82 DISEASES OF GLASSHOUSE PLANTS 
disease have yielded satisfactory results. As soon as the 
wilt appears and it is proved that Verticillium albo-atrum 
is the pathogen, the average temperature of the houses 
should be raised above 25° C. by suitably increasing the 
boiler heat, regulating the ventilation, and by closing 
down the houses from two to four hours in the middle of 
the day. A light dressing of whitewash on the glass 
makes the conditions still more favourable for the plants. 
As little water as possible should be given to the roots, 
as heavy watering merely aggravates the wilting, but a 
light overhead damping helps the wilted plants to 
recover. The plants should be encouraged to make 
fresh roots above the original diseased ones by placing 
fresh soil round the base of the plant. 
In one case 68 per cent of the plants in a nursery 
were showing symptoms of wilt disease before the above 
methods were enforced, but a fortnight later only 10 
per cent remained wilted. In view of the fact that low 
spring temperatures are favourable to infection by 
Verticillium, some advantage might be gained by plant- 
ing later than normally, so that the higher summer 
temperatures may arrive by the time the plants have 
reached a stage suitable for infection. 
Examination of the effect of soil type upon the 
incidence of the disease has shown that soils rich in 
humus yield a higher percentage of diseased plants than 
those of a poorer nature. Results obtained on the experi- 
mental plots at the Experimental Station, Cheshunt, 
confirm this, the greatest percentage of Veriecilliwm wilt 
occurring on the plots receiving complete artificials with 
large amounts of dung. 
Soils infected with Verticilliwm may be cleansed by 
sterilization with steam or formaldehyde. 
VERTICILLIUM WILT OF THE CUCUMBER AND MELON 
This disease is in every way similar to that of the 
tomato. The first symptoms are the wilting, yellowing, 
