EXPERIMENT STATION REPORT. 543 



clayey one, in which tlie water is held and air enters witli diliiculty. 

 From tlie nature of tin' disease it is not expected that ajiyone would 

 think of attempting a second crop upon an infected field until some 

 years have elapsed. Probably much of the trouble arises from tlu; 

 seed not being free from the disease. If possible, the potatoes for 

 planting should be obtained from a locality where rot has not pre- 

 vailed. The tubers for seed may be soaked in a solution of bluestone 

 (sulphate of copper) before planting. Some recommend placing the 

 *'^seed" in an oven for a few moments, heated to near a hundred de- 

 grees. If possi])le, phmt upon a naturally dry or well-drained soil, 

 and hill up the earth well around the vines at the last plowing, thus 

 giving a good covering to the potatoes and making it less easy for 

 the germs to reach the tubers through the soil. 



Historical. 



Concerning the history of the disease above considered, Dr. Farlow* 

 has written : "At times its advent is so sudden that within a few hours 

 the potato fields change from green to brown and black, and the 

 plants which in the morning gave promise of an abundant croj), be- 

 fore night might present a mass of decaying vegetation, in which are 

 involved not only the leaves and stems, but also the tubers. Tlie dis- 

 ease occurred in this violent form in 1843 and again in 1845, and 

 spread over a good part of the United State and the British Provinces, 

 and also destroyed the crop in Great Britain, Ireland, Belgium and 

 parts of Germany and France. The greatest injury was done in Nova 

 Scotia, New Brunswick and Ireland, owing to the fact that in these 

 countries the potato was the principal crop. Since 1845 the disease 

 has recurred, ])ut never with such violence, although during the year 

 1874 the damage was consideral)le. Although public attention was 

 first called to tlie I'ot in 1842, it is not likely that it then appeared 

 for the first time, but we must sxippose that some of the vaguely- 

 described epidemics of the last century were of the same nature. 



"It is with sudden and violent outbreaks, as those of 1842 and 1845, 

 that in the public mind the potato rot is associated. As a rule, how- 

 ever, the disease is of a milder type." 



Since 1889 there has been, in New Jersey, one very w,>t Julv, 

 namely, in 1897, when the rainfall reached the total average for the 



*The Potato Rot — Bulletin of the Bussey Institution, Harvard University, 1875. 



