THE POTATO DISEASE 65 



greatly improved the yield. Potatoes obtained from a 

 diseased crop should never be used as ' sets/ on account 

 of the probability, almost certainty, of the presence of 

 mycelium in the tubers. 



Diseased stems, leaves, and tubers should not be allowed 

 to lie and rot on the ground, neither should they be 

 thrown into the piggery nor on the manure-heap ; burning 

 is the most effectual method. The disease is most severe 

 where potatoes are grown in a low, damp district. 



Although all known varieties of potato are susceptible 

 to the disease, some are much more so than others, and 

 endeavours should be made to secure those varieties least 

 susceptible to the disease in a given district. 



De Ba.ry,fourn. Roy. Agric. Soc. Engl., vol. xii., 1876. 

 Jensen, Mem. Soc. Agric., vol. cxxxi., 1877. 

 Smith, Gard. Chron., July 1875. 

 Marshall Ward, Diseases of Plants, p. 59, figs. 

 Prillieux, Malad. des Plantes Agric., vol. i. p. 78, figs. 

 (1895). 



LIMA BEAN MILDEW 



(Phytophthora phaseoli, Thaxter.) 



A destructive disease has been described as attacking 

 Lima beans (Phaseolus lunatus) in the United States. The 

 pods are more especially attacked, less frequently the 

 leaves and petioles; it is not uncommon on the young 

 shoots. 



Diseased pods show white felty patches which sometimes 

 extend over the entire surface ; the young shoots are also 

 swollen and distorted. The disease spreads rapidly. 

 E 



