26 BULLETIX 332, TJ. S. DEPARTMENT OF AGRICULTURE. 
nearly related to the cotton plant, 1 Neither this weevil nor the true 
Mexican boll weevil has as yet been observed in the cotton fields 
of the Salt River Valley. An aphis commonly attacks the young 
plants, and in 1914 it persisted in large numbers until late in the 
summer, but it has not been shown that this insect causes serious 
damage to the crop. Bollworms occur in small numbers, but have 
not thus far been a source of appreciable damage. The dreaded 
pink bollworm. which has recently played havoc with the cotton 
crop of Egypt, has fortunately not yet been observed in the United 
States, and it is to be hoped that the measures taken by the Federal 
Horticultural Board will prevent its introduction. 
Certain fungous diseases, while rather common, do not appear to 
be severely injurious. The seedling cotton plants are subject to 
attack, especially when cold weather occurs after planting, by a 
species of Ehizoctonia. causing the disorder known as " sore shin." 
When this disease is very prevalent, some replanting is likely to be 
necessary, but the plants which survive soon cease to show any effects 
of the trouble. Small areas, particularly in old fields which have 
previously been in alfalfa, are subject to a root rot. or wilt, 2 which 
toward the end of the summer causes the cotton to die rapidly in 
well-defined spots. The percentage of the total acreage thus affected 
is small, and the disease does not appear to spread rapidly through 
the soil or to be a serious factor in production when a suitable rota- 
tion of crops is followed. 
The cotton seedlings are also subject to a disorder known as leaf- 
cut. 3 which is apparently a physiological derangement not asso- 
ciated with a parasitic organism. The symptoms are mutilation of 
the leaves and sometimes the abortion of the growing point of the 
stem, resulting in the malformation of the plants most seriously 
affected. Since the plants are subject to this disorder only while 
very young, the system of late thinning eliminates its effects by 
permitting the i; chopping " out of the malformed plants. 
CONDITIONS OF SUCCESSFUL EGYPTIAN-COTTON PRODUCTION. 
The experience gained in connection with the establishment of the 
community growing of Egyptian cotton in the Salt Eiver Valley 
makes it possible to formulate the conditions which appear to be 
indispensable to the successful production of this crop in the United 
1 Cook, O. F. A wild host plant of the boll weevil in Arizona. In Science, n. s., v. 37, 
no. 946, p. 259-261. 1913. 
Bailey, Vernon. The wild cotton plant (Thurteria thespesioides) in Arizona. In Bnl. 
Torrey Bot. Club. v. 41. no. 5, p. 301-306, 2 fig. 1914. 
Coad, B. It. Relation of the Arizona wild cotton weevil to cotton planting in the arid 
West. TL S. Dept. Agr. Bui. 233, 12 p., 4 pi. 1915. 
2 The identity of this disease has not yet been established. 
3 Cook, O. F. Leaf-cut. or tomosis. a disorder of cotton seedlings. In U. S. Dept. Agr., 
Bur. Plant Indus. Circ. 120, p. 29-34, 1 fig. 1913. 
