166 COTTON 
ingly, or grown under some plan involving a con- 
stant change of crops in which cotton appears only 
once in four or five years, there would be consider- 
ably less trouble from disease; for it is only in those 
cases where a disease gains a foothold that it causes 
appreciable loss to the cotton farm, and to gain 
such a foothold permanently cotton must be 
grown on the same land in fairly quick succession. 
The same principle of disease as it applies to the 
cotton plant, or in fact to any plant, applies also 
in animal life. Texas fever, for instance, affects 
cattle only where they graze upon the same land 
year after year and thus give the tick time to put 
a new generation through the full cycle of changes 
each season. But if, on the other hand, cattle are 
withdrawn from the affected territory, and kept 
from it a year or two, the tick disappears as soon as 
the process involved in the completion of its life- 
history is disturbed, and it perishes, leaving the land 
entirely free from that time on. Perhaps there 
would be no eradication of the disease were the 
lands continually grazed without any period of 
intermission. 
It is so with our cotton diseases where the crop 
is grown continually, as cotton usually is. ‘There 
is no disturbance of the life process involved in the 
disease and so it comes on year after year, com- 
pleting its full cycle of development. 
The treatment of disease in general then should 
involve preventive methods rather than specific; a 
wise system of farming that will improve the land 
and make it stronger—this will mean interference 
in the development of the disease; this will lessen 
its ability to do harm, until it perishes altogether 
for want of necessary surroundings and satisfac- 
tory environments. 
