86 DISEASES OF GLASSHOUSE PLANTS 
which enable the fungus to exist through unfavourable 
conditions. 
Fusarium lycopersici is able to live as a saprophyte 
in the soil, and while it is known to have remained there 
for three or four years in the absence of a tomato crop, 
there is no reliable data as to limit of its saprophytic 
existence. It has long been known that heavy dressings 
of caustic lime tend to produce a considerable reduction 
in Fusarium wilt. 
Temperature Relations.—Inoculation experiments con- 
ducted under different temperature conditions have 
demonstrated that temperature is a limiting factor in this 
disease, just as it is in the case of Verticilliwm wilt. | 
Infection is most successful, and the disease develops 
most rapidly at a soil temperature of 29° C., while little 
infection occurs if the temperature remains constantly 
much below this. 
Control of the Disease-—In a climate like ours, which 
is unfavourable to the disease, it may be controlled by 
reducing the temperature of the soil and the air, but in 
favourable climates control is dependent upon efficient 
soil sterilization by heat or formaldehyde or the raising 
of resistant varieties of tomato plants. 
FUSARIUM WILT OF THE CUCUMBER AND MELON 
The temperatures of the soil and atmosphere in which 
these plants are cultivated are more favourable to Fusarium 
wilt than those of a tomato house. In consequence this 
disease is not uncommon in this country. 
The symptoms are much the same as in the previously 
described wilts. In slight cases of the disease, when the 
plant possesses high resistance, the symptoms may be 
that of stunted growth and a reluctance “to break” on 
the part of the laterals; but as these symptoms can be 
due to unsuitable physical conditions of the bed, this 
stage of the disease may frequently be overlooked. 
Later, the lowest leaves become affected and soon the 
