CRAZY-TOP DISOBDEB OF COTTON 
13 
It will be observed from the data in Table 2 that in all three of 
the fields the disease was less prevalent in the areas that had been 
cropped to alfalfa. In field No. 1 only three abnormal plants could 
be found in the twenty-eight 100-foot rows in the area following 
alfalfa, and the only derangement in these was the abortion of ter- 
minal buds. (PI. 5, A and B.) In making the plant counts, any plants 
showing aborted terminal buds (except in the very late stages of 
growth) were recorded as diseased plants, although the abortion in 
some cases might have resulted from other causes. It is recognized 
that this procedure is open to criticism from the standpoint of experi- 
mental accuracy, since the abortion of terminal buds is not uncommon 
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Fig. 5.— Diagram of fourteen 25-foot rows of Pima cotton on each side of the division line, field 2, 
between an area cropped to cotton for several years (at right) and another area in cotton the first 
season after alfalfa (at left) . The greater number of affected plants is conspicuous in the area con- 
tinuously in cotton, whereas in the cotton on the old alfalfa land but five plants are shown as 
affected, and the only injuries in these plants consisted of the rather early loss of the terminal buds 
and slight abnormalties of branching such as might follow on a plant which had lost the terminal 
bud by an artificial cause. 0= Normal plant, ©=crazy-top plant 
even in cotton plants which are grown under apparently good field 
conditions; but there appeared to be no other way to account for the 
excessive abortion of terminal buds in' crazy-top fields than to ascribe a 
greater part of it to the same causes which produce crazy-top. Id 
fields 2 and 3 the disorder was much more prevalent in the contin- 
uously cropped areas. Figure 5 shows the position of normal and 
diseased plants in sections of rows on either side of the line separating 
the continuously cropped area from that where cotton followed 
alfalfa in field 2. In field 3 there was a decided difference in the 
