CONTROL OF TOBACCO WILT IN THE FLUE-CURED DISTRICT. 



9 



During the four years, 1911 to 1914, inclusive, field plats at Creed- 

 moor, N". C, consisting of single rows, were used in trials with disin- 

 fectants. The usual fertilizing and cultural methods were followed 

 alike on all plats. The results for 1911 and 1912 are shown in part 

 in Table II. The permanganate of potash and chlorid of lime were 

 applied in the same quantities and in double the quantities recom- 

 mended by Honing in Sumatra, the weaker solutions consisting of 

 125 grams of the chemical in 25 gallons of water. The solutions were 

 poured into the holes in which the plants were to be set 24 hours 

 before transplanting. 



Table II. — Field, experiments with tobacco plants, showing the effects of soil 

 disinfectants at Creedmoor, N. C, in 1911 and 1912. 



Year of tests andchemicals used. 



Method and rate of applica- 

 tion. 



Number of plants. 



Percent- 

 age of 

 wilt. 



Wilted. 



Healthy. 



Tests in 1911 (conditional Aug. 12): 



Cheek 





30 

 39 



29 

 27 



23 

 32 



25 

 17 



5 

 27 

 38 

 39 

 35 

 40 

 40 

 26 



1 



4 



2 

 3 



3 

 2 





 1 



37 

 35 

 17 

 22 

 19 

 18 

 12 

 19 



90 8 





Weak solution, 2 quarts per 

 hill. 



90.7 



Check 



93.5 





Weak solution, 2 quarts per 

 hill. 



90 



Check 



88 5 





Strong solution, 2 quarts per 

 hill. 



94.1 



Check 



100 





Strong solution 2 quarts per 

 hill. 



94.4 



'Tests in 1912 (condition -on Aug.. 5): 



Check 



11.9 



Toluol 



50 gallons per acre 



43 5 



Check 



69 1 



Toluol 





63.9 



Check ■ 





64 8 



Toluol 





69 



Check 





76.9 



Check 





57 8 









In 1913 and 1914 the experiments were continued along the same 

 lines, with the use of formalin, sulphuric acid, naphthol, carbolic 

 acid, Bordeaux mixture, atomic sulphur, lime sulphur, coal tar, pine 

 tar, and several proprietary disinfectants. In these tests more than 

 a score of germicides and other chemicals were applied in various 

 quantities and in various ways. Since the same plat was used each 

 year, the cumulative effect of the chemicals was detrimental to the 

 growth of the tobacco. Here, as in the cylinders, it was difficult to 

 secure a good stand of plants. In general, there have been no con- 

 sistent differences in the percentages of wilt in the treated and the 

 untreated rows. The results are confirmatory of the cylinder tests 

 and do not promise success in wilt control through the use of chemi- 

 cals. In 1915 certain materials supposed to contain radium, includ- 

 ing Banque du Radium, carnotite, and a radioactive earth, were tried 

 in several differing quantities at Creedmoor, but without any definite 

 j-esults. 



94919°— Bull. 562—17 2 



