BOLL- WEEVIL COTTON IN TEXAS. 3 



ence in color, but the foliage has the deeper shade of green that 

 usually marks a state of vegetative vigor as distinguished from the 

 more yellowish green of plants in the fruiting stage. An urban 

 writer's account of the boll weevil, that " it bit the tops of? of the 

 cotton plant,*' is quite imaginary. There is no obvious external 

 symptom except the abnormal growth of the plants. 



One consequence of rank growth is the development of more numer- 

 ous and larger vegetative branches, so that the lanes are closed be- 

 tween the rows and the ground shaded continuously. The shading of 

 the ground is an important feature, making the conditions more 

 favorable for the weevils as the season advances. Once the state of 

 boll- weevil cotton is reached the weevils can breed without interrup- 

 tion and maintain themselves in such numbers that all of the buds are 

 destroyed, so that no more flowers appear and no more bolls are 

 set beyond the small number that usually escape the weevils early 

 in the season. With sufficient moisture to support a continuous 

 growth the fields become veritable thickets (PL I, Fig. 1) and show 

 a wilderness of bare stalks in the fall after the leaves are killed by 

 frost. 



The rank growth of the plants may be considered a result of 

 pruning away the floral buds and young bolls by the weevils. This 

 apparently serves, like other pruning, to stimulate additional growth, 

 which is shared by all parts of the plant. The fruiting branches have 

 a continued succession of new joints, each with its small flower bud 

 that the weevils destroy. The later joints of the fruiting branches 

 are shorter and shorter, and many of the late-season flower buds are 

 defective. 



STERILE INVOLUCRES OF BOLL-WEEVIL COTTON. 



That the late-season growth of boll-weevil cotton becomes dis- 

 tinctly abnormal was indicated in 1921 by the production of many 

 defective involucres. (PI. II.) The involucre of the cotton plant 

 is a specialized organ that incloses the floral bud. replacing the 

 function of the calyx, which in cotton is poorly developed. Instead 

 of the three small leaves, or bracts, that form the normal cotton 

 involucres, many involucres of the boll-weevil cotton have only one 

 or two bracts and no other floral organs. Slender rudiments of a 

 calyx were found in some of the 2-bracted involucres, but no petals, 

 stamens, or pistils. 



Reduced budless involucres of similar form have been observed 

 on sterile hybrids and abnormal individual variations of Pima 

 (Egyptian) cotton, as well as in upland sorts, but with no such 

 regularity or frequency as in the boll-weevil cotton of 1921, both 

 at San Antonio and at Greenville. Tex., representing the Lone Star 

 and many other upland varieties. Failure to find any 2-bracted 

 involucres that produced bolls in upland varieties is in contrast 

 with the Egyption type of cotton, where normally developed bolls 

 are often found with involucres of only two bracts. The tendency 

 of upland cotton is to a larger number of bracts. Some of the 

 upland varieties, as Tuxtla and Meade, show frequent variations 

 to 4-bracted involucres, which seldom, if ever, occur in Egyptian 

 cotton. 



