COTTON IN WEEVIL-CONTROL EXPERIMENTS 



25 



not produce squares until the emergence of weevils from hibernation 

 had been completed. Poison applied before the appearance of 

 squares in early-planted cotton would be less effective, as late emerg- 

 ing weevils would reinf est the field. 



DEVELOPMENT OF PLANTS IN THINNED AND UNTHINNED ROWS 



In order to compare the development of the plants in thinned and 

 in unthinned cotton, records of plant height and number of nodes 

 on the main stalk, the number of squares produced, and the number 

 of internodes on the fruiting branches were obtained on 10 repre- 

 sentative plants of each spacing. These records were started on 

 June 27 and were taken at oiweekly intervals until August 9. 



The average number of internodes on the main stalk and the height 

 of plants on June 27 were practically the same on plants which had 

 been thinned to two in a hill on June 15 and on plants left un thinned. 

 Those in both spacings averaged 11.1 nodes on this date, while the 

 height averaged 28.8 centimeters for . unthinned and 28.9 centi- 

 meters for the thinned plants. 



The number of internodes on plants of both spacings remained 

 practically equal throughout the period during which data were 

 obtained. The final records, obtained on August 9, showed that the 

 unthinned plants averaged 17.2 internodes, while the thinned plants 

 averaged 18 internodes on the main stalk. The thinned plants had 

 grown to a slightly greater size, however, their height averaging 

 67.3 centimeters, as compared with 63.2 centimeters on those un- 

 thinned. It is apparent that different plant spacings had a negli- 

 gible effect on the development of internodes of the main stalk and 

 on the height of the plants. The dry weather at San Antonio during 

 this season retarded the development of all plants, and it is possible 

 that greater differences in the size of plants would have resulted if 

 more moisture had been available. 



Although the development of the main stalk was the same on 

 thinned and unthinned plants in this test, the thinned plants had a 

 larger number of internodes formed on the fruiting branches, as 

 shown by records obtained on August 9, when the growth of all 

 plants had practically stopped. These data, showing the compara- 

 tive nodal development of groups of fruiting branches on thinned 

 and unthinned plants, are presented in Table 14. The thinned 

 plants had a consistently larger number of internodes on each group 

 of fruiting branches than the unthinned plants. 



Table 14. — Number of squares on plants and average number of internodes on 

 fruiting branches of thinned and unthinned plants in a late-planting test of cotton 

 at Han Antonio in 1923 



Plant spaciDg 



Total number of squares on plants at 

 2-week periods 



Average number of internodes 

 on fruiting branches on 

 August 9 



. 



June 27 



July 12 



July 25 



August 9 



Branches 

 lto4 



Branches 

 5 to 8 



Branches 

 9 to 12 





10.6 



10.1 



18.7 

 22.9 



24.1 

 30.6 



25.4 

 34.0 



1.8 

 2.3 



2.4 

 3.2 



1.7 



Thinned (two plants in a hill).. 



2.3 





