t see it in the mulch " just how big is the artillery fungus? Is it the same as those little cups called the bird s nest fungus ? Why is it called the artillery fungus? Is it also called the shotgun fungus ? Why do light-colored houses and cars have more problems than darker cars and houses? The artillery fungus problem seems to be much more severe now, than in the good old days. I don t remember this being a problem 20 - 25 years ago. Why is it now a problem? Why is this problem more severe in some years than in others? The number of spots seems to be worse on the north side of my house. Is this just my imagination? Are those spots alive? Will they hurt my house, like eat holes in my siding? So, how do I get the artillery fungus off my house siding? Will any cleaning chemicals remove it? Power washing? How about just plain scraping? Do the spores stick to all kinds of siding? How did the artillery fungus get in my mulch? My neighbors don t have it " only me! Why me! You mean that the artillery fungus can come in on plants and shrubbery that I am planting along my foundation? In your studies, have you found any wood/bark mulches that the artillery fungus absolutely will NOT grow on? So what mulch(es) appear to be best? I have heard that used "mushroom compost" will suppress the artillery fungus. Will it? How about artificially colored mulches? Should I put down new mulch each year? How about composted mulch? Is it better or worse? What if I just paint over the spores on my wood siding? Are there any registered fungicides that will kill the artillery fungus? How about a weak solution of household bleach? I can t get those black spores off my siding, without leaving a lot of small brown stains. My siding is ruined. Will my homeowner s insurance pay for residing my house? I just checked my policy. My homeowner s policy states that it does not cover (that is, there is an exemption) molds . Is the artillery fungus a mold? What is a biological definition of a mold? But the actual spores stuck to the side of my house are not molds, are they? If not, then does my insurance policy include them? Can you recommend a good lawyer who can solve my artillery fungus problem? But, this is America! Who can I sue? Who is responsible? Is the contractor that applied the mulch responsible? Is the person who made the mulch responsible? Is the store that sold me the mulch responsible? So, what is the final, ultimate solution to my problem??? But, I don t like stone - it s so cold! I want to stay organic, and, like, use, like some sort of wood/bark mulch. Yet I can t stand the artillery fungus. It s driving me bonkers. What should I do?? I m at my wit s end. OK, I am going to remove my old, infested mulch. But, what do I do with it? Do you ever get suggestions regarding removal of the spores from surfaces like cars or houses, and have you ever tried any of them? Reader's Suggestions For Removal From Cars Reader's Suggestions For Removal From Houses We have these small, black spots that look like specks of tar, all over our white, vinyl siding on our house. It s on the porch, my windows, but it is worse on the siding. It goes all the way up to my second-story windows, and is even under my soffitt and on my gutters. What do you think it is? Sound like you have the infamous artillery fungus . I think I've seen some spots on my car. Does the artillery fungus also get on cars? Yes, this is common on the sides of automobiles when cars are parked near mulched areas that are infested with the artillery fungus. It is especially noticeable on white sports cars " at least these are the owners that complain the most. In fact, we have had complaints where private companies have artillery spores on 50-100 cars in their parking lots. The next question asked is, How do we remove the spots from the sides of cars? We don't know, but some suggestions have included: power washing if the artillery fungus spots are very new and paint/wax on the cars is also new and shiny; automotive-paint rubbing compounds; and removal (if there are only a few spots) with the edge of a credit card. However, you must be very careful not to damage the car's finish. See some car owners' attempts at removing the spots from cars at the end of this section. These are NOT recommendations!!! Does the artillery fungus hurt pets? Not a problem. So, what exactly is the artillery fungus? The artillery fungus is a white-rotting, wood-decay fungus that likes to live on moist landscape mulch. It is in the genus Sphaerobolus (Greek for sphere thrower ) and is very common across the USA, especially in the East, as well as many other parts of the world. The most common species in Pennsylvania seems to be S. iowensis (contrary to previous reports " including our own). The artillery fungus is technically in the