THE BOLL WEEVIL — LOFTIN 291 



disease control as one of the major needs in the more economical pro- 

 duction of cotton. 



The importance of early fall destruction of cotton stalks in reducing 

 the fall build-up of weevils has been recognized but not as generally 

 used as it should be because of the difficulties in getting cotton picked 

 before frost. The recent development of chemical defoliation of cotton 

 plants may overcome this obstacle and have far-reaching effects on boll- 

 weevil control. Dusting with 20 to 30 pounds of calcium cyanamide 

 per acre causes the leaves, squares, and small bolls to wither and fall 

 from the plants (pi. 10, fig. 2) and the large bolls to open normally 

 within 3 or 4 days just as a frost does. The removal of the leaves re- 

 duces the trash adhering to the lint, improves mechanically harvested 

 cotton by a full grade, increases the amount that can be picked by hand 

 or mechanically, and permits the harvesting of the entire crop at one 

 operation instead of the two or three pickings formerly required to 

 avoid weather damage to lint. Picking by hand represents one-third of 

 the cost of cotton production, and chemical defoliation removes one of 

 the greatest difficulties in the development and successful use of me- 

 chanical cotton pickers. Calcium cyanamide is a nitrogenous fertilizer 

 and is beneficial to the soil. Its use as a chemical defoliant expanded 

 rapidly during the wartime labor shortage and has already swept 

 across the belt from South Carolina to California. The favorable 

 response to chemical defoliants has started research for other mate- 

 rials to meet the increasing demand. 



The numerous inquiries from returning World War II pilots indi- 

 cate a great expansion in the use of airplanes for pest control. In 

 the past the planes used for dusting have been converted small pas- 

 senger models, but with the recent advances in aeronautical engineer- 

 ing, specially designed aircraft with greater carrying capacity, ma- 

 neuverability, safety and other features better adapted for pest con- 

 trol than those now in use may be expected. Improvements in ground 

 equipment such as the recent tractor-attachment dusters are keeping 

 pace with the increased trend of mechanization of cotton culture and 

 reducing the cost of equipment and labor for weevil control. The new 

 methods of applying insecticides in the form of liquefied gas or thermal 

 aerosols and concentrated sprays are additional weapons for testing 

 against the boll weevil. 



The recent progress in developing many new materials for insect 

 control has stimulated renewed research for a better insecticide than 

 calcium arsenate for the boll weevil. DDT is not the answer for the 

 boll weevil, but if further experimentation confirms the preliminary 

 results, some of the new synthetic insecticides such as benzene hexa- 

 chloride may be the beginning of a new era in boll-weevil control. 



