POWDERY SCAB OF POTATOES. 5 



GEOGRAPHICAL DISTRIBUTION OF POWDERY SCAB. 



Spongospora seems to be quite generally distributed in northern 

 Europe. As early as 1841 it was recorded as existing in Germany, 

 and that it had existed for some time before this is suggested by the 

 fact that among farmers the disease had come to be known by a com- 

 mon name (Kartoffelraude). Frank more recently (1897) has men- 

 tioned its existence in Germany, but he does not think it is generally 

 distributed. That it does exist to some extent, and possibly more 

 than Frank's report indicates, is suggested by the following facts: 



In the spring of 1913 the Bureau of Plant Industry purchased 22 

 different varieties of seed potatoes from two dealers in Germany. 

 When these were received and examined by the inspecting patholo- 

 gist, four of the lots were condemned, being infected with Spongo- 

 spora. 



In 1846 powdery scab was discovered in England by Berkeley in 

 connection with his studies of the potato murrain, the disease which 

 is now known as PTiytoplithora infestans. The little careful study that 

 was given to Spongospora by the pathologists of Berkeley's day may 

 well have been due to the intensive study given to the Phytophthora 

 disease, which at that time threatened to destroy the potato industry 

 of northern Europe. The general distribution of Spongospora in 

 England and Scotland at the present time can readily be seen from 

 the following statement of the Board of Insect and Fungous Pests 

 for 1909: 



It has been reported to the board from many parts of Great Britain, chiefly, how- 

 ever, from those parts where wart disease is also present, or where it has been sus- 

 pected. Cases have been reported from Peebles, Stornoway, Forfar, Fife, Lanark, 

 Aberdeenshire, Sthlingshire, Lancashire, Cumberland, Shropshire, Rorks, W. W., 

 Staffordshire, Wales, Hereford, Somerset, and Worcester. In Scotland, therefore, the 

 disease seems fairly widely distributed, but in England, as might be expected, it 

 appears to be confined to the west, where the rainfall is higher. It is not, however, 

 to be supposed for a moment that anything like all affected localities are here recorded. 



In the spring of the current year the United States Department of 

 Agriculture imported 18 different varieties of potatoes from Scotland 

 for seed purposes, all of which were found to be infected with Spongo- 

 spora and were condemned by the inspecting pathologist. Nine dif- 

 ferent varieties were imported from England for similar purposes and 

 were not allowed to pass, owing to Spongospora infection. 



On October 31, 1913, Mr. W. W. Gilbert, of the Bureau of Plant 

 Industry, collected specimens of powdery scab on potatoes imported 

 into this country from the Netherlands. On November 20 the writer 

 likewise collected Spongospora at New York City on two different 

 shipments from the Netherlands. The following day specimens were 

 taken by Mr. O. A. Pratt and the writer from a shipment coming from 

 Belgium. More recently the disease has been found several times 