Basidiomycete class of fungi (like the common mushroom that we eat), and probably is most closely related to a group of fungi called earth stars . However, the artillery fungus is much smaller that the earth star that you may see occasionally growing in your yard. I can t see it in the mulch " just how big is the artillery fungus? Is it the same as those little cups called the bird s nest fungus ? The artillery fungus is quite small " the fruiting bodies are about 1/10 of an inch across and are very hard to see in the mulch. They are much smaller than the bird s nest fungus with which they may be confused. By the way, the bird s nest fungus does not actively shoot its spores " those little eggs of the bird s nest fungus are splashed out when a drop of rain hits the cup. Why is it called the artillery fungus? Is it also called the shotgun fungus ? The term artillery refers to the fact that the artillery fungus actively (uses energy) shoots its spore masses, sort of like a cannon or howitzer (an artillery piece). We will call these spores, although they are actually spore masses, or gleba. The spores are usually shot only a short distance, several feet, but the wind can carry them for longer distances and up to the second story of a house. The term shotgun fungus usually refers to Pilobolus, a different kind of fungus that is common on horse dung. Why do light-colored houses and cars have more problems than darker cars and houses? In nature, the artillery fungus shoots its spores towards the light. In the absence of direct sunlight, it shoots the spores at highly reflective surfaces, such as white house siding. And, of course, the black spots show up better on white surfaces, so they are noticed more easily. The artillery fungus problem seems to be much more severe now, than in the good old days. I don t remember this being a problem 20 - 25 years ago. Why is it now a problem? This is a tough question. Wider recognition and awareness of the artillery fungus by the public certainly has led to a perceived increase in the problem. However, I think the problem is also realistically more severe than in past years, partly due to increased use of landscape mulch. There is more mulch being used these days, and therefore, more favorable material for the artillery fungus in our urban and suburban areas. The artillery fungus may be just as common out in flower beds far away from your house, but it is not noticed at that location. But, put the same mulch and the artillery fungus next to your house foundation, add a white or reflective siding, and you may have a severe problem! In addition, the artillery fungus seems to prefer wood as opposed to bark. Much of the mulch that we use today is recycled wood " in the past, most mulch was bark. In addition, the finely-shredded mulches used today probably hold more moisture than the older coarsely ground mulches " this favors fungi, because they need moisture to survive! Why is this problem more severe in some years than in others? The artillery fungus grows better and produces more spores during wet years, such as 2003 and 2004 (here in the Northeast). It is most common during the cool spring and fall, and is much less of a problem in the hot dry periods of mid-summer. The number of spots seems to be worse on the north side of my house. Is this just my imagination? : It is not your imagination, and you are a good observer. The artillery fungus grows better in the mulch on the cool, shady side of the house (usually the north side of the house here in the Northeast) where growing conditions are more suitable for the fungus. Are those spots alive? Will they hurt my house, like eat holes in my siding? Yes, they re alive, but not in the sense that they can hurt your siding. They are dormant, or sleeping, and pose no threat to the siding other than staining it. So, how do I get the artillery fungus off my house siding? Will any cleaning chemicals remove it? Power washing? How about just plain scraping? Do the spores stick to all kinds of siding? The spore masses of the artillery fungus stick like super-glue. We have not found a way to get them off without leaving a stain or damaging the siding, especially on old dry siding. Power washing may work on brand new (only) vinyl siding that still has a shiny, oily, sheen. Each spore mass can be physically scraped, steel-wooled , or sanded off. Then the stain might be removed with an ink eraser, but this is a pain, literally. Beware of any cleansers that have claims that sound too good to be true , with regards to removing the artillery fungus. It is likely that they are, in fact, too good to be true. At the end of this section I have listed some attempts that readers have used to remove artillery fungus. How did the artillery fungus get in my mulch? My neighbors don t have