[Cir. 120—D.] 
-LEAF-CUT, OR TOMOSIS, A DISORDER OF COTTON SEEDLINGS: 
By O. F. Coox, Bionomist in Charge of Crop Acclimatization and Adaptation 
Investigations. 
INTRODUCTION, 
Seedlings and young cotton plants are subject to a peculiar disorder 
that results in extensive injury to the leaves and frequent abortion 
of the terminal bud. While these injuries are seldom fatal, they 
undoubtedly impede the growth of the plants, delay the period of 
production, and reduce the crop. Though not taken into account 
hitherto, the losses occasioned by the leaf-cut disorder, though most 
severe in the Southwestern States, seem to be very general and must 
amount to millions of dollars every year. With the advance of the 
boll weevil this form of injury to the young plants acquires a more 
serious aspect, because it is of the utmost importance to shorten the 
period of production in order to avoid damage by the weevil. The 
leaf-cut handicap can be reduced by improved cultural methods, as 
stated in previous publications of the Bureau of Plant Industry.’ 
LEAF-CUT DISTINGUISHED FROM LEAF-CURL. 
Leaf-cut is suggested as a popular name because mutilations of the 
leaves are the most characteristic symptom of the disorder. The name 
“Juvenile leaf-curl”’ has been applied in previous publications, but 
is inconveniently long and not sufficiently distinctive. Moreover, 
the leaves of cotton seedlings are subject to another malformation, 
induced by plant lice, for which the name “ leaf-curl ” 1s more appro- 
priate. 
Leaf-cut is very widely distributed and familiar to planters, though 
generally confused with the leaf-curl caused by plant lice. Though 
both forms of injury are likely to be found in the same field, or even 
on the same individual plant, they are easily distinguished. (Fig. 1.) 
The leaf-curl is a crumpling or arching up of the leaf between the 
veins, but without perforations or rents. Even in cases of great dis- 
tortion by leaf-curl the tissues of the leaf are left entire, without 
1TIssued Apr. 5, 19138. 
2See Report of the Chief of the Bureau of Plant Industry, U. 8S. Department of Agri- 
culture, for 1911, p. 24; for 1912, p. 27; and U. S. Department of Agriculture, Bureau of 
Plant Industry, Circular 96, p. 18. 
[Cir. 120] 29 
