280 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1945 



has been proved by placing weevils in hibernation cages at different 

 dates to simulate depriving them of food under field conditions. In 

 a long series of experiments at Tallulah, La., no survival occurred 

 when weevils were installed in cages during the first week in Sep- 

 tember, while the highest survival (2.55 to 2.92 percent) was from 

 installations during the last half of October and first half of Novem- 

 ber, the period when the frost normally kills cotton and weevils 

 enter hibernation under natural conditions (U. S. Dep. Agr. Techn. 

 Bull. 486). 



Numerous agronomic practices, such as thorough preparation of the 

 seed bed, the use of commercial fertilizers, early planting, frequent and 

 thorough cultivation, that stimulate rapid growth and maturity are of 

 great value in evading damage. Perhaps no recommendation aroused 

 more controversy than early planting, because many people believed 

 that late planting would permit the overwintered weevils to emerge 

 from hibernation and die before squares became available for food. 

 Numerous experiments and actual farm experience have definitely 

 proved the fallacy of this reasoning, and planting as early as the 

 danger of frost has passed is now almost universally practiced. An 

 outstanding contribution by agronomists was the discovery that delay- 

 ing thinning until the plants were several inches tall and leaving the 

 plants thick in the drill suppressed the formation of vegetative 

 branches and stimulated early fruiting. These modifications in cul- 

 tural practices and changes to new varieties have changed the early 

 fields of from 5,000 to 6,000 large, heavily branched cotton plants per 

 acre that fruited until late in the season to 10,000 to 15,000 smaller 

 and more upright plants that produce fewer bolls per plant but more 

 bolls per acre in a much shorter time. Many of these improvements 

 in cultural methods and increase in yield would have occurred in the 

 normal course of events, but the aid given cotton growers in fighting 

 the boll weevil has done much to overcome the traditional slowness of 

 the South in adopting changes. 



EFFECT OF BOLL WEEVILS ON COTTON VARIETIES 



The types and varieties of cotton grown in the boll-weevil infested 

 areas have undergone material changes which have aided more in 

 reducing weevil damage than is generally realized. The first changes 

 in varieties to meet weevil conditions increased the production of short- 

 staple, inferior cotton which became difficult to market. This surplus 

 of low-grade cotton still plagues the industry, and the lack of markets 

 has stimulated the development of improved varieties with better 

 staple. Cotton is a perennial but has grown under cultivation for 

 centuries as an annual. The plant has the peculiar habit of producing 

 squares and bolls in successive zones, as the fruiting branches form on 



