1900] BOTRYTIS AND SCLEROTINIA ca 
1891 Humphrey (1) described a disease of greenhouse lettuce, 
from which the following is an abstract: 
The trouble ordinarily appears first upon the stem of the plant, about at 
the surface of the soil. Here may be seen at first a soft, dark, decayed spot, 
which rapidly spreads, penetrating the stem and involving next the bases of 
the lower leaves. The latter, being thus cut off from the plant by the decay 
of their bases, usually dry up. With the further progress of the decay the 
center of the head, with the tender inner leaves, becomes attacked, and soon 
collapses into a fetid, slimy mass. In the decaying tissue one can often 
recognize fungus threads, and if they are left undisturbed, there appear on 
the decayed remains the fruiting threads and spores of a fungus; always the 
a The fungus in question.is one-of the imperfect forms known as 
Botrytis or Polvactis,.. .. . In its development, so far as observed, and in 
the details of its structure, this fungus appears to agree with the form known 
as Botrytis (Polyactis) vulgaris Fr.; and is with little doubt the conidial stage 
of some sclerotium-producing Peziza (Sclerotinia). 
Since the above was written the lettuce-forcing industry in the 
vicinity of Boston has largely increased, and forms today one of 
the most important agricultural industries in the state. Diseases 
of the crop have naturally increased proportionally. It is evident 
that the trouble described by Humphrey covers what is now 
generally known in the lettuce district as the ‘‘drop,” and prob- 
ably also more or less of another disease distinguished by the 
gtowers as “black root.” The “drop” is the worst obstacle to 
lettuce growing in the Boston district. Its general nature is 
described in the quotation from Humphrey. Plants growing 
finely and approaching maturity suddenly collapse, the stem at 
the surface of the ground and the bases of the leaves are found 
to be rotted, and in a day or two the plant is completely gone. 
Plants afflicted with the real ‘‘drop’’ never recover. In most of 
these sudden cases, however, no black spot appears on the stem 
as described by Humphrey, nor does any external change in 
appearance take place except that a white, mould-like fungus 
mycelium usually appears and grows vigorously upon the sur- 
Founding soil. This Humphrey does not mention, though it 
seems probable that he would have done so if it had occurred in 
the cases observed by him, as it is very striking. Careful study 
of these diseases show that many cases of “black root” come 
