REFLECTIONS ON DISEASE TREATMENT 189 
form of an impalpable powder, for in this state it may be 
easily and thoroughly applied. In this country dusting 
with flowers of sulphur has been practised for many 
years, and recently the so-called “ green sulphur” has 
gained many supporters among glasshouse cultivators 
because of its ease of application. 
Progress along the lines of dusting seems inevitable, 
and should lead to the preparation of a dust possessing 
high fungicidal powers combined with a sufficiently fine 
state to render application very easy. 
In America, dry preparations containing lime, sulphur, 
and various copper salts have been tested extensively 
against liquid fungicides and have compared favourably 
with them. So much is this the case that special mechani- 
cally driven machines able to emit dense clouds of dust 
are employed for dusting on a large scale. In this 
country, however, dusting has barely passed the experi- 
mental stage, but there is little doubt that its importance 
as a factor in disease control will soon be recognized. 
Cleansing, Glasshouses 
Since it has been shown that certain fungi may live 
from season to season in decaying wood, paper, etc., it 
is obvious that very careful cleansing methods must be 
adopted during the winter in any nursery where disease 
has occurred. Fumigation with sulphur has not proved 
entirely satisfactory in every case, and it is advisable 
after vigorous attacks of disease, or in old houses, to 
adopt some method of cleansing the houses with an 
emulsion of cresylic acid and soft soap. Such an emulsion 
is prepared in the following manner: Pale straw-coloured 
cresylic acid 97 to 99 per cent purity and pure potash 
soft soap are placed in a bucket at the rate of 1 gallon 
of the former and 8 lb. of the latter. The bucket 
is then heated over a brisk fire until all the soap is 
completely dissolved, the process taking about ten 
minutes to complete. The strong emulsion is used at 
