130 DISEASES OF CULTIVATED PLANTS 



withers and falls off. The injury is caused by a species of 

 Phytophthora, which, however, is not described. 



Two preventive methods are indicated, (i) To revert if 

 possible to the late harvested crop of former years. (2) 

 A more efficient method of prevention is the improvement 

 of the covers used for the bunches. The leaf covers used 

 are tied' over the bunches as soon as the rains begin. These 

 dry and crack in fine weather, and during long continued 

 rains rot and fall to pieces. The substitution of tin covers is 

 recommended. 



Butler, Agric. Journ. of India, i, p. 299 (1906). 



Lima bean mildew (Phytophthora phaseoli, Thaxter) is 

 the cause of serious injury to the Lima bean (Phaseolus 

 lunatus) in the United States. The pods more especially are 

 attacked, white felty patches of mould frequently cover the 

 entire surface. The young shoots are also swollen and 

 distorted. Less frequently it also develops on the leaves and 

 petioles. 



Conidiophores springing singly or in clusters through the 

 stomata, strongly swollen at the base, simple or sparingly 

 branched upwards, tapering, with scattered, swollen portions 

 above, corresponding to the origin of conidia, up to i mm. 

 high ; conidia lemon-shaped, with a prominent papilla, 

 hyaline, 25-30X15-20 /x, producing on germination 6-16 

 zoospores. 



Dilute Bordeaux mixture checks the spread of the 

 disease. 



Thaxter, Bot. Gazette, 14, p. 273 (1889). 



CYSTOPUS (LEV.) 



Sori or groups of conidiophores produced under the 

 epidermis of the host, bursting through when the conidia 

 are mature. Conidiophores in dense clusters, short, each 

 bearing a chain of superposed conidia. Conidia all alike, 

 colourless, and producing zoospores, or the terminal coni- 

 dium larger than the rest, and either sterile or producing a 

 germ-tube on germination. Oospores globose, coloured, 

 producing zoospores on germination. 



As both conidia and oospores produce zoospores on 



