1922.] Swedes Resistant to Finci: u-and-Toe. 



'MY.', 



have succeeded in stamping out clubroot, but in general the 

 position in the country with regard to this disease has not 

 changed very appreciably during the last twenty years. 



Whilst it is true that liming is not usually resorted to on the 

 scale which is found necessary to check clubroot, this is not alto- 

 gether to be attributed to slackness or lack of knowledge on the 

 part of farmers, but in many cases to the real difficulties experi- 

 enced in carrying out remedial measures. 



It is perhaps significant that clubroot is serious in stock- 

 raising districts in the North of England, and in North Wales — 

 essentially pastoral areas. These districts have, generally 

 speaking, a soil rich in humus and a relatively high rainfall — 

 factors which will tend to reduce soil aeration and presumably to 

 increase soil acidity. Moreover, under these conditions lime avill 

 often be applied to grass in preference to arable land. Inciden- 

 tally it may be observed that liming is a costly and laborious 

 operation. The cost of applying two tons of lime at present 

 prices will be at least £5 per acre, and in some cases — as in 

 North Wales — where a farm may be as much as ten miles from 

 a railway, the cost and labour involved become prohibitive. 



These facts, taken in conjunction with the opportunities which 

 occur for infecting land through farmyard manure and the com- 

 mon farm practice of feeding off roots to sheep on grass which 

 will eventually be broken up, often result in the soil being kept 

 permanently contaminated with clubroot spores. 



So long as these conditions exist it is not reasonable to expect 

 any radical change in the extent to which lime is employed and 

 the uses to which it is put. It becomes necessary therefore, to 

 determine whether any other method of controlling the disease 

 is available. 



The most obvious alternative is the production of resistant 

 strains of swedes which can be relied upon to give a good crop 

 even on land badly contaminated with clubroot. This possibility 

 has received the attention of some seedsmen in this country, 

 and in Denmark several highly resistant kinds of swedes have 

 been produced by selection from two old Danish varieties, 

 Klank and Bangholm Pajberg. 



Preliminary Trials in 1920. — With a view to testing the resist- 

 ance of varieties of swedes to clubroot under the conditions 

 usually prevalent in North Wales, preliminary trials were laid 

 down on three farms in 1920. In these trials eleven British 

 varieties were tested alongside two Swedish and two Danish 

 kinds. Although the season was an abnormally wet one (dis- 



