BUREAU OF PLANT INDUSTRY. 173 



stood by those who are not familiar with the structure and habits of 

 the cotton plant to the extent of knowin<^ the differences between the 

 two kinds of branches. The differences are familiar to observant 

 cotton growers, though formerly not recognized or interpreted by 

 writers and teachers, so that a scientific appreciation of the control 

 or suppression of the vegetative branches was not attained. This 

 requirement of direct knowledge of the plant has been a technical 

 difficulty, but now the system is being popularized rapidly through 

 the agricultural press. It is believed that a more general knowledge 

 and use of the single-stalk system in combination with other methods 

 of weevil control previously suggested will render the crop more 

 secure and tend to maintain the production of cotton over the entire 

 Cotton Belt. 



A study of holl-weevil cotton. — The expression " boll- weevil cot- 

 ton " is used by farmers in Texas to describe a secondary effect of 

 weevil injury, an abnormal growth that results from the plants 

 not being allowed to set fruit because the floral buds are destroyed 

 by the weevils. A special study of boll-weevil cotton made in Texas 

 in the season of 1921 yielded further evidence of the abnormal be- 

 havior of the weevil-pruned plants and of the need of restricting the 

 size of the individual plants, which the single-stalk method makes 

 possible. 



The relation between the size of the plants and the extent of weevil 

 injury was shown to be very marked. On the exposed individual plants 

 and the separate rows of cotton with open lanes between, bolls con- 

 tinued to set till late in the season, notwithstanding the great abun- 

 dance of weevils and the complete cessation of fruiting in the closely 

 adjacent fields of boll-weevil cotton. The overgrown boll-weevil 

 cotton represents a hopeless condition from the standpoint of pro- 

 duction, because the weevils are protected, even in dry weather, 

 under a continuous canopy of foliage. Wider separation of the rows 

 is indicated, but closer spacing of the plants in the rows will avoid 

 excessive growth, suppress the vegetative branches, and keep the 

 lanes open. 



Causes of shedding in cotton. — Though the boll weevil is the most 

 prominent cause of the blasting and shedding of the floral buds, or 

 " squares," of cotton, shedding from other causes is of such frequent 

 and general occurrence in the Southern States that some writers 

 have considered it a normal habit of the cotton plant to shed 50 to 

 60 per cent of the buds. As shedding from other causes is more 

 injurious under weevil conditions, because tending to more serious 

 reduction of the crop, the relation of shedding to weevil resistance 

 may be very important. Experiments in some of the irrigated 

 districts of California have demonstrated that shedding is not nor- 

 mal, since it does not occur when the continuously favorable con- 

 ditions are maintained, but any extreme condition may induce shed- 

 ding, either by checking or by forcing the growth of the plants. 

 Some varieties are more susceptible to shedding than others, and 

 the Egyptian type of cotton is notably less susceptible than any of 

 the American upland varieties thus far known. Cultural conditions 

 that determine the size of the plants also have relation to shedding, 

 large plants being more susceptible to injurious checking by drought 

 in comparison with smaller plants under the same conditions. 



