14 MASS. EXPERIMENT STATION BULLETIN 327 



one case on land whicn was relatively free of black root-rot promoting condi- 

 tions, and in the other case on black root-rot land. The controls were grown 

 at sufficiently frequent intervals throughout the experimental areas to provide 

 adequate checking of results. The land used in each case was well suited to 

 the purposes of the experiments, and good tests of the strains were obtained in 

 all respects, except for resistance to black root-rot. Due to certain weather 

 conditions which were unfavorable to a severe development of black root-rot 

 the resistance of the strains to the disease was not subjected to a rigid test, as 

 was indicated by the limited amount of black root-rot which developed on the 

 common Havana Seed control. 



Several of the strains tested in 1934 rated high according to the standards 

 employed. Some of these strains, however, had been tested for so short a time 

 that their characteristics and their worth were insufficiently known. Others 

 had been tested throughout all or a considerable part of the investigation, and 

 rated high eacn year in comparison with the controls. Of the latter, the most 

 important were Strains 13 and 29. Strain 13 and the controls had been grown 

 on root-rot free land for five consecutive years, and on infested land for four 

 consecutive years, including 1934. Strain 29 had been grown on disease-free 

 land for two years, and on diseased land for three years, including 1934. These 

 tests demonstrated that the two strains possessed essential characteristics in 

 high degree, and possibly to the extent of fulfilling the objectives of the inves- 

 tigation. Practical testing of Strain 13 in 1934 on approximately thirty-five 

 acres of land in cooperation with nine growers in numerous places in the Con- 

 necticut Valley tended to confirm this conclusion, at least in the case of Strain 

 13. It seemed that the greatest need in further work with these strains was 

 larger scale testing on the one hand, to make sure that no characteristics of 

 importance had been overlooked; and more extensive trials in cooperation 

 with growers on the other hand, to determine how far these strains might be 

 acceptable to producers and to leaf dealers and manufacturers. Accordingly, 

 to complete the studies, these strains were grown in 1935 in' well-organized 

 and closely supervised experiments on the same amount of land which pre- 

 viously had been used for the small plot testing of all the strains, and the two 

 strains alone were grown in practical tests in cooperation with good growers 

 in various places in the Connecticut Valley. Strain 13 was grown in coopera- 

 ation with fourteen growers, and Strain 29 with nine growers, on areas which 

 ranged from a portion of an acre to as much as fifteen acres per trial. Approx- 

 imately seventy-five acres of Strain 13, and thirty-five acres of Strain 29, were 

 grown. The results of the tests are not yet available. 



The production data of Strains 13 and 29 and the controls for the periods of 

 time indicated are as follows: 



