is:] 



POTATO DISEASES. 



By a. S. HORNE. 



Over seventy years have elapsed since C. E. P. von Martius^ set to 

 work to investigate potato disease in Germany and M. J. Berkeley^ began 

 his observations on the potato murrain, contributed to the Journal of 

 the Royal HorticuUural Society in 1846. These early observers recog- 

 nised that potato disease consisted of several distinct maladies some of 

 which they attributed to fungal organisms, but their knowledge of the 

 diseases and fungi was of necessity incomplete. Von Martius noticed 

 several diseases, notably Stockfaule (gangrene seche or dry-rot), con- 

 sidered to be due to one of the Mucidineae — Fiisisporium solani ; 

 Krauselkrankheit (la frisole or curl), and Rande (gale), prevalent in 

 the calcareous lands of Thuringia, Bavaria and in Austria. Payen^ 

 records in 1853 that Rhizoctonia violacea, the cause of the disease known 

 in France as mort du safron of the lucerne and sanfoin, could also attack 

 the potato. 



The disease known in France as the maladie de la pomme de terre, 

 in Britain as the potato murrain, was regarded by Montague, Morren, 

 Berkeley, Lindley, Payen and others as due to the fungus Botrytis 

 infestans known later as Phyfo])hthora infestans. The means of com- 

 batting the malady adopted in Payen's time were attention to the soil 

 and drainage, the choice of varieties that appeared to have the best 

 chance of escaping the disease, in the preparation of tubers to be used 

 as seed — tubers to be planted should be exposed to dry air and light 

 for some days before planting, whilst a wash of copper sulphate solution 

 similar to that used for grain at that time was recommended — the rotation 

 of crops, and the effect of autumnal planting was studied. It remained 

 for De Bary (1861 — 1876) to present the first clear account of the life- 

 history of Botrytis infestans and to finally settle its position among 



^ C. E. P. von Martius in Die KdHoffel Epidemic der letzen Jahrc oder die Stockfaule und 

 Rdtide der Kartoffeln 1842. 



- M. J. Berkeley in Journal of the Royal Hort. Sac, i, p. 9 (1S4G). 

 ^ Payen in Dcs Maladies dcs pommes de terre, Paris, 1853. 



