COTTON IN WEEVIL-CONTROL EXPERIMENTS 9 



Although the field became reinfested with weevils after square 

 removal and poisoning, the degree of infestation was much less than 

 in untreated early-planted fields on other parts of the experiment 

 farm. Possibly a more effective control might have been obtained 

 if the measures had been applied earlier than June "12, as fewer 

 infested squares would have been shed before the square-stripping 

 operation. 



PLANT GROWTH DURING THE FRUITING PERIOD 



Records of the nodal growth of the cotton plants, the rate of 

 flowering, and the extent of boll shedding were obtained from each 

 of the four plantings. Comparisons of the rate of formation of 

 internodes were obtained from 10 representative plants in each plant- 

 ing, while the flower counts and boll sheds were recorded from 50-foot 

 sections of rows. 



The records of plant development following the appearance of 

 squares were obtained from diagrams of the same plants which were 

 used in comparing the rate of growth during the seedling stages. 

 These diagrams were made at weekly intervals throughout the period 

 of fruiting of the plants, the final records having been made on August 

 11, after growth had practically ceased. 



A comparison of the rate of formation of internodes on plants in 

 the successive plantings is shown in Table 6, which gives the average 

 number of nodes on 10 plants of each planting on the date when 

 squares were first recorded and 14, 28, and 56 days later. As the 

 first squares were recorded on different dates, it should be noted that 

 the nodal development of the plants in each planting is compared 

 during similar stages of growth and not on the same dates. 



Table 6. — Development of nodes on the main stalk during the fruiting stage of cotton 

 plants grown in successive plantings at San Antonio on four different dates 



Date of planting, 

 1923 



Squares 



first 

 recorded 



Number of nodes at stated intervals after first appearance of squares 



14-day interval 



Actual 



In- 

 crease 



28-day interval 



Actual 



In- 

 crease 



56-day interval 



Actual 



In- 

 crease 



Total 



Prob- 

 able 

 error 



Apr. 19 June 1 



Apr. 28 June 8 



May 5 .....do 



May 12 June 15 



6.5 

 7.0 



6.2 



11.2 

 11.5 

 10.9 

 11.8 



4.7 

 4.5 

 4.7 

 5.9 



14.8 

 14.9 

 14.2 

 15.1 



3.6 

 3.4 

 3.3 

 3.3 



18.6 

 18.2 

 16.9 

 18.9 



3.8 

 3.3 

 2.7 

 3.8 



12.1 

 11.2 

 10.7 

 13.0 



±0.15 



± .22 

 ± .37 



± .22 



The average number of nodes produced on the main stalk during 

 the first period of 14 days after the appearance of squares was 4.7, 



4.5, and 4.7 nodes, respectively, on plants of the first three plantings. 

 The planting of May 12, however, formed 5.9 nodes during this 

 period. During the second period of 14 days the rate of formation 

 of nodes was much slower, the increase in number of nodes having been 



3.6, 3.4, 3.3, and 3.3, respectively. The final period comprised 28 

 days, but the increase in number of nodes was only 3.8, 3.3, 2.7, and 

 3.8, or about the same as during the preceding period of 14 days. 

 The total number of nodes formed during the entire period of 56 

 davs after the appearance of the first squares was 12.1 nodes on plants 



20718°— 25t 2 



