PRODUCTION OF AMERICAN EGYPTIAN COTTON. 25 
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 and of Mexico, was discovered in 1917 at a few 
localities in Texas, but has not been observed in Arizona and Cali- 
fornia. It is to be hoped that measures taken by the Federal Horti- 
cultural Board will prevent its becoming, established in the United 
States. 
A sucking bug, of the group known as “cotton stainers,” has 
recently caused some damage to cotton in Arizona.* 
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 Rhizoctonia, 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, 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 rotation of crops is 
followed. 
The cotton seedlings are also subject to a disorder known as leaf- 
cut,? which is apparently a physiological derangement not asso- 
clated 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 “ 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 River Valley 
Bailey, Vernon. The wild’ cotton: plant (Thurberia thespesioidés) in Arizona. In Bul. 
Torrey Bot. Club, v. 41, no. 5, pp. 301-306, 2 fig. 1914. 
Coad, B. R. Relation of the Arizona wild cotton weevil to cotton planting: in the arid 
West. U.S. Dept. Agr. Bul. 233, 12 p., 4 pl. 1915. . 
+Morrill, A. W. WHighth Ann. Rpt., Arizona Comm. Agriculture.and Horticulture, 1916, 
pp. 46-48. 
2Cook, O. F. Leaf-cut, or tomosis, a disorder of cotton seedlings. In U. S. Dept. Agr., 
Bur. Plant Indus. Cir. 120, pp. 29-34, 1 fig. 1913. 
