8 BULLETIN 1484, U. S. DEPARTMENT OF AGRICULTURE 
SLOPE OF LAND AND DISTRIBUTION OF SOIL MOISTURE 
During the survey of the disease which was made in November, 
1925, much evidence was obtained which indicated that the disease 
symptoms were influenced by the water supply in the soil. Several 
fields were observed where the only large areas of plants which were 
not seriously deranged were narrow strips at the lower end of the 
borders, where water was impounded and had sufficient time to enter 
the soil. (Fig. 3.) 
In most cases these fields had a steep slope as well as a somewhat 
impervious topsoil, and it was evident that the irrigations applied 
after cultivations were discontinued penetrated only a few inches, 
except near the head ditches and at the lower end of the borders. 
An example of this sort is seen in Plate 2, where the normal pro- 
ductive plants at the lower end of the field contrast strikingly with 
the diseased plants at the upper end; the latter produced relatively 
few bolls, of which a large proportion were abnormal in some 
respect. 
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Fig. 3. — Diagram showing effect of water penetration on severity of crazy-top disorder at the lower 
end of a field which had a grade of about 40 feet to the mile. The diagram represents a typical 
section twelve 100-foot rows. It will be ' noted that there are only a few diseased plants in the 
lower 50 feet near the waste ditch. The dividing line was distinct for the quarter-mile width of 
the field. 0=Normal plant, ©=crazy-top plant. The right-hand part of the diagram repre- 
sents the lower end of the field 
It was also characteristic of these fields with steep slope that the 
outside rows either were free of the disease or showed only mild 
symptoms late in the season, and the plants were conspicuously more 
productive than those inside the field, indicating the advantages 
which these plants undoubtedly had in obtaining moisture. Plate 2, 
A, shows an outer row of Acala cotton in such a field, with all plants 
productive, although some of them manifested the disease late in the 
season, while the other plants remained normal. It will also be seen 
that the second row in this field had fewer bolls owing to the fact 
that the disease affected the plants earlier and more severely. The 
plants in the third, fourth, and ensuing rows were still more severely 
affected and produced no bolls of normal size. Another example, 
from the same field, of the complete sterility and abnormality of the 
plants of the inner rows, in contrast with normal well-fruited plants 
in the outside row, is illustrated in Plate 2, B. The number of nor- 
mal and diseased plants in several of the outer rows in 50-foot sections 
from each side of this field is graphically shown in Figure 4. In the 
outer rows many of the plants shown as affected by crazy-top pro- 
