A DISORDER OF COTTON PLANTS 
IN CHINA: CLUB-LEAF OR CYRTOSIS 
A Serious Limiting Factor of Production Not Hitherto Recognized, 
Resulting in Abnormal growth and Sterility 
O. F. Coox 
Bureau of Plant Industry, U.S. Department of Agriculture 
HY China does not produce 
\ \ / more cotton is a question to be 
answered largely in terms of 
disease and insect injury. The 
total production undoubtedly could be 
increased greatly, and the quality im- 
proved, if selection and other precau- 
tions were applied, but the pests and 
diseases are not to be disregarded. In 
addition to direct damage by the pink 
boll-worm and other insects, there is a 
peculiar abnormality or disordered be- 
havior of the plants, which undoubtedly 
is one of the principal limiting factors 
of cotton production in the central 
regions of the Yangtze Valley. Though 
not showing definitely diseased spots or 
other localized injuries that bacteria, 
fungi or insect parasites usually inflict, 
the plants are crippled, the leaves re- 
duced in size, discolored and distorted, 
the petioles and internodes shortened, 
and the branching habits changed. 
Badly affected plants become somewhat 
club-shaped, with a dense “witches’- 
broom” growth of dwarf branches and 
small crumpled leaves at the top, which 
has suggested “‘club-leaf” as a name for 
the disorder. 
OTHER NON-PARASITIC DISORDERS 
The word disorder has been applied 
to other forms of abnormal behavior of 
cotton plants in the United States, such 
as the leaf-cut or tomosis, which also 
occurs in China and often is associated 
with severe cases of club-leaf. The 
effect of tomosis is to kill irregular 
areas of leaf-tissue, giving a ragged 
*A leaf-curl disease of cotton in East Africa has been ascribed to “cicaden.” 
1911, Beitraege zur Kenntnis der Kraeusel-Krankheit der Baumwolle, Der 
For descriptions of leaf-cut and leaf-curl see Circular 120, Bureau of 
Kraenzlin, G., 
Pflanzer, 7 :327. 
appearance that may be mistaken for 
insect injury. The damage begins with 
dead oil-glands and spreads to the neigh- 
boring cells, sometimes destroying large 
portions of young leaves, which may 
regenerate partly to form even rounded 
margins, but in very abnormal shapes 
(see Fig. 4). 
Club-leaf shows a closer analogy, as 
well as more resemblance to the leaf- 
curl disorder caused by plant-lice. With 
both disorders the leaves are distorted, 
but in leaf-curl the base of the leaf 
is deeply crumpled, while in club-leaf 
the margins and lobes are more af- 
fected, rather than the base of the 
leaf. (Compare Fig. 3 with Fig. 4.) 
Leaf-curl affects the seedlings, is most 
prevalent in the spring months, and 
usually causes only slight and tempo- 
rary injury, whereas the Chinese dis- 
order does not come in the spring but 
is most injurious during hot weather, 
at the height of the fruiting season. 
Though such disorders may not be 
directly transmitted they need to be 
studied from the standpoint of heredity. 
The different kinds of cotton show 
various reactions and degrees of sus- 
ceptibility or immunity, which are con- 
stitutional in the plants, and undoubt- 
edly are inherited. The cause of club- 
leaf was not determined, but leaf-hop- 
pers were extremely abundant on cot- 
ton, soy beans, egg-plants and other 
crops that are planted together in 
China, and may be suspected of causing 
or transmitting the disorder.’ 
See 
Plant Industry, U. S. Dept. Agriculture, issued April 5, 1913. 
99 
