106 LEE weE. 
are avoided, the disease need not be feared. Particular 
care should be taken to avoid having any water on the 
leaves at night, particularly in dull, cold weather. When 
an attack becomes apparent, the best thing to do is to 
raise the temperature, give plenty of air (but avoid 
draughts), and dry the house off. Galloway speaks of the 
rot as follows, in the article already quoted: ‘‘Wet rot 
of the lower leaves, and rotting, of the stems and conse- 
quent wilting of the plant, are seldom troublesome in this 
[Boston or sandy] soil if properly handled, because the 
surface is at all times comparatively dry. Wet rot is 
produced by a fungus which may be found at any time 
on pieces of sticks and straws scattered through the soil. 
The fungus does not have the power of breaking down 
the uninjured tissues of the plant, excepting possibly in 
very rare cases. When the tissues become water-soaked, 
however, as they do when in contact with wet soil, the 
fungus, which is also most active in the. presence of 
moisture, readily gains entrance and: soon develops suf- 
ficient energy to become an active parasite.’’ 
The mildew (/eronospora gangliformts) is the staple 
lettuce disease of the books, but it is much less frequent 
than the rot. It is induced by sudden changes of tem- 
perature, soft, flabby plants, and too much water at night. 
Fumes of sulphur may be expected to keep it in check 
when the sanitary conditions of the house are set at 
rights. No doubt much of the trouble ascribed to mil- 
dew is really the rot. 
Leaf-burn is a dying of the tips of the leaves when the 
plant is nearly or quite mature. It is particularly trouble- 
some on the heading varieties, in which the slightest 
blemish upon the leaves detracts greatly from the sell- 
ing qualities of the lettuce. This difficulty, according to 
Galloway, is attributable largely to the soil: ‘‘ Top-burn, 
one of the worst troubles of the lettuce grower, does com- 
paratively little injury on this Boston soil, providing the 
proper attention is given to ventilation and the manage-. 