it " only me! Why me! This is extremely difficult to answer. The artillery fungus commonly occurs on dead trees, dead branches, rotting wood, etc. throughout the Northeast. I have seen it in the forest on standing dead trees and limbs on the ground, as well on wood in mulch producing yards. If infested material is used for mulch, the artillery fungus may be already in the mulch when the load of mulch arrives at a job site, and may then grow rapidly along your foundation during cool moist conditions. However, this is likely a problem when mulch is not composted. Or spore masses may already be present at the job site on old mulch, previously infested plant leaves, rabbit or deer dropppings, decaying leaves and grass. These existing spores may immediately infest new applications of mulch. In some cases, the spores also may be transported for very short distances via wind from adjacent infested sources. Spores may also be brought to the site on infested nursery plants, by clinging to the undersurface of leaves, if the nursery also had an artillery fungus problem. When the leaves fall off onto the mulch the attached spores inoculate the mulch here we go again! People can also spread the artillery fungus in various ways. Some homeowners make the mistake of sanding, scraping, or otherwise removing the spore masses from the sides of their houses, and letting them fall onto their foundation mulch. Such spores are dormant, but very much alive, germinate and then infest the mulch. You mean that the artillery fungus can come in on plants and shrubbery that I am planting along my foundation? Yes, this is possible, but only if the nursery had an artillery fungus problem in its pots or beds. But, this does not appear to be very common in my experience. In your studies, have you found any wood/bark mulches that the artillery fungus absolutely will NOT grow on? No. All mulches that we studied eventually supported the artillery fungus after being outside for several years. However, some mulch performed better than others. So what mulch(es) appear to be best? We tested 27 mulches in the field, and found that some supported more artillery fungus than others. In this study, resistant mulch was the large pine bark nuggets. The large bark nuggets stay hard and dry, conditions that the artillery fungus does not like. Cypress mulch also performed well, as it probably contains some anti-fungal, anti-decay chemical(s). I have heard that used "mushroom compost" will suppress the artillery fungus. Will it? Used mushroom compost, also known as "mushroom soil," "spent mushroom substrate (SMS)," and even "black gold" is a great product, if you live in an area where you can get it! Mushroom compost has many beneficial aspects for gardeners, one which is that it supoorts micro-organisms that inhibit many unwanted pest fungi. Mushroom compost is pasteurized before it is used to grow mushrooms, and then is pasteurized after use when it leaves the mushroom house, so it should contain no weed seeds. Our research at Penn State has sown that blending used mushroom compost with a landscape mulch at about 25 - 40 % will greatly suppress artillery fungus sporulation. How about artificially colored mulches? We have tested mulches of various colors, as well as the chemicals themselves used to color the mulches. The chemicals in our tests, at the concentrations used, did not inhibit the artillery fungus. Colored mulches appeared to very slightly, but only temporarily, inhibit the artillery fungus. We attribute this to the colored mulches being slightly more water repellent and therefore remain drier than the non-colored mulches, at least at first. As the colors faded due to rain and sunlight, the artillery fungus moved right in. Should I put down new mulch each year? Interestingly, homeowners that put down new mulch each year generally have less of the artillery fungus problem. But, we have not confirmed this practice. But it does seem to work. Don't miss a year! How about composted mulch? Is it better or worse? You really need to ask this question to a compost expert, but most good mulch today is composted to some degree. However, I would insist on a thoroughly composted mulch. What if I just paint over the spores on my wood siding? That will probably seal them in. It may solve your problem, but will give a pebbly appearance to your paint job. Each repainting will seal in the artillery fungus even more. Are there any registered fungicides that will kill the artillery fungus? How about a weak solution of household bleach? There are no fungicides legally registered (by EPA) against the artillery fungus. Bleach, if it worked, would be very temporary, as it leaches out with each rain. We tested 14 different fungicides in the laboratory, but have to take the experiment to the field. I