526 



DISEASES OF CULTIVATED PLANTS 



only be infected during the seedling, or quite early period of 

 growth, hence, if seed-beds for the various kinds of cabbage 

 are properly limed, the plants will grow up free from disease. 







Vb 







Fig 157. Plasmodiophora brassicae. 1, young turnip 

 showing earl] itage of disease ; 2, cabbage showing clubb d 

 root; 3, two infected cells from root of cabbage, one con- 

 1. lining plasmodium, the other crowded with minute spores 



of th'' 1 1. 1 1 asite ; 4, three myxamoebae or motile bodies pro- 

 duced by the spores on germination. Figs. 3 and 4 highly 

 mag. 



It will be impossible to stamp out the disease unless proper 

 precautions are taken. In the case of cabbages grown in 



