20 RELATION OF DROUGHT TO WEEVIL RESISTANCE IN COTTON. 



A later date in flowering is not to be reckoned as a lessening of 

 weevil resistance if a variety sets its frnits with sufficient rapidity 

 after flowering has begun. Until the flower buds are about half 

 grown the weevils can not begin to reproduce. The rapidity with 

 which bolls are developed within a specified time after the buds are 

 large enough to allow the weevils to begin to breed would serve as a 

 measure of weevil resistance in experiments with varieties in humid 

 regions. It is important to establish such standards and to apply 

 them to all varieties that are to be grown under weevil conditions, 

 whether the weevils are already present or not. 



In attempting to determine the rate of setting of the crop in dif- 

 ferent varieties, special precautions must be used. It is not sufficient 

 to compare the yield in early pickings, for this will give an undue 

 advantage to the factor of early opening in small-boiled varieties. 

 Neither is it sufficient to determine the tendency to frnit production 

 by the daily counting of flowers on experimental rows or plats repre- 

 senting the different varieties. Allowance must be made for the 

 fact that a big-boll variety does not need to produce as many flowers 

 in order to set the same amount of crop in the same number of 

 days as a small-boll variety. Daily countings of the numbers of 

 flowers on adjacent rows of different varieties may also be rendered 

 unreliable by differences in shedding, some varieties dropping their 

 buds and young bolls much more readily than others. 



The counting of the full-grown bolls at different dates would 

 give an indication of the crop-setting habits if there were any ready 

 means of detennining when the bolls have reached full size. For 

 the most accurate determination it would be desirable to make counts 

 of the bolls as fast as they became large enough to escape weevil 

 injury, though it would still be necessary to take into account the 

 differing amounts of cotton represented by the same numbers of bolls 

 of different varieties. 



It may be that the rapidity with which the bolls are opened cor- 

 responds to that with which they are set, but there is no definite 

 information on this point. It has been noticed in some plantings of 

 Mexican cotton that the bolls seemed to open more nearly together 

 than those of the Triumph cotton and other United States Upland 

 varieties grown in the same places. The rate of opening of the 

 bolls dej^ends very largely on tlie weather at the time when the bolls 

 reach maturity, but these experiments were made under dry condi- 

 tions, with equal opportunities for opening. 



It was generally assumed at first that small-boll varieties must 

 have a distinct advantage in weevil resistance because of earlier 

 flowering and earlier ojiening of the bolls. Large importations of 

 seed of the King and other small-boll varieties from the Carolinas 

 were brought in to replace the Texas big-boll sorts in weevil-infested 



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