﻿18 BULLETIN 1374, U. S. DEPARTMENT OF AGEICULTUEE 



shows an increase of 32.42 per cent in shedding of bolls of the infested 

 blooms above that of the uninfested. 



This does not seem to check with the data on which Figure 7 is 

 based. In that case, as has been pointed out, the percentage of 

 infested blooms on the plants (fig. 6) is equally as great as the per- 

 centage of infested fallen forms (fig. 7). These data, however, do 

 not offer a basis for direct comparison. In the first place, the ex- 

 periments were carried out in two different fields in which the rate 

 of natural shed may have been quite different at the time. Then 

 again, Figure 7 represents all shed forms, not indicating what propor- 

 tion of them were blooms. And, lastly, it is possible that the feeding 

 of the larva in the bloom may cause bolls to shed even though the 

 larva does not touch the young boll itself, in which case an examina- 

 tion of the shed boll only, after the bloom has dropped off, would 

 not reveal the fact that its shedding was due to the pink bollworm. 

 The figure, 32.42 per cent increase in the shedding of the bolls of 

 infested blooms, or an increase of 53.1 per cent above that of the 

 uninfested blooms, compares with Loftin's figures ^° of a difference 

 of 26.8 per cent in shed due to the pink bollworm, or an increase in 

 shedding of bolls of infested blooms of 65.7 per cent above that of 

 bolls of uninfested blooms. 



DAMAGE TO MATURE BOLLS 



The damage done by the pink bollworm to bolls that reach maturity 

 has been separated into damage to picked cotton and cotton render- 

 ed unpickable. The latter is the cotton which is left in the field 

 by the pickers, because it is too greatly damaged to be worth picking. 



DAMAGE TO PICKED COTTON 



In 1921 a number of samples of cotton were picked from different 

 fields and experimental plats to obtain samples of lint and seed and 

 to determine the extent to which they were damaged. These 

 samples were obtained by selecting average stalks and picking all 

 pickable bolls from each of these stalks. One hundred bolls were 

 picked for each sample. To obtain a check sample, a number of 

 locks corresponding to 100 bolls and apparently not injured by the 

 pink bollworm were selected, and picked lock by lock. All of these 

 samples were then ginned on a 10-saw hand gin. The damage to 

 the seed was determined by examination at TlahualUo. After 

 repeated disinfection, the lint samples were sent to the Bureau of 

 Markets at Washington for classification and testing. 



DAMAGE TO SEED 



From the seed of every one of the above samples a certain volume, 

 averaging about 1,000 seed, was taken. These samples were carefully 

 examined, the damaged seed was separated from the sound seed, each 

 part was counted and weighed, and from these figures the damage was 

 calculated, expressed as percentage of reduction in weight of the 

 samples due to pink bollworm feeding. This method should give 

 approximately the damage to the seed of the picked cotton. The 

 results of this calculation are given in the column under ''Percentage 

 reduction in weight" in Table 16. This gives the loss in quantity 

 of seed only. There was in addition a loss in quality, but what this 

 amounted to was not determined. 



» U. C. Loftin. K. B. McKinney, and W. K. Hanson. Op. c;t. 



