COTTON IN WEEVIL-CONTROL EXPERIMENTS 27 



20 all open bolls were picked, and the number of good and weevil- 

 damaged locks was recorded. Similar data were obtained for bolls 

 which opened between August 20 and September 1 and between 

 September 1 and September 18. 



A total of 211 bolls was picked from the two sections of rows on 

 August 20. Of these bolls only 25 locks showed signs of weevil dam- 

 age, representing 2.6 per cent of the total number of locks. On 

 September 1, 613 bolls were picked, and 17.9 per cent of the locks 

 were found to be damaged. Of 259 bolls picked on September 18, 

 34 per cent had damaged locks. A total of 18.8 per cent of the locks 

 was damaged on the 1,083 bolls picked during the season. This 

 weevil injury to bolls was much less than occurred in the other 

 experiment on the cotton planted on the same date but between the 

 earlier plantings. As shown in Table 11, the May 12 planting in 

 the comparison of successive adjacent plantings had 33.9 per cent 

 of all the locks damaged by weevils instead of 18 per cent in the 

 separate late planting. This shows that even a slight isolation of 

 the late plants had a notable effect upon weevil infestation and the 

 resultant injury to the crop. 



YIELDS FROM THINNED AND FROM UNTHINNED ROWS 



The late-planted cotton was picked on September 18, at which 

 time all bolls had opened. The field was divided into two equal sec- 

 tions by drawing lines across it at right angles to the rows, and the 

 weight of seed cotton from each section of each row was recorded 

 separately. The length of rows in each section was 100 feet. 



The row yields from this test are presented graphically in Figure 

 7 in comparison with the row yields obtained from the successive 

 plantings. The yields and number of plants per row in the late- 

 planting test are given in Table 16. 



The row yields of seed cotton indicate that soil conditions were very- 

 uniform throughout the field. Most of the difference in row yields 

 resulted from imperfect stands, some of the rows having short sec- 

 tions with no plants or with a very irregular stand. This irregu- 

 larity in stand interfered with an accurate comparison of the two 

 systems of plant spacing, as some of the unthinned rows had fewer 

 plants than some rows which had been thinned to two plants in a 

 hill. The poorest stands occurred consistently on the outside rows 

 of each block. As a 2-row planter was used it is probable that these 

 thin stands were due to faulty operation of one side of the planter. 



In view of the better stands on the two inside rows of each block, a 

 more accurate comparison of yields may be obtained from these rows. 

 The total yield of seed cotton from the inside rows of the three 

 blocks of unthinned cotton was 67.07 pounds, as compared with a 

 yield of 61.97 pounds from the inside rows of the three thinned 

 blocks. From these weights the mean yield of one 200-foot row of 

 unthinned cotton was found to be 11.18 ±0.31 pounds, while the 

 mean yield of an equal length of row of thinned cotton was 10.33 ± 0.45 

 pounds. 



The difference in average yield of seed cotton between the unthinned 

 rows and the rows which were thinned to two plants in a hill with 

 hills 12 inches apart is less than twice the probable error, indicating 

 that there was no significant difference in yield between the thinned 



