DISEASES DUE TO FUNGI 97 
consequence commercial growers hesitate to use any 
spray which destroys this “‘ bloom ” or spots the fruit. 
Copper compounds have a tendency to do this, and 
cannot be recommended. 
The foliage of the cucumber is difficult to wet 
thoroughly with ordinary aqueous solutions, and the 
addition of an efficient spreader is necessary. Flour 
paste has proved satisfactory in this respect and is there- 
fore recommended. Liver of sulphur and flour paste or 
lime sulphur and flour paste, the preparation of which 
is described in Chapter IX, have proved satisfactory 
for checking the spread of the disease during the growing 
season. ‘To be quite effective they should be used in the 
early stages of the disease, before the fungus has attacked 
the succulent petiole and stem tissues. Generally one or 
two plants are first attacked, and it is better to sacrifice 
these than to endanger the rest of the plants by allowing 
the diseased individuals to remain untreated. 
When the disease first appears the plants should be 
thoroughly sprayed with either of the mixtures recom- 
mended, and on the next day every “spotted” leaf 
should be cut out and burned. This process of spraying 
and removing the diseased leaves should be repeated 
again at weekly intervals, but generally two applications 
are enough if the fungus has not entered the petioles or 
stems. Spraying should be carried out only in the cool 
of the evening, and the next morning the plants should 
be thoroughly sprayed with water to remove any surplus 
spray liquid that may have remained on them, and 
a little ventilation should be allowed. Care should be 
taken to see that the houses are well shaded, as after 
this treatment direct sunlight may give rise to scorching. 
The effect of the spray on cucumber plants is slight if 
careful attention is given to the above precautions. 
Occasionally the spray burns a newly opened leaf or 
tendril but rarely does any appreciable damage. If 
the fungus is allowed to get a strong hold upon the 
petiole or stem tissues it is increasingly difficult to check 
7 
