CRAZY-TOP DISORDER OF COTTON 17 
The mature bolls on 20 representative plants were counted in each 
of the 10,000-square-foot areas in one field of Pima where compari- 
sons were being made between the section continuously in cotton 
and that where cotton followed alfalfa. From Table 6 it will be seen 
that the plants in the area where alfalfa preceded the cotton crop 
g) were nearly three times as productive as those on the continuously 
cropped area. The dividing line between the two treatments was 
distinct for the entire width of the field, because of the difference in 
the growth of the plants and in the number of mature bolls. 
Such marked differences between continuous areas as are shown 
in Tables 2 to 6 indicate that the plants under favorable conditions 
either were not susceptible to the factor or agent which caused the 
derangement in the continuously cropped area, or that the effects 
were so masked as to be invisible. If an organic disease is involved, 
it seems clear that the manifestation of the disease is dependent on 
cultural conditions. 
RECOVERY OF DERANGED PLANTS 
That cotton plants affected by crazy-top may recover, at least par- 
tially, under late-season conditions and produce a fair crop of bolls 
in the tops of the plants has been noted by Cook and others who 
have studied the behavior of the disorder. Pima cotton shows more 
recovery than upland varieties, but under certain conditions either 
kind may show a return to normal characters of growth. A field of 
Acala cotton near Peoria, Ariz., showed a high percentage of seri- 
ously affected plants in late August, 1924, but recovery was so com- 
plete by the middle of October that a close inspection of individual 
plants was necessary before the effects of the disease could be 
noticed. 
In July, 1924, four badly dwarfed and distorted Acala plants were 
removed from the center of a badly diseased area near Casa Grande, 
Ariz., by means of date-palm-offshoot transplanters. By the use of 
these transplanters it was found possible to remove individual plants 
with a core of earth about 14 by 18 inches in size and with a greater 
part of the root system undisturbed. These cores were placed in 
galvanized-iron tanks about 2% feet in diameter, and the tanks 
were then filled around the cores with a silty soil of proved produc- 
tive qualities,. The plants were covered with insect-proof cages and 
were watered during the remainder of the season with rain water 
containing a small quantity of sodium nitrate in solution. After 
several weeks three of the plants were discarded on account of an 
infestation of leaf miners (Bucculatrix thurberiella) , but the largest 
plant was retained and by September began to show a return to normal 
growth by producing several vigorous and rapidly growing vegetative 
m branches which developed a healthy growth of leaves, buds, bracts, 
flowers, and bolls. (PL 6, A and B.) At the time of transplanting 
these plants from the affected field, four other plants of equal size 
and similar degree of derangement were selected near the location of 
each of the removed plants (within 5 feet), and these plants were 
tagged for further observation. At the end of the- season all of these 
16 tagged plants were completely sterile and showed no indications of 
recovering. Two untagged plants, located on the edge of one of the 
