1920.] 



The Ormskirk Potato Trials : Report. 



699 



The badly mixed stock of Great Scot, for instance, could have 

 been purified on the trial grounds, as it was evident at planting 

 time that tubers with deep purple sprouts were Arran Chief, 

 but they were deliberately planted as sent. Growers should 

 refer to the descriptive list of the immune varieties for the 

 colour of the sprouts. Although the degree of purity in the 

 immune stocks was high, it was surprising to find that many 

 of the new varieties sent for the first time consisted of very 

 mixed stocks. The greatest care is necessary to prevent new 

 varieties from becoming contaminated with others already in 

 cultivation. 



A notable point in the Report is the fact that during 1919, 

 for the first time since the trials had been carried out at 

 Ormskirk, it w^as observed that the climatic conditions of the 

 season had a marked effect on the intensity of the disease. In 

 previous years many of the more highly susceptible varieties 

 have produced warted tubers in excess of clean tubers. During 

 the season under review, in practically every case, the propor- 

 tion of visibly clean tubers was far in excess of the warted 

 specimens. In those varieties where the proportion of clean 

 tubers has been, as a rule, greater than that of warted 

 specimens, a crop of the latter was relatively much less than in 

 previous years. The Epicure variety, for instance, of which 

 the warted tubers gave in 1918 1 ton 12 cwt., yielded in 1919 

 only 3 cwt., and in another case 1 cw^t. The yield of President 

 for w^arted tubers fell from 3 tons 6 cwt. to 15 cwt. 



During the year the Ormskirk experiments in steam sterilisa- 

 tion of infected soil w^ere continued, but results w^ere indefinite. 

 It should be noted, however, that Professor Barker has obtained 

 a clean crop in soil sterilised at lOO^C. for IJ hours. 



The Report contains a large body of valuable infor- 

 mation which should be of great assistance to potato 

 growers. Among the principal features are notes on immune 

 varieties previously tested and comparative tables showing the 

 difference between the yield of immune and susceptible 

 varieties, as well as an illuminating paragraph on types and 

 synonyms. A subsidiary, but not less valuable, report is that 

 on the cooking qualities of nine well-known varieties, but in 

 this connection it is to be noted that the quality of a potato is 

 largely dependent on soil. The flavour of the varieties 

 mentioned would in all probability be different if the tubers 

 were grown on other soils. 



