238 
Journal of Agricultural Research 
Vol. XI, No. S 
total loss of the crop over the areas occupied by the ring. In some 
areas these rings are very numerous. It is estimated that they influence 
between 0.5 to 1 per cent of the area shown in the map (fig. 1). Even a 
1 per cent reduction in gross yield is important when deducted from the 
net profit. Although there are areas where no fairy rings occur, other 
areas are badly infested with them. Often areas are found where the 
rings are more abundant than shown on the map. 
In experimental plots the presence of fairy rings is a serious obstacle. 
A large ring of Agaricus tabularis may reduce the yield of a one-tenth 
acre plot to 50 per cent. Under a most favorable set of climatic con¬ 
ditions it may greatly increase the yield. It is therefore impossible to 
rely on results from plots occupied by fairy rings. Many of the inequali¬ 
ties of experimental plots are due to this cause, and the eradication of 
rings on such plots is as important as the experiments which are conducted 
on the plots. 
Persoon (1819, p. 4) observed that if a ring was dug up successively 
for one or two years the same species reappeared eventually, but it was 
solitary and scattered. 
Sorauer (1886 p. 270-272) stated that repeated digging up of the soil 
at the periphery of the ring would dry and kill the fungus. 
McAlpine (1898) recommended soaking the ground thoroughly with 
sulphate of copper (or Bordeaux mixture), sulphate of iron 10 per cent, 
and strong lime water to kill the fungus. 
Ritzema Bos (1901) stated that the rings could be destroyed by digging 
them up in dry, hot weather and exposing the soil to sunshine. 
The principal methods suggested for the destruction of fairy rings 
have been the application of sulphates of copper and iron or repeated 
stirring of the soil, especially during dry periods. The latter method 
would be best when applied to experimental plots, since it would not 
introduce into the soil chemical substances which might possibly have a 
subsequent effect on crop production. Where the method of digging 
up the soil is not practicable, the application of fungicides, such as 
Bordeaux mixture, to the soil immediately over and a little in advance 
of the rings should be effective. 
SUCCESSIONS INDUCED BY FAIRY RINGS 
None of the previous investigators made a study of the revegetation 
following the destruction of the vegetation in the fairy ring. Tulasne 
and Tulasne (1851, p. 157) mentioned the fact that the production of 
weeds is due to the digging up of the soil by truffle hunters. Ballion 
(1906) noted the fact that at the first rains in the fall the perennials on 
the denuded zone, like “ravenelles” (wallflower) and “oseille” (sorrel), 
began to grow again and annuals sprang up from seeds fallen on the bare 
ground. None of the other investigators mentioned the effect on 
revegetation. 
