116 DISEASES OF GLASSHOUSE PLANTS 
suitable conditions a wound is not necessary for 
infection. 
The rot may be prevented by careful attention to 
the heating and ventilation of the houses, to ensure that _ 
the fruit do not remain covered with moisture for long 
periods. 
Careful pruning of the foliage to expose the fruit to 
the sun and air is also advisable. It is probable that 
sucking and biting insects carry the disease to healthy 
fruits, and these should be eliminated as much as possible. 
A similar disease of the cucumber appears under 
abnormally moist conditions. Infection occurs at the 
flower end of the fruit, and an abundant growth of 
Botrytis develops, which works rapidly over the entire 
fruit. Control measures are the same as for the tomato 
disease. 
Rhizopus Rot of Tomato Fruits.—A soft rot of minor 
importance caused by Rhizopus nigricans Khrenbg. is 
found occasionally towards the end of the season. 
Fruits may be attacked while still on the plant in 
the green condition, and in the first stages of infection 
soft, watery patches resembling bruises are noticeable. 
This rot develops rapidly, the epidermis bursts, and the 
fungus grows out. 
The fungal growth, which appears on the outside of 
the fruit, is very marked in character, showing as a dense 
mass of strong, erect filaments, each of which bears a 
tiny black sphere at the end. These tiny spheres burst 
and liberate numerous spores whereby infection is spread. 
Experiments have shown that the fungus is a wound 
parasite and cannot penetrate the uninjured skin of a 
healthy tomato. Wounds made by insects, or the 
natural splitting of the fruits under unsuitable conditions, 
assist the disease, while warm, moist conditions favour 
its progress. Diseased fruits should be destroyed at 
once, as these become soft and are easily broken, scatter- 
ing infection over the plant. 
