16 



BULLETIN 1320', U. S. DEPARTMENT OP AGRICULTURE 



SHEDDING OF SQUARES FROM WEEVIL INJURY 



As previously stated, the first indication of weevil infestation after 

 the removal of squares and the application of poison was noted 

 during the last week in June. The progress of the infestation is 

 shown by records of weevil damage during the period from June 25 

 to July 31. These records were obtained by counting the number 

 of weevil-punctured squares that were shed during 2-day intervals 

 from a 50-foot section of a row in each block of each planting. These 

 data are graphically shown in Figure 6, the total number of shed 

 squares from the two blocks in each planting being combined in each 

 curve. 



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Fig. 6.— Number of weevil-shed squares from two 50-foot sections of rows in each planting of cotton at San 



Antonio, Tex. 



The first weevil-shed squares in the April 19 planting were found 

 on June 29 and in each of the three later plantings by July 7. The 

 first planting showed a higher rate of square shedding during the first 

 half of July, but the extent of weevil damage in all plantings was 

 practically the same by the 19th of that month. The number of 

 squares shed from the first planting decreased after this date, but 

 increased very rapidly in each of the later plantings. 



This abrupt shift in the extent of shedding is due to the fact that 

 there were more squares on plants in the later plantings during the 

 last half of July. It is probable that the absence of squares on the 

 early plants resulted in a concentration of weevils on the later plant- 

 ings. This condition of heavy weevil infestation in the late-planted 



