24 



of labor in the grading and sorting of the finer grades. It is often 

 more profitable to raise a large quantity of inferior leaf than to raise 

 a small weight per acre of a finer leaf which can not be economically 

 sorted. This question, therefore, depends to a very great extent upon 

 local conditions, and especially upon labor conditions. 



DISEASES OF TOBACCO. 



The diseases to which most attention has been given are those which 

 manifest themselves during the curing process and which are com- 

 monly known as stem rot and pole burn. This latter disease is also 

 referred to as " pole sweat" and "house burn." Both of these diseases 

 were observed and studied by the Connecticut State Station during 

 several seasons. As observed by this station, 1 pole burn makes its 

 appearance as small dark spots on the surface of the leaf near the 

 veins and midrib, where moisture is most abundant. These spots rap 

 idly increase in size, soon becoming confluent, and within thirty-six to 

 forty-eight hours the whole leaf may be affected and the entire contents 

 of the curing barn destroyed. The tobacco changes in color from a 

 green yellow to a dark brown, or almost black, loses its fine texture, 

 and reaches such a stage of decay that the leaves are separated from 

 the stalk by their own weight. From investigations made at the sta- 

 tion and results obtained b} T other investigators of this same subject, 

 the author infers that the disease is due primarily to a fungous growth 

 which attacks the leaf on the surface and gives access to a bacterial 

 process of decay b}^ disintegrating and partially destroying the leaf 

 tissue. 



Cultures of the bacteria which caused this rapid decay of the leaf 

 were studied in the laboratory, and it was ascertained that moisture 

 and temperature have a marked effect on the activity of these organ- 

 isms. Decreasing the amount of moisture decreased their vitality, 

 and a temperature up to 70° F. or even 90° F. favored their develop- 

 ment, while temperatures of over 100° or 110° and below 35° or 40° 

 temporarily or permanently checked their vitality. Attempts to inoc- 

 ulate thoroughly cured tobacco with the bacteria were unsuccessful. 

 The author concludes from his study that pole burn can be prevented 

 by a proper regulation of moisture and temperature. 



In 1893, 2 although conditions were most favorable for curing 

 tobacco, an experiment was conducted to test the effect of artificial 

 heat on the temperature and relative humidity of the air in a tightly- 

 closed barn filled with green tobacco. A number of observations were 

 made in each case and average results determined. The temperature, 

 of the outside atmosphere was 57° F. and the relative humidity 70°. 

 Inside the barn the temperature was 54° and the relative humidity 82°. 

 Opening the end doors and the lowest row of ventilators in fair weather 



1 Connecticut State Station, Kept., 1891. 2 Ibid. 1893. 



