32 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE, 1049 
COTTON INSECTS 
New Insecticides Effective igainsl Pests of Cotton 
I on cott( ontinued to center around the 
various new Insecticides. Since most cotton growers musl combat 
several pests at i , and most of these materials are selective in 
the pests thai they destroy, various combinatioi tried to find 
thai would be suitable for the control of them all. The results <>f 
experiments conducted by Federal and State workers in L948 were 
i at Baton Rouge, La., in November, al a conference on 1 1 
t research and control, as a basis for the preparation of recom- 
lations for control operations during the ensuing season. 
The tolerance of crops grown in soil containing various insecticides 
is being tested at Florence, S. C, in a S-year crop-rotation experiment 
begun in L947. Benzene hexachloride, alone and mixed with DDT, 
killed some cotton plants the first year, but none of the L947 treatments 
Lad any effect on cotton stands grown in this soil in L948. 
Boll weevil 
The boll weevil caused less damage in 1948 than in any year since 
r.» 1 1. [nfestations were low during June and July, but changes in the 
weather later in the summer brought populations up to a very high 
level by the end of September. 
The new organic insecticides showing most promise for the control 
of the boll weevil were benzene hexachloride and to\a]>hene. When 
either of these material- or calcium arsenate 1 alone, how 
infestations of other insects may develop. Therefore insecticides for 
their control should be included in the treatments. 
In Texas the cotton farmers in four Wharton County communities 
participated in an experimental program for cotton-insect control. 
In three of these communities the most damaging insect was the boll 
1. Toxaphene in the form of a 20-percenl dust was applied to 
acres on 22 farm-. Usually two applications gave control for 
season. The dusted cotton retained it- early squares, and the bolls 
matured at least 3 weeks before cotton in un dusted communities 
nearby. The yield of lint from 55 dusted fields was 1 18 pounds 
per acre, a gam of 138 pounds per acre over the yield from 33 undi 
fields. 
I Mississippi preliminary tests -hewed concentrated -pray- applied 
by airplane at the rate of 2 gallons per Mere to be superior to dusts 
containing the same amount of the same toxicant The spray giving 
the best control contained L.5 pound- of toxaphene plus 0.3 pound of 
eh lord a ne in 2 gallons of emulsion. ( )t her effe t ive formula! ions con- 
tained 1 pound of chlordane, 2 pounds of toxaphene, or sufficient 
technical benzene hexachloride to give 0.3 pound oi the gamma isomer. 
Sprays cost no more to apply, and they can be applied under more 
er conditions and during more hours of the da v. 
I South Carolina dusts containing toxaphene, benzene hexachloride 
DDT, or chlordane plus DD1 i about the same degree of boll 
weevil control and increased (he yield of seed cotton approximately 
LOO percent. Sulfur was included for mite control in all these dusts. 
