1922.] Immunity Trials of Potatoes, 1921. 1149 



Purple Eye No. 5, Seedling 105), and these for the future will 

 be regarded as susceptible varieties. No wart disease occurred 

 on 41 kinds, but the Ministry was able to make a definite 

 declaration of immunity in the case of the following five 

 varieties only: — Dunvegan, Eanfurly Bed, The Celt, Barley 

 Bounty, and G.10. The first four are listed as Approved 

 Immune Varieties and G.10 can be listed when properly 

 named by the introducer. A number (21) of American varieties 

 of potatoes were included in these trials, and also in the trials 

 of the Scotch Board's Station. No disease was seen on any 

 of these varieties, but as the majority will probably not be in- 

 troduced to the British potato-growing industry, it is not pro- 

 posed unduly to lengthen the immune variety list by adding 

 all these names en bloc. Should, however, the sender wish to 

 introduce any of these varieties the [Ministry would be prepared 

 to list any distinct varieties that have successfully passed the 

 tests. It is interesting to note that varieties w T hich have proved 

 immune in America have also remained immune when tested in 

 this country, a fact which shows that the immunity of potatoes 

 from wart disease is not an unstable character. 



There were tested for the second time a number of varieties 

 whose immunity must still remain doubtful; of these Ben 

 Lomond and Ben Arthur are typical examples. 



Of the many (686) varieties included in the test for the first 

 time, a number (138) definitely contracted Wart Disease late in 

 the season. Many proved synonymous with existing varieties 

 and are referred to in the Report of the Synonym Committee of 

 the National Institute of Agricultural Botany for 1921, but the 

 following distinct varieties may now be definitely classed as 

 susceptible : — 



King Victor. Guardian. Farmer. 



Vitality. Jupiter. Rouge de Soissinaise. 



Improved Regent. Grigor's Seedling. Reed Major. 



Craigend Abundance. Esbie Selection. Cornicubia. 



Scarlet Marvel. Geante Bleue. 



Of the number that remained free from wart disease, a large 

 percentage were distinct and new to the Station. As previously 

 stated, the test last season was by no means severe, and it is 

 probable that a number in this grcup will prove susceptible 

 when the test is repeated under more normal conditions. 



A few of the stocks sent in were so mixed that it was 

 impossible to select the plants which represented the true 

 variety; the growth of other stocks, generally English and 



