TOBACCO RESISTANT TO BLACK ROOT ROT 19 



Examination of weather records for Massachusetts showed years in each peri- 

 od when all or a large part of the tobacco growing season was unfavorable to 

 good tobacco production. Excessively wet seasons occurred as frequently in the 

 later as in the earlier period. The average temperature of the growing seasons 

 of the later period was only slightly higher than in the earlier period. The 

 average temperatures of all the tobacco growing seasons of both periods fell within 

 the range of 18° to 23" C. (64.4° to 73.4°F.), with the temperatures of approxi- 

 mately half the years of each period falling within the lower half of the range. 

 In no growing season of either period did e.xcessive rainfall and unusuall}- low 

 temperatures occur simultaneously for any considerable length of time. It is 

 improbable, therefore, that weather conditions could have caused the differences 

 in yields of tobacco of the two periods. 



So far as it is possible to learn, the cultural practices emplo\ed during the two 

 periods did not differ much. Such differences as existed were largely in the kinds 

 of fertilizers used rather than in the amounts of plant nutrients supplied. Dur- 

 ing the earlier period it was customary to fertilize tobacco with three to four 

 cords of barnyard manure, supplemented with a ton or more of suitable com- 

 mercial fertilizer (4). During the later period, because of the difficulty of getting 

 barnyard manure, it became the practice to fertilize tobacco almost entirely with 

 commercial fertilizer. Although some farmers used more, it was customary.' for 

 naost of them to use a ton and a half of fertilizer per acre, and this supplied little 

 if any more plant food than did the manure and supplementary- fertilizer used 

 during the earlier period. It is improbable that any changes in cultural practices 

 were sufficient to cause the difference in yields of tobacco of the two periods. 



It has often been suggested that the increase in \ ields per acre of Havana Seed 

 tobacco during the last few years was due principally to the fact that the crops 

 of the later years were grown on a reduced acreage and probably on the choicest 

 tobacco land. Examination of the crop records of Massachusetts lor the two 

 periods 1921-32 and 1933-44, however, shows that the decrease in acreage came 

 largeh- in the earlier period and that there has been a general increase in acreage 

 during the later period. Reduced acreage, therefore, does not fully account for 

 the increased yields obtained in the State during the last few years. 



Differences in disease resistance and other inherent properties for productive- 

 ness of the strains of Havana Seed grown could well have influenced the tobacco 

 production of the two periods. In this connection it is of interest that Havana 

 211 was first distributed to farmers in a limited way in 1933. Although there 

 are no records of the acreage grown, it is well known that it increased from year 

 to year and was larger during the last several years. It seems that the difference 

 in tobacco production of the two periods, 1921-32 and 1933-44, inclusive, may 

 be reasonably attributed, for the most part, to the growing of Havana 211 during 

 the latter period. And if this interpretation is correct, Havana 211 has been 

 largely instrumental in increasing the cash income of man}- farmers who grow 

 Havana Seed tobacco. 



