CRAZY-TOP DISORDER OF COTTON 6 
RELATION OF STRESS CONDITIONS 
Cook (2) has made reference to the fact that crazy- top symptoms 
are aggravated by stress conditions and that the extent of the injuries 
depends largely upon these conditions, and he has pointed out anal- 
ogies in this respect between crazy-top and other disorders of the 
cotton plant. Several investigators of mosaic diseases noticed the 
effects of different conditions and that under some of these conditions 
the disease symptoms were partially or entirely masked. MacMillan 
(5) has shown that potato mosaic is not evident at high altitudes. 
Walker (11) observed the almost complete masking of symptoms of 
tobacco mosaic in midwinter and attributed this occurrence to the 
growth conditions of the host. Recent studies by Goss and Peltier 
(3) on the degeneration disease of potato show that many of the 
symptoms of the distorted growth were completely hidden in some 
varieties at certain temperatures of air and soil. 
Although the diversity of symptoms and the limited and localized 
distribution of crazy-top are not inconsistent with the possibility of 
an infection transmitted by insects, there are also indications of a 
close analogy between this disorder and certain nonparasitic diseases. 
Since the early observations by Cook, the disease has become more 
widespread, and its occurrence over a wider range of conditions has 
indicated that a relationship exists between the incidence of the 
disease and unfavorable cultural conditions. It is evident from the 
nature of the abnormalities that other factors are involved than those 
which commonly produce stress in cotton plants. Although these 
factors are as yet undetermined, there are indications that they are 
related in some manner to the condition of the soil and to the water 
supply. It is conceivable that peculiar physical conditions may exist 
in certain soil areas in these valleys and that they may produce more 
extreme stress reactions in the plants here than are produced in other 
cotton-growing regions. There is also the possibility of toxic effects 
from some harmful substance that has been absorbed from the soil, 
or of excessive accumulation of such a substance in the tissues. 
Experiments of Erwin F. Smith (10) have demonstrated that the 
local application of purely physical or chemical stimuli may cause 
plant cells to enlarge or proliferate and that injury and death may 
result from their extensive application without the intervention of a 
parasitic organism. Rand (8) has pointed out that metabolic 
and structual changes occur in the environmental type of plant 
derangement. 
A lack of sufficient water or soil nutrients may result in a modifi- 
cation of cell structure, with a tendency to reduce transpiration and 
to dwarf and harden the tissues. The establishment of proof in recent 
years of the causal relationship of infective viruses with many of the 
common plant disorders that were long considered of environmental 
origin makes it desirable to give careful consideration to the possi- 
bility of this type of disease being involved. 
A disease which shows parallels with crazy-top in its relationship 
to cultural conditions and in some of its symptoms is pecan rosette, 
which Orton and Rand (7) and McMurran (6) have classed as non- 
infectious and noninheritable. McMurran, in describing the condi- 
tions under which it is commonly found, states that "rosette is found 
on soils which are for some reason ill suited to conserve moisture or 
