1905.] A New Disease in Potatoes. 37 



comparison made in 1904 with one variety, viz., Charles Fidler, 

 in which case the crop from the third year's seed proved to be 

 under 7 tons, whereas new seed of the same variety yielded 13 \ 

 tons. 



A -suggestion is also made with regard to the improvement ot 

 existing varieties that have been in use for a number of years, 

 and which are still of excellent merit. Selection of the most 

 prolific plants is, it is pointed out, a branch of potato culture that 

 has received comparatively little attention from the ordinary 

 farmer, but this, carefully and systematically carried out with 

 deserving varieties, would doubtless mean to them a new lease 

 of life. In plant-breeding only the most productive plants are 

 kept, the unproductive being ruthlessly discarded, and thus it is 

 in great measure that new varieties are more prolific than older 

 ones. In view of these facts there need be little doubt that the 

 vigour of our older varieties may be increased, or at least main- 

 tained, by selection. 



Sphaerella tabtfica* a minute parasitic fungus, otherwise 

 known as Beetroot and Mangold Rot, has recently been found 



attacking - potatoes. This parasite has proved 

 A New Disease it .- . u «. *.u n 



in Potatoes ver ^ destructive to sugar beet on the Con- 

 tinent, and equally so to mangolds in this 

 country ; swede turnips have suffered to a less extent. It has 

 not previously been recorded as attacking potatoes. 



The disease first appears on the leaves in the case of beet and 

 turnips, and afterwards passes down to the root, and the same 

 course appears to have been followed with the potatoes ; as in 

 the tubers which were forwarded to the Royal Botanic Gardens* 

 Kew, for investigation, the earliest indication of disease was 

 observed in the vascular ring of the tuber, at the point where it 

 Joined the stem, down which it passed. Land that has pro- 

 duced a diseased crop should not be used for growing potatoes, 

 mangolds, or turnips for some years. 



See Journal, Vol. XL, Nov. 1904, p. 488. 