can t get those black spores off my siding, without leaving a lot of small brown stains. My siding is ruined. Will my homeowner s insurance pay for residing my house? Some insurance companies will and others won t. It depends on your insurance company, your agent, the exemptions in your policy, and especially your lawyer. I just checked my policy. My homeowner s policy states that it does not cover (that is, there is an exemption) molds . Is the artillery fungus a mold? This is another difficult question, and one that lawyers like to argue. Mold is generally thought of as being a superficial, fuzzy fungus growing on damp or decaying organic matter. Like that fuzzy stuff on old moldy bread or on an old orange. The artillery fungus does exhibit such growth during part of its life cycle, when living in damp mulch, and therefore is (at least at times) a mold in part of its life cycle. What is a biological definition of a mold? Biologically, the term "mold" has been used to generally describe a lot of different organisms such as slime molds, sooty mold, pink mold, blue mold on cheese, water molds, etc. These terms may be found in most modern, scientific textbooks or dictionaries dealing with Mycology (the study of fungi). This general biological usage makes the term mold very inclusive; under such a general biological usage, therefore, molds include many types of organisms, such as the artillery fungus, at least during part of its life cycle. But the actual spores stuck to the side of my house are not molds, are they? If not, then does my insurance policy include them? The spores on the side of your house are the reproductive structures of the fungus (although not biologically correct, think seeds ). A good analogy is that they are shot like bullets from a gun. Just as the bullets are not the same as the gun , the spore masses on your house are not the same as a mold . Lawyers can put whatever spin they want on such terminology. And they do. Can you recommend a good lawyer who can solve my artillery fungus problem? No. But, this is America! Who can I sue? Who is responsible? Is the contractor that applied the mulch responsible? Is the person who made the mulch responsible? Is the store that sold me the mulch responsible? Since the artillery fungus can enter the chain of events at various places, I don t see how anyone can be held responsible, unless they willingly supplied mulch with known artillery fungus in it. Which, of course, no good businessman would do! In my opinion, it is nearly impossible to prove where the artillery fungus entered the chain of events. This again is a subject for the lawyers. So, what is the final, ultimate solution to my problem??? Take out all of the infested mulch (usually just around the foundation - not out in the yard), bag it up, and take it to a landfill. Then put down a layer of black plastic, and overlay it with stone or artificial (non-organic) mulch. But, I don t like stone - it s so cold! I want to stay organic, and, like, use, like some sort of wood/bark mulch. Yet I can t stand the artillery fungus. It s driving me bonkers. What should I do?? I m at my wit s end. Well, then, you have to learn to live with the problem. That is, you cannot beat the artillery fungus (at this time) so manage it. Use mulches that the artillery fungus doesn t like, such as large pine bark nuggets. Then, put down a fresh layer of mulch each year " we have no evidence for this, but yearly applications of layers of mulch seem to inhibit the artillery fungus. Another possiblity, but one we haven not investigated, is to use ground cover such as ivy, periwinkle, or pachysandra in place of the mulch around your foundation. It seems likely that the artillery fungus would not grow well under the canopy (on the fallen dead leaves) of such ground-cover plants. Or, establish lawn right up to your foundation. An artifical mulch made of plastic, rubber, etc. should work, but we have not tested it. OK, I am going to remove my old, infested mulch. But, what do I do with it? The best thing to do is probably bag it up and take it to a landfill. At least it s organic and will rot away. Make sure you don t put the infested mulch somewhere where you could be held responsible for someone else s artillery fungus problem. This is out of my field, but it has been suggested that the infested mulch could be put in a yard waste-composting facility. But you really need to ask this question to a compost expert. Do you ever get suggestions regarding removal of the spores from surfaces like cars or houses, and have you ever tried any of them? Yes, I have received suggestions regarding removal of spores from cars or houses. I have not tried any of them. I have listed a few suggestions from readers below, but I emphasize that these have not been tested