98 DISEASES OF GLASSHOUSE PLANTS 
the disease permanently. Its spread may be stopped for 
a time, but as only the spores and spore-bearing hyphze 
on the outside of the plant are killed the hyphe within 
the stem grow out in time and produce masses of spores 
which are rapidly carried about the house and the 
disease again appears. In these cases it is advisable to 
take out the diseased individuals and replant the house 
after thoroughly cleaning it. 
The latter may be done by means of a cresylic acid 
emulsion, after which cleansing planting must be deferred 
for a fortnight; or else by a solution of liver of sulphur 
at the rate of 6 Ibs. in 100 gallons of water, or lime 
sulphur at the rate of 3 pints per 100 gallons. When 
liver of sulphur or lime sulphur is used the house may be 
replanted in twenty-four hours. 
Dusting with sulphur powders has been proved to 
check the disease, but a complete control has not been 
obtained by this means. 
Much can be done to prevent and control the disease 
by providing the best cultural conditions for the plants. 
The disease assumes its worst form, and spreads most 
rapidly, when the atmosphere of the house is badly 
ventilated and saturated with moisture, and also when 
there is a marked difference between the day and night 
temperatures in the houses. The conditions which best 
enable the plants to resist the disease may be summarized 
as follows : . 
Plants should be grown steadily from the beginning, 
without any attempt at forcing, and a little air should 
be given whenever outside conditions will allow. The 
atmosphere of the houses should never be stagnant or 
saturated with moisture for long periods, and efficient 
circulation of air should be encouraged by suitable 
ventilation. The beds should never be cold or sour, and 
careful attention should be paid to the maintenance of 
constant day and night temperature. 
Cladosporiwm Leaf Spot.—Cladosporium cucumerinum 
