HYGIENIC CONDITIONS OF GLASSHOUSES 31 
eradicate it once it has gained entrance. Our experience 
in the Lea Valley has shown quite clearly the danger of 
growing plants other than those raised from seed on the 
nursery, and many serious diseases have been introduced 
in this manner. 
(d) Baskets, Sacking, etc.—Another source of infection 
which becomes more and more evident is the contamina- 
tion carried in “ strikes ”’ or baskets, and a considerable 
number of cases have been noted where infection with 
various diseases came from these articles. Such baskets 
may be so mixed at the market that when they are 
returned those from one nursery are sent to another, 
and so disease is spread. Baskets should not be taken 
near to the growing plants for fear of introducing some 
new trouble, and during the winter months all baskets 
should be sterilized in readiness for the coming season. 
(e) Nursery Workers.—Diseases of all kinds are readily 
spread by the workers in the houses. Infection may be 
carried on the hands, clothes, and boots, as well as on 
pruning knives, and therefore assistants working in 
diseased houses should not enter houses where healthy 
plants are growing unless their hands have been washed 
and their clothes either stoved or exposed to direct 
sunlight. The careless visiting of nurseries by workers 
from other places should be prevented, for cases are 
known in which disease was spread in this manner. 
Much of the existing knowledge of crop management 
has arisen from skilled growers as the result of long 
experience, and as most of it is intuitive it is difficult 
to explain to others. Many a grower has learned how 
to produce good, healthy crops on his own sample of 
land and under conditions operative on his own nursery, 
but can give no definite reason for many of his practices. 
It is thus evident that the fundamentals concerned in 
crop management should be exactly determined by careful 
investigation, so that definite reasons for each operation 
may be available, and the grower may be in a position 
