1922.] Swedes Resistant to Finger-and-Toe. 3(>5 



d iets with a normal annual rainfall of HO in. recording 8.9 in. 

 in the month of July alone) the results were sufficiently promising 

 to make a second trial advisable. It is the object of this article 

 to discuss fully the results obtained in 1921. 



1921 Trials. — In order to keep these trials within reasonable 

 limits only four British varieties were tested, together with the 

 two Danish strains which had proved most resistant to clubroot 

 at Studsgaard and Herning in Denmark. 



The seed of the former varieties was obtained from seedsmen 

 in the ordinary way, whilst that of the Danish varieties was 

 obtained from the experimental station at Herning through the 

 courtesy of Mr. C. I. Christensen. 



The trials were carried out on three farms in Carnarvonshire, 

 viz. : — Dinas, Tregarth ; Dolgynfydd, Carnarvon; and Pennarth, 

 Clynnog. At each centre three series of plots were laid down, 

 and in addition, each series was divided to allow of comparison 

 of different treatments. 



In this way eighteen series of plots were kept under observa- 

 tion, and a thorough check upon the results was obtained. 



The swedes were sown on 13th May at Dinas, 80th May at 

 Dolgynfydd, and 2nd June at Pennarth. A good and uniform 

 plant was obtained at each centre, and considering the dry 

 season the progress of the crops, except so far as they were 

 affected by clubroot, was fairly good. The swedes were lifted 

 at all the centres at the end of November. 



Method of Examination and Stating Results. — The crop was 

 examined in the field immediately after lifting, and before the 

 roots were cleaned. Roots which showed no signs of disease, 

 and those so slightly attacked that the diseased part would be 

 removed in cleaning, were classed as sound. Roots so seriously 

 affected that no cleaning could remove the whole of the diseased 

 tissue, were classed as bad. The term destroyed was applied 

 only to such useless roots as appeared to be destroyed by clubroot. 

 The intensity of attack is shown in tables I and II by a figure 

 calculated from the proportions of roots of these three classes in 

 the crops. The figure "0" would signifv that the crop contained 

 none but sound roots, and is increased with the number of bad 

 and destroyed roots up to 20, which would indicate a totally 

 destroyed crop. This is a slight modification of the method used 

 by Christensen.* 



* Christensen, C. I., in Tidskrif t f or Plantcavl : vol. xxvi. pt, I 1!H7 (abstract 

 in Rcpt. of Int. Inst, of Agric. Rome, March 1918, p. 317). 



