51 



The table shows that the period of storage extends over two sum- 

 mers, from March 7, 1903, to November, 1904. Throughout this 

 entire period the cowpeas kept in cold storage were not injured by 

 weevils and showed practically no deterioration in vitality. On the 

 other hand, the cowpeas stored in " trade conditions " were all de- 

 stroyed by weevils during the first summer. The bulk lot kept in the 

 seed laboratory, Bureau of Plant Industry, where the temperature 

 Avas ver}- favorable for the development of the weevils, was the first 

 to be destroA^ed. In May, 1903, this seed germinated 81 per cent, but 

 one month later the weevils had destroyed every seed. At this time 

 the beetles were present in such numbers as to cause a rise in tempera- 

 ture within the bag of seed of 11.5° C. (20.7° F.). Samples from 

 Jacksonville germinated 90.5 per cent in jMay and 94.5 per cent in 

 June, 1903, but by the 1st of July the seed had been destroyed by 

 Aveevils. The seed stored at Richmond was not all destroyed until 

 the August test. The Washington and New Orleans series showed 

 complete failure in the September test, but in each of these cases many 

 seeds were destroyed at the time earlier tests were made. 



The foregoing results with the cowpeas kept in " trade conditions " 

 illustrate exactly Avhat has been experienced by every seedsman who 

 has attempted to carry cowpeas over the summer in his warehouse. 

 However, Avhere the seeds are handled in large bulk they will be de- 

 stroyed much earlier in the season, as a result of the heat generated 

 by the weevils during the transformation stage. As a result of this 

 heat the second brood will develop much more quickly than w^as the 

 case with small lots as used for these experiments. The actual com- 

 mercial conditions with seed stored in quantity would be much the 

 same as shown in the control sample stored in the seed laboratory — 

 that is, the seed would be destroyed earlier in the season. Plate II 

 shows cowpeas which were kept in " trade conditions " (fig. 1) and in 

 cold storage (fig. 2) at Washington, D. C. The j^hotographs were 

 taken September 1. 1903, approximately six months after the seeds 

 were stored. Figure 1 shows the weevil-eaten cowpeas, which failed 

 to show a single germinable seed ; figure 2, the cowpeas after six 

 months in cold storage. These cowpeas had not deteriorated in vital- 

 ity and germinated 84 per cent. 



EFFECT OF COLD STORAGE ON THE VITAIJTY OF THE SEED AND THE FUTURE 

 DEVELOPMENT OF THE WEEVILS. 



The samples of seed Avere tested for germination as they were 

 taken from cold storage. The remainder of each sample was then 

 stored in tin boxes. The temperature of the laboratory where the 

 seeds were stored was slightly higher than that of the ordinary living- 

 room 



