Artillery Fungus and Bird’s Nest Fungus


A long time ago, one of my colleagues in the Texas A&M Horticulture Department called artillery fungus “small but mighty.” Its tiny black spores (the small part) are nearly impossible to remove from siding, downspouts and gutters (the mighty part). And it’s usually a homeowner’s first hint that this annoyance is popping out from their mulch.

Plants in a landscape bed can be covered with the spores, and the small black spots may also speckle your vehicles. Mother Nature gave these spores the unusual ability to shoot 10-15 feet. (Thus, the name “artillery.”) So, even if there are no nearby plants, it can find its way onto a car parked close to a flower bed or several feet up the siding of a house. It’s most often found on the north side of a residence because it prefers cooler temperatures.

Most artillery fungus is totally avoidable – you just need to use healthy mulch. It’s almost always associated with mulch of the worst quality, especially black dyed mulches, shown with the spoors here.

Artillery fungus is also known as Sphaerobolus, derived from the Greek for “sphere thrower.” (No, not spear-thrower.) And that’s just what it does while decaying and breaking down. It’s become a rising issue in recent weeks because of the very wet and humid conditions we’ve experienced. A mass of this fungus can sometimes seem like a carpet during a Southeast Texas rainy summer.

There’s also a spore known as bird’s nest fungus which can likewise originate in poor-quality mulch. As with the artillery fungus, spores in bird’s nest fungus can burst out and attach to siding, plants and vehicles. They just don’t fly quite as far.

So, how do you control this? First, there is no chemical remedy - no known fungicide will eliminate it completely. The plain and simple solution is removing the poor-quality mulch. If you have this problem, it’s a sure a sign you have the worst mulch around. Instead, use shredded Texas native mulch to make it less likely you’ll suffer from this. Cedar, pine straw and Cypress mulches are also seemingly immune to these fungi. You could also plant groundcovers like Asian jasmine instead of coating an open area with inferior mulch.

And you may be wondering how to remove the spores from your home or car. Well, there is no quick or easy solution. No kitchen-scrubber material is likely to be safe for siding or the paint on your vehicle. My suggestion is to soak the spores with soapy water or Consan 20 and allow it to sit for several minutes, then blast everything away with a pressure washer. If you have any other ideas, I’d love to hear them. So, please give me a call this weekend on the GardenLine radio show.

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PHOTOS: Randy Lemmon, University of Florida Agricultural Extension