are not my recommendations. * Note that most involve abrasives, and a lot of "elbow grease", especially if the spots have been on the surface for some time! So, one is really just scraping off the spots, which may land back in the mulch.... Having said that, please let me know if any of these actually do work! Again, these are not my recommendations. Reader's Suggestions For Removal From Cars Corn oil will work to loosen the spores from car finishes. It can be applied using a soft nylon pad, like the "Dobie" Brand (but avoid such pads that will scratch the surface, e.g., Scrunge Pad). Wash it off immediately with soap and hose water after removing the spores. It takes a bit of rubbing, but it will loosen. Do not apply in direct sun as the oil will cook to the surface, especially on hot summer days. Remove the corn oil immediately lest it cake to the car finish. By no means, let it sit overnight. Polish the car thereafter to restore an even finish and remove any residual oil. The spots are on our cars. My husband spent over 2 hours this past weekend picking the spots off of my car. What a mess!! I run an automotive website and have had personal experience with artillery fungus. I did a quick writeup on my blog to let people know what I have done to remove these pesky spores, thought it might be of interest to you. Go to my blog here I have it and my daughter's car was covered in it. I took it to a local detail shop and they used white vinegar to remove it from the car. Car wax worked in the removal from my car (safely) with a little elbow grease. On my new truck, I used 'Turtle Wax Spray Bug & Tar and Tree Sap Remover'. I sprayed it on the spots (in small sections) and let it soak in for a few seconds. I then rubbed the spots with pieces of an old soft towel, occasionally using my finger nail thru the towel. In about 4 hours I got all of the spots off, probably because the spots were 2 days old or less. ... I found the following product to work the best in the area of removing the stain left on a vehicle surface once the sticky portion has been removed: Meguiars-Smooth Surface Clay Kit ...the entire vehicle will need to be done to ensure an even appearance otherwise you'll end up with glossy spots in the treated areas Reader's Suggestions For Removal From Houses I ve used bleach-water on the vinyl siding and it s been the only thing that helped at all (still took some pretty good scrubbing)... Had an estimated 100 plus spots per square foot. A high pressure sprayer, bristle brush, plastic pot scrubber, and strong (vinyl safe) cleaners had no effect on the spots. A sharpened bamboo chop stick was the best tool we found for removing the spots. A sponge and detergent would then clean off the rest. The last thing we had done was to paint over the spores that were on the aluminum trim using oil-based paint and to have a few screens re-screened. Couldn t be removed with a brush and if picked off with a fingernail left a brown stain); called a power washing company, described the situation and they told her it was Artillery Fungus and they wouldn't even take our money because it was I have started using an ink eraser on the spots. It does leave a smudge, but takes out the stain completely. I am going to try car wax to even out the smudges. Labor intensive. I used a sponge with Simple Green on it (full strength is good) and in the other hand you take an INK eraser and you erase it, adding some Simple Green every few strokes. It removes it completely, then you buff the siding hard to remove any eraser smudges. Only way that I have defeated the fungus is to wash the walls with "outside clorox" along with a brillo pad. It is not a sure cure. Had one product that has recently helped me in cleaning off the spots left by the artillery fungus. It's called 'Pro-Tek Chemical' and when mixed in about a 10-1 solution of water ( and while using some small bristled type pad & elbow grease) I have been able to remove much of the worst of it. While I have just started using it, I cannot say what (if any) long term negative outcomes might be on my white siding. Within a week or two after landing, the spores may be emulsified with soapy water or removed with mineral spirits. I have heard that a product called Jomax and bleach may work. I've tried to get the spots off the surfaces and they don't really budge. I am able to remove the "spots" on the windows with a drywall putty knife and some soapy water. We have casement windows, so the fungus that is on the "white" vinyl casement around the window is the worse. Our siding is a wood grain tan color, so it does not show as bad. Here is a solution we recommend for removing the black spots: 1/2 cup detergent (Tide, for example) 2/3 cup trisodium phosphate (Soilax, for example) 1 quart 5% sodium hypochlorite (Chlorox, for