REFLECTIONS ON DISEASE TREATMENT 185 
special value under glasshouse conditions there is no 
need to discuss them here. 
The Process of Spraying 
Having determined the spray compound best suited 
to control the disease in question care should be exercised 
in its preparation. Only the purest ingredients should 
be obtained, and the method of preparation should be 
carefully studied and followed to the smallest detail. 
Any doubts or difficulties which arise should be discussed 
with an expert who is familiar with the details. Hurried 
carelessness in preparing the spray compound invariably 
leads to disappointing results. 
. Spraying should follow immediately the fungicide is 
ready. The ultimate aim of the process is the covering 
of the entire plant surface with a uniformly thin film of 
the fungicide, and in attempting to spray this should 
be kept constantly in mind. Sufficient liquid must be 
applied to do this, but an excess must be avoided, 
otherwise a deposit of irregular blotches will result. To 
obtain the best results the fungicides should be applied 
to the plants as a very fine mist, and many excellent 
spraying machines have been designed for this purpose ; 
these are fitted with nozzles especially designed for the 
purpose. The amount of pressure used is important, for 
while high pressures assist in the production of a fine mist 
spray, low pressures with the same nozzle produce a 
much coarser spray. 
It is thus apparent that an efficient machine must be 
employed and used correctly if the process is to be » 
successful, All spray fluids must be strained through a 
wire sieve before placing in the machine, otherwise 
clogging of the pipes and nozzles will result, with loss of 
time and patience. Most machines are fitted with 
suitable strainers. It is important to clean thoroughly 
the machine immediately after using, otherwise its 
efficiency will be impaired for the next operation. 
