BULLETIN" 1320, U. S. DEPARTMENT OF AGRICULTURE 



Table 3. — Relation of temperature to the development of cotton plants as grown in 

 successive plantings at San Antonio on four different dates 



[The temperatures shown (° F.) cover the period from the date of seed germination to the first appearance 



of squares] 



Date planted, 1923 



Date of 

 germi- 

 nation 



Number 

 of days to 

 squaring 



Number 

 of nodes 

 formed 



Average 

 number 

 of days 

 per node 



Average tempera- 

 ture 



Mini- 

 mum 



Maxi- 

 mum 



Apr. 19. 

 Apr. 28. 



May 5. 

 May 12 



Apr. 25 

 May 4 

 May 12 

 May 20 



6.5 

 7.1 

 6.2 

 5.9 



5.7 

 4.9 

 4.4 

 4.4 



64.4 

 66.5 

 68.6 

 70.7 



92.3 

 94.0 



It will be noted that the interval between the development of suc- 

 cessive nodes decreases when higher temperatures occur during the 

 period from germination to the appearance of squares. The average 

 rate of nodal development during the seedling stage of the April 19 

 planting was 5.7 days. During this period the average minimum 

 temperature was 64.4° and the average maximum 88.5° F. The May 

 12 planting averaged 4.4 days per node during the seedling stage of 

 the plants, the average minimum and maximum temperatures having 

 been 70.7° and 94° F., respectively. 



DAMAGE BY OVERWINTERED WEEVILS 



The extent of weevil infestation in the successive plantings of cot- 

 ton was determined on June 5 by recording the numbers and per- 

 centages of squares that had been attacked by weevils. On June 5 

 squares were present only on the April 19 planting. Even on this 

 there were only a few large squares, and it was necessary to examine 

 about 200 plants in order to find. 100 squares that were regarded as 

 over 10 days old. Records of growth of squares have indicated that a 

 period of about 10 days elapses between the time when a square is 

 first visible and the time when it has reached sufficient size to harbor 

 a weevil larva. 2 



In block 1 of the April 19 planting, which was located on the south 

 side of the field, 45 per cent of the squares were punctured by weevils. 

 Block 2, in the center of the field, had 20 per cent of the squares 

 punctured, and block 3, on the north side of the field, had 15 per cent 

 of punctured squares. 



The heavier infestation in block 1 may have been due to the fact 

 that the field adjoined a Johnson grass pasture on the south. A 

 large part of the weevil emergence probably occurred from this 

 pasture, and a large number of the weevils would doubtless remain in 

 the first cotton where squares were found. 



STRIPPING OF FLORAL BUDS OR "SQUARES" 



Squares were removed on June 12 from the first and second plant- 

 ings, and the entire field was poisoned with calcium arsenate. At 

 that time the squares on the third and fourth plantings were below 

 the size for stripping, so that it was necessary only to apply poison. 



1 Martin, R. D., W. W. Ballard, and D. M. Simpson. 

 Jour. Agr. Research, v. 25, p. 202. 1923. 



Growth of fruiting parts in cotton plants. In 



