132 
MUSHROOMS, HOW TO GROW THEM. 
will cause fogging off to overtake every little mushroom 
that had been attached to these mycelium threads. 
Keeping the bed or part of it continuously wet or dry 
will cause fogging off, so will drip; watering with very 
cold water is also said to cause it, but this I have not 
found to be the case. Unfastening the ground by ab¬ 
ruptly pulling up the large mushrooms will destroy 
many of the small mushrooms and pinheads attached to 
the same clump; and when large mushrooms push up 
through the soil and displace some of the earth, all the 
small mushrooms so displaced will probably waste away, 
as the threads of mycelium to which they were attached 
for support have been severed. A common reason of 
fogging off is caused by cutting off the mushrooms in 
gathering them and leaving the stumps in the ground ; 
in a few days’ time these stumps develop a white fluff 
or flecky substance, which seems to poison every thread 
of mycelium leading to it, and all the mushrooms, pres¬ 
ent and to come, that are attached to this arrested web 
of mycelium are affected by the poison of the decaying 
old mushroom stump, and fogg off. Any impure matter 
in the bed with which the mycelium comes in con¬ 
tact will destroy the spawn and fogg off the young 
mushrooms. Lachaume complains about the larvae of 
two beetles, namely Aphodius fimetcirius and Dermestes 
tessellatus , which “ cause great damage by eating the 
spawn, thereby breaking up the reproductive filaments.” 
Damage of this sort by these or any other insect vermin 
will cause fogging off. But I have not noticed either of 
the above beetles or their larvae about our beds. 
Flock.—This is the worst of all mushroom diseases 
and common wherever mushrooms are grown artificially. 
It is not a new disease; I have known it for twenty-five 
years, and it was as common then as it is now, and prac¬ 
tical gardeners have always called it Flock. I say 
^ worst of all diseases” because I know that mushrooms 
