882 



JOURNAL OF THE ROYAL HORTICULTURATj SOCIETY. 



author held priority, and on this ground alone Johnson was scarcely 

 justified in changing the name of the parasite from Spongospora sohuii, 

 Brunch.-^ to Spongospora suhterranea, Wallr. 



An earlier record of Wallroth's Erysihe siihterranea occurs in 

 Versavi. Deut. Nat. und Aerzte Brauhsehweig, 1 838-1841. ''•^ On Sep- 

 tember 22, 1841, some diseased potatos affected with Erysibe were 

 sent with a letter by Wallroth in Nordhausen to Professor Bartlind . 

 From this it is clear that the organism described by Wallroth in 

 Linncsa w^as already known by the name of Erysihe in 1841. 



The critical remarks which have been made relative to Berkeley's 

 Tuhurcinia apply with almost equal force to Wallroth's Erysibe 

 and Martius' Protomyces. There is no doubt that the three observers 

 were acquainted with the disease itself (potato canker), and that the 

 reproductive bodies of Spongospora' had been observed. But the 

 descriptions of the " organism " in each case are imperfect and incom- 

 plete. On this account, therefore, it seems more desirable to retain 

 ,the name Spongospora solani given to the parasite by Brunchorst 

 than to adopt first this and that name,- as each probing of the older 

 literature of the subject brings to light soriie'new fact. 



5. Field Observations. 



Amongst the cases of canker reported in the Journal of the Board 

 of Agriculture in November 1909, only one is mentioned as occurring 

 amongst a field-crop of potatos. Several cases of the disease which I 

 saw during a visit to Scotland in September 1910, however, occurred 

 in the field: particularly in the Dunbar district, at Prestonpans 

 in the Edinburgh district, and in Aberdeenshire. One of the worst; 

 cases affecting a field-crop in the county of Durham is worthy of 

 special notice, in that experimental work was in progress on the farm 

 in connexion with potato disease. In 1909 the crop suffered severel 

 from an attack of Phyiophthora infestans, and it was decided to la 

 out a number of experimental rows, using different varieties- of potatos 

 in order to test their disease-resisting power under the circumstances 

 of soil and climate which obtained on this particular farm. The p6tatos 

 were derived from several different sources, and only carefully selected 

 tubers were planted. The varieties and their origin are shown in the 

 following table: — ' . * 



Table I. 



Variety. Source of Seed, etc. 



1. Dalhousie . 



2. Midlothian Early 



3. British Queen 



4. Snowdrop . 



5. Duke of Albany . 



6. King Edward VII. 



7. Duke of York 



8. Collingwood 



9. Sir John Llewelyn 



Scotch seed, 1910, used for the main crop. 

 Selected from seed raised in the Armstrong College 



garden — newly made soil — in 1909. 

 Purchased locally. 



from another source. 



* Bartling, " Ueber Wallroth's eingesamte kranke Kartoffeln " (Sept. 22 

 1841), Ic. 



