126 DISEASES OF GLASSHOUSE PLANTS 
need no convincing as to the importance of the disease, 
but in the case of the cucumber it is not so obvious. At 
the same time those who cultivate the cucumber must 
have noticed each year that the base of the stem is the 
weak part of the plant towards the end of the season, 
and that given a healthy base there is no reason why the 
plants should not continue to produce fruit for a longer 
period than they do. 
Angular Leaf Spot of the Cucumber 
This disease, due to Pseudomonas lachrymans Sm. 
and Bry. (47), is characterized by brown, angular spots 
on the leaves. These begin as dark, watery spots, and 
examination in the early morning shows the presence of 
a watery bacterial exudate which collects in drops on the 
lower surface of the spots. Later, this watery material 
dries up and leaves a white chalky deposit. The spots, 
which are rarely more than a quarter of an inch in 
diameter, dry up and, becoming brittle, the centre falls 
out, leaving a ragged hole in the leaf. In consequence, 
affected leaves possess a very ragged appearance. The 
disease rarely attacks the fruit, but where it does the outer 
skin is ruptured and an amber gummy exudate comes 
out, which dries up and becomes white. Secondary 
infection by soft rot producing organisms frequently 
occurs and spreads deep into the centre, which in a 
short time becomes soft and watery. This gummosis 
should not be confused with that caused by a fungus, 
Cladosporium cucumerinum, in which the gummy lesions 
become covered with a velvety olive growth. 
Young plants have. been observed to be so badly 
injured by the disease that they have become much 
stunted in growth, and consequently the yield is much 
reduced. In this country the disease is rarely serious 
in normal, well-conducted nurseries, but in America it 
ranks as one of the most important diseases of the 
cucumber. The organism has been shown to enter the 
