COVER STORY
Dancing Elves, Bad Luck and Hexenringe aka
Fairy Rings By Peter H. Dernoeden, Ph.D – Professor Emeritus, University of Maryland
The
cause of fairy rings was the subject of much folklore in Europe in Medieval times. Most agreed that the rings likely were caused by elves dancing in rings, but Germans thought they were burned into the ground by dancing witches (Hexenringe). Entering a ring could result in very bad luck, including loss of an eye or even crumbling into dust; this was especially true on Halloween. Children could avoid trouble after entering a ring, by running around the ring nine times; ten times could put you into much more trouble. More scientifically oriented nineteenth century Americans attributed the rings to the activities of ants or snails or perhaps lightning. Shantz and Piemeisel, excavating fairy rings in Eastern Colorado in 1917, were the first to suggest that fairy rings killed vegetation by rendering infested soil impermeable to water. Even today, the presence of fairy rings conjures interest and mystery, until they start killing your grass (Photo 1). Fairy rings are commonly found in turf and pastures and may be caused by 50 or more species of fungi. Fairy ring fungi belong to a group known as the basidiomycetes or “mushroom fungi,” which includes puffballs. Among the more common mushrooms associated with fairy ring are Agaricus spp, which are closely related to the fresh-white mushrooms you buy in the grocery store. Lycoperdon spp. and Vascellum sp. (known as puffballs) are the primary cause of fairy rings on golf greens. There are many other basidiomycetes commonly found around homes, golf courses, mulched and wooded areas, including bract/polypores (major wood rotter’s); birds nest, club, toothed, earthstars morels, stinkhorns, jelly fungi and artillery fungi. The basidiomycetes play a major role in nature through their ability to degrade organic matter. In particular, they break-down the toughest type of plant organic matter called lignin. Lignin is the strengthening material in cell walls and it occurs in its largest amounts in wood (Photo 2). Most of the fungal body (a network of filaments called mycelium) of a fairy ring resides in thatch and below ground. At some point in time, usually beginning with warmer rainy weather in spring, these fungi produce above ground, spore producing fruiting bodies (i.e., basidiocarps = mushrooms and puffballs). The entire reproductive process remains a mystery
14
MTC TURF NEWS
to this day; specifically, how can a mass of mycelium in soil transform itself to produce elaborate, fleshy above ground reproductive structures? The typical mushroom has a cap and stem. The underside of the mushroom cap is composed of gills, upon which spores are produced. Puffballs do not produce caps and spores are borne within white, fleshy and egg-shaped fruiting bodies. Puffballs often have fleshy warts or spines on their surfaces. Mushrooms and puffballs turn brown as they age, and when they crack or are crushed they release large numbers of spores. Spore color is helpful in identifying basidiomycetes; they can be white, yellow-brown, pink, purple-brown or black. Spores or transport of infested soil spread fairy ring fungi, but it remains a total mystery how a single spore or fragment of mycelium can give rise to perfect green circles or sickle-shaped arcs in turf. Somehow, the fungus initiates growth at a central point (via spores or mycelial fragments) and continues outward in all directions (i.e., radial) at an equal rate (Photos 3, 4, 5, 6). The presence of fairy rings can remain evident all year, especially in lawns. It is not unusual for rings to disappear and then reappear at a later time. They are more notable and numerous in wet years but are most destructive when weather conditions become hot and dry. Fairy rings are among the most destructive turf diseases, but they are not pathogens. Some species do form symbiotic mycorrhizal relationships; this symbiosis is largely associated with trees. Fairy ring fungi cause the formation of rings or arcs of dead or unthrifty turf, or rings or arcs of dark-green, luxuriantly growing grass. Fairy rings are classified into three types according to their effects on turf: Type 1
Those that kill or badly damage plants in rings or arcs.
Type 2
Those that stimulate grass, causing the formation of rings or arcs of dark green turf.
Type 3
Those that do not stimulate grass and cause no damage, but produce fruiting bodies (i.e., mushrooms or puffballs) in rings or arcs.
