Fig. 47. Powdery scab showing apparent decay following a severe 

 attack. The pustules are still in their original condition and in no way 

 resemble scab spots. 



,M' 



4ii '^>' 





Fig. 48. A badly withered tuber — -a common occurrence with tubers 

 affected by powdery scab, after remaining some time in storage. The 

 tops of nearly all of the pustules have disappeared, leaving scab-like spots- 



