ACROMANIA, OR “CRAZY-TOP,” A GROWTH DISORDER 
OF COTTON 1 
By O. F. Cook 
Bionomist in Charge , Office of Acclimatization and Adaptation Investigations , 
Bureau of Plant Industry , United States Department of Agriculture 
THE NATURE OF GROWTH DISORDERS 
Some of the diseases of cotton are manifested by abnormal growth of the plants, 
without localized injuries like those associated with parasitic fungi or bacteria. 
A remarkable feature of growth disorders is that the plant characters and habits 
of growth may be changed suddenly, the normal characters being replaced by 
abnormalities of many kinds and degrees. The changes of characters often are 
so complete that the abnormal growth would not be recognized as belonging to 
the same variety as the early growth of the same plant, or even to the same 
species, if the connection were not known. To appreciate the extent of the 
abnormalities, it is necessary to be familiar with the normal characters and de¬ 
velopment of the plants, as in the study of breeding and adaptation of varieties. 
Similar disorders affect other plants, and some of them are known as mosaic 
diseases, because the leaves are discolored in irregular patchwork areas of light 
and dark green. But in crazy-top the growth is abnormal in other ways, with¬ 
out discoloration of the leaves. Some of the disorders are temporary, with a 
later return to normal growth, while other disorders are permanent so that the 
abnormalities continue to appear in all of the new growth that takes place. 
When the changes of characters are permanent the growth disorders appear 
somewhat analogous to “bud mutations. ,, 
Since the symptoms of crazy-top are aggravated by stress conditions, it might 
be expected that the cause would be found in some peculiarity of the environ¬ 
ment. The presence of harmful substances in the soil is easy to assume and 
difficult to disprove, but with crazy-top there is no indication that any par¬ 
ticular type or condition of soil is associated. The disease occurs under a wide 
range of cultural conditions, and appears sporadically in scattered individuals, 
as well as in more compact groups of plants, or in large areas. The mode of 
occurrence of crazy-top is consistent with the possibility of an infection dis¬ 
tributed by insects. It is known that several of the mosaic diseases of other 
plants are carried by insects, and that some of the diseases are very infectious, 
so that only slight surface contacts are necessary to spread the “virus. ” 
The underlying cause of mosaic diseases is still obscure, even with those that 
have been studied most carefully, as in sugar-cane, sugar-beets, tobacco, and 
potatoes. Some pathologists credit the idea of very minute Protozoa, smaller 
than bacteria, beyond the limit of microscopic vision, as indicated by the passage 
of contagious “virus” of mosaic disorders through filters that are impermeable 
to bacteria. Other investigators have sought for causes of such diseases in 
organic poisons, or in the reactions of organic ferments or “enzymes.” The 
causes, no doubt, are different for the disorders that are not permanent nor 
infectious, though one of the temporary disorders of cotton is due to plant lice. 
Another may be a physical injury or traumatism, primarily affecting the oil- 
1 Received for publication May 1, 1924. 
Journal of Agricultural Research, Vol. XXVIII, No. 8 
Washington, D. C. May 24, 1924 
Key No. G-432 
96038—24t-7 
(803) 
