8 



BULLETIN 1320, U. S. DEPARTMENT OF AGRICULTURE 



Elantings. A hand gun was used in dusting the plants, the poison 

 eing applied at the rate of about 8 pounds per 'acre. It remained on 

 the plants until June 17, when most of it was washed off by a light 

 rain. No further poisoning was attempted during the remainder 

 of the season. 



A comparison of the development of plants in the four plantings 

 was made on June 15, three days after squares had been removed 

 and poison applied. Data on the height of plants, the number of 

 nodes on the main stalk, the total number of squares that had been 

 formed to June 15, and the actual number of squares on the plants 

 are presented in Table 5. 



Table 5. — Development of cotton plants, showing the average number of squares 

 formed on each plant on June 15 as grown in successive plantings at San Antonio 

 on four different dates 



Date planted, 1923 



Height 

 (centi- 

 meters) 



Number 

 of nodes 



Average number of 

 squares on plants 



Formed 



to June 



15 



Remain- 

 ing on 

 June 15 



Apr. 19 

 Apr. 28. 

 May 5. 

 May 12 



28.6 

 28.0 



27.8 

 24.3 



11.2 

 9.2 

 8.6 

 5.9 



10.6 

 6.5 



5.7 

 1.7 



5.9 

 5.1 

 5.4 

 1.7 



The difference between the total number of squares that had been 

 formed by June 15 and the number actually on the plants at that 

 date represents the loss through square removal and shedding. 

 Considerable shedding of very small squares occurred in the April 

 19 planting, practically all of the squares formed prior to June 1 

 having been shed by June 8. 



WEEVIL INFESTATION AFTER STRIPPING SQUARES 



Although the young squares on the first three plantings had 

 developed within a week after stripping and poisoning to a size 

 which would render them susceptible to weevil injury, no indication 

 of infestation was detected for another week, or until June 25. Three 

 small areas of infested plants were observed on that date in widely 

 separated parts of the field. 



The absence of weevil infestation for a period of nearly two weeks 

 after stripping and poisoning indicates that the control measures 

 had practically exterminated the weevils present in the field on June 

 12. It is probable that the slight infestation which was first noted 

 on June 25 resulted from weevils that had emerged from early-punc- 

 tured squares. Some of the squares on the first planting which had 

 been punctured during the first week in June were shed before the 

 plants were stripped. Some of the squares which had been shed 

 previous to stripping might have been missed by laborers. 



Several scattered points of infestation appeared within a few days 

 after the first trace of weevil damage was noted, most of these points 

 occurring in the first planting. Infestation increased slowly, and by 

 the middle of July evidence of weevil injury could be found through- 

 out the field. 



