18(3 Potato Diseases 



(Miicidineae), but G. C. Cunningham^ (1912) suggests its transference 

 to the genus Streptothrix (Schizomycetes) and H. T. Giissow- refers it 

 to Actinomyces. B. F. Lutman^ (1913) has described the pathological 

 anatomy of this scab. To what extent the British scab is due to 

 Oospora scabies has yet to be determined. 



A disease recently described by the writer* and named bruise, owing 

 to the occurrence of greyish or black areas in the flesh of potato tubers 

 which renders them unfit for culinary purposes, appears to be of a physio- 

 logical nature and is perhaps often occasioned by growing potatoes in 

 poor or insufficiently cultivated land. 



Besides the fungal and physiological maladies, there are of course 

 several pests on the animal side. The Colorado beetle scourge of the 

 United States is fortunately not prevalent in these islands. The tuber- 

 boring wire-worm, however, is frequently troublesome. The very 

 much neglected subject of insects injurious to the potato foliage has been 

 recently studied by Professor H. Maxwell Lefroy and the writer and 

 the results obtained will be soon communicated to these Annals. 



I propose now to consider as far as possible in correct perspective 

 only those problems, the insect question excepted, that are of con- 

 siderable economic importance at the present time in Great Britain. 



Tumour. 



The disease caused by CJirf/sojjhlyctis endobiotica — the tumour 

 organism — has claimed considerable attention during the last few years, 

 firstly owing to reports of an alarming kind relative to the virulence 

 of this parasite and fear lest it might spread and eventually ruin the 

 potato-growing industry ; and secondly, owing to the stringent measures 

 taken by other countries, alarmed by reports of the prevalence of 

 the disease here, against the importation of British-grown potatoes. 

 According to the Report'' issued by the Intelligence Division of the Board 

 of Agriculture and Fisheries, 1911-1912, the actual loss occasioned to 

 the potato harvest here is very slight indeed, since the report states : 

 " There are probably scarcely five hundred acres in all England which 

 are under cultivation for potatoes as a field crop which are liable to 

 be affected while even in these the proportion of diseased tubers is 



' G. C. Cuiiiiiiigham in Plii/tup'ithDlogj/, ii (IDl'J). 



^ H. T. Giissow in i)apcr read before Assoc. Econ. Biol. Lundon. 'lOaster. HI 14.) 



' B. F. Lutman in Phi/lopdlhologi/, in (1913), p. 255. 



' A. S. Home in Jour, lioij. Hort. Hoc. xxxviit, p. 40. 



* Board of Agric. and Fisli. Annual Rcpt. Inldlitj. Dir., Pt. ii (!'.>i:}). p. 24. 