example) 3 quarts water We suggest applying this solution with a soft bristled brush and removing with water. Beforehand we tried to remove the black spots with a power washer but to no avail. A year passed by and the condition grew worse. I tried steel-wool, but that really didn't do much. My wife tried a green Brillo pad and water. That had some noticeable affect but seemed to take a lot of scrubbing. Then, I tried Mr. Clean Magic Eraser out on the siding and with very little effort the spots came right off. I tried it on all three sides of the house and it removed every bit of it from the areas I applied the pad. Our vinyl siding has texturing to it, and so it was surprising to see how easy the spots were taken off with the Mr. Clean product. So ecstatic was I that I kept wiping away the spots within arms reach until the pad was depleted. Each spring I take a plastic scraper and remove all the spots I can find, then wash the siding with Clorox Cleanup. It's time consuming and a pain staking process, but I manage to remove 98-99% of the spots, with a thin outer circle usually remaining. When my husband noticed it I went to action right away- the Mr. Clean sponges work really well and I have been able to get the majority of it off of our bay window, screens and door. Of course this is only feasible because it is not as severe as in the past and the rest of the house is brick, but thought you might want to pass this along. It removes the entire spot and doesn't scratch. I have two gardens in the front of the house off the foundation. One side has pure peat moss and the other a wood/bark mulch. Surprisingly, the siding on the peat side has no spotting on the siding! This may be a solution to the problem. Possibly peat inhibits fungus growth.The only downside is cost. From DDDavis: "This is interesting, as many mosses including peat moss specifically are often anti-microbial, even being used in the old days for wound dressings in wartime!? Here is an interesting one: "I am a tenth grade student attending Battlefield High School in Gainesville, Virginia. Through much experimentation in an independent research project I have found the cure to the pestering peridiole problem. Are you interested to learn of my results? I replied, Yes and she sent the following abstract and full report). And, I recently received an email from someone who tried her suggestions, and they said it worked great!!! Just a quick note of thanks for your page on this blight to mankind that has cost me many hours of scrubbing of my cars and siding. Of particular usefulness was the link describing the experiments of the 10th grader in Virginia. Don't know if curiosity got the better of you and you actually tried her recommendations, but if not I can say the kid knows what she's talking about! Following the 2-step process, the spots literally wipe right off. My fingertips and nails are saved! We are having some success with one home with vinyl siding... have been soaking with cleaning solution called power house butyl degreaser and hand brushing, then rinsing. Although there is still a light stain [approx. 75% of the stain is gone], it seems to fade as it dries. We just got vinyl siding on our home...Alcoa's latest. I noticed the black dots this spring [2008] but wasn't surprised as my neighbors have been fighting them on their white vinyl pool fence for years. "Eagle 1 all around [automobile] wheel cleaner" took the dots off of the house siding fairly quickly...with my wheel brush...the cleaner is listed for painted or clear coated wheels. There doesn't seem to be any etching. The dot's have only been there since this spring...We've also used the magic eraser sponges from QVC on the neighbors pool fence but it takes some elbow grease. Live in new condo area. Artillery fungus a very big problem. Believe it or not, used Simple Green, a spray cleaner used for cleaning cars and tools. Tried it on siding. Takes off dark residue and doesn't leave stain. Seems to have no effect on siding. There are hundreds of articles on-line saying you can't get the spots off. But, The kids method works! We did refine it a little by replacing the toothpaste with the Mr. Clean Magic eraser. It's a breeze. We wet a paper towel with mouthwash, wiped down the spots until they softened and wiped off (6-7 swipes did it) and went over the stain with the Magic eraser. The spots were completely gone. Here is another suggestion based on the method suggested by the tenth grader from Virginia: The method works! We did refine it a little by replacing the toothpaste with the Mr. Clean Magic eraser. It's a breeze. We wet a paper towel with mouthwash, wiped down the spots until they softened and wiped off (6-7 swipes did it) and went over the stain with the Magic eraser. The spots were completely gone.