810 
Journal of Agricultural Research 
Vol. XXVIII, No. 8 
conditions, since a larger growth of the plants would result in more serious check¬ 
ing by dry weather later in the season. Cotton that is planted on more open 
bottom-land soils often grows much faster and begins flowering much earlier, but 
is not so likely to mature a good crop as the cotton that grows on the heavy prairie 
soil. 
According to reports from South Africa, serious injuries to cotton may occur 
from insects of the family Jassidae, with distortion and discoloration of the leaves, 
but later recovery of normal habits of growth in the dry season, when the insects 
disappear. Thus the jassid disorder in Africa seems most analogous to hybosis. 
Varieties of cotton with hairy leaves and stems are considered immune to the 
jassid disorder (18). 
CYRTOSIS, OR CLUB-LEAF 
This disorder is most severe in the Asiatic type of cotton, and is a limiting factor 
of cotton production over a wide region in the central part of China (PI. 8). 
The disease apparently is of general and regular occurrence, with the late growth 
of all the plants affected. The development usually is normal to the flowering 
or early fruiting stage, with later abrupt transitions to the club-leaf condition* 
The leaves of the abnormal growth are reduced, distorted, and discolored, with 
mottling of dark and light green, especially along the margins and between the 
principal veins. The internodes and petioles are shortened, and small super¬ 
numerary branches are frequent, so that the abnormal growth may form compact 
masses of foliage, especially in the native Chinese cotton. 5 
When the disorder is severe all of the floral buds may be aborted, so that the 
crop is restricted to the early bolls. Cotton that is planted too late, so that bolls 
are not set before the cyrtosis begins, may remain completely sterile, especially 
under conditions of exposure to dry hot weather, which intensifies the cyrtosis 
symptoms. Thus the cotton suffers less from cyrtosis in the humid coast dis¬ 
tricts around Shanghai and Nantung than farther up the Yangtse Valley, at 
Nanking, Nanchang and Wuchang. In the more northern districts, from Han¬ 
kow to Peking, there is less injury to the crop, on account of a later incidence of 
the disease. 
In Upland and Sea Island cotton grown in China, cyrtosis does not shorten 
the internodes or reduce and curl the leaves to the same extent as in Asiatic 
cotton, so that the aspect of the affected plants is quite different. In Upland 
cotton the distorted leaves have the margins curled under (see PI. 8, E), while in 
Sea Island cotton the margins are tilted up, so that the upper surface of the leaf 
becomes more deeply concave or channeled. 
The occurrence in India of a disease that is closely similar to the cyrtosis 
disorder, if not the same, is shown in a paper by Kottur and Patal (14)' It 
appears, however, from this account that the disease in India is of irregular 
occurrence, instead of being practically universal as in the cotton districts of 
China. This may indicate that most of the Indian cotton is immune to cyrtosis, 
or that the agents or sources of infection are less common than in China. The 
writers ascribe the disease to adverse conditions of growth, and state that it 
occurs much more extensively in some seasons than in others. 
STENOSIS, OR SMALUNG 
f 
The striking feature of stenosis is the extreme reduction in size that may take 
place in the internodes, leaves, and floral organs of the affected plants, in addi¬ 
tion to deformity and discoloration of the leaves, as in the cyrtosis disease of 
* Cook, O. F., a disorder of cotton plants in china ( 6 ). See also Report of The Chief of the Bureau 
of Plant Industry for 1921, p. 23 ( 17 ). 
