118 DISEASES OF GLASSHOUSE PLANTS 
The malady is most destructive under excessively 
moist conditions, and may be checked by drying the 
atmosphere by means of suitable ventilation. 
Dusting with sulphur powders, accompanied by 
efficient ventilation, will generally effect a control. In 
Fia. 34. Gummosis of the cucumber caused by Cladosporium cucumerinum: (a) Leaf 
lesions, (b) fruit lesions, (ce) hyphx and spores, (d) spores. 
bad cases spraying with liver of sulphur and flour paste 
is recommended, and in any case diseased fruits should 
be removed and burned. 
GENERAL SURFACE DISEASES 
Potato Blight of Tomatoes.—The disease of tomatoes 
caused by Phytophthora infestans (Mont.) De Bary, 
universally known as the cause of the late blight of the 
potato, rarely attacks tomatoes grown in glasshouses 
in this country. It is, however, a common disease of 
outdoor tomatoes, and one may successfully predict its 
appearance if abundant rain falls in July or August. 
Indeed, so serious is this disease in wet seasons that the 
outside tomato crop is frequently ruined, unless regular 
