FUNGOID DISEASES OF POTATOES 87 



propagating the disease. Under favourable con- 

 ditions of growth the resting stage (sporangium, 

 Fig. 24, B) of the fungus is produced, whereby the 

 winter is brooded over, for apparently there is no 

 growth in the tuber after lifting. 

 Preventive Meastires. — 



1. Dust the "seed" potatoes with (lowers of 

 sulphur before planting. 



2. Plant sets free from the disease. 



3. Grow disease-resistant varieties, e.g. Lang- 

 worthy. 



4. Avoid planting on land where the disease has 

 occurred. 



(See " Highland and Agr. Soc. Journal," 1903, 



P- 312.) 



Wart Disease is scheduled as a notifiable disease 

 and must be reported at once to the Secretary, 

 Board of Agriculture and Fisheries, Whitehall 

 Place, London, S.W. 



VII. Corky Scab or Powdery SQKV>(Spongospoya 

 subterranea) occurs in the form of powdery ir- 

 regular patches on the surface of potatoes. It 

 may be of a serious nature where potatoes are 

 grown frequently on the same land ; especially 

 during a wet season. The disease is spread by 

 planting affected tubers. It has been declared a 

 notifiable disease, and cases must be reported 

 without delay to the Secretary, Board of Agricul- 

 ture and Fisheries, Whitehall Place, London, S.W. 



