320 DISEASES OF CROP-PLANTS 



sometimes a faint yellowish outer margin. The spots are 

 irregular in shape, somewhat elongated in the direction of the 

 length of the leaf, usually less than half an inch in length, but 

 often confluent. When they are abundant they are apt to 

 cause premature death of the whole leaf. 



Marked local epidemics sometimes occur in moist weather. 

 When the infestation occurs on mature canes, as it often does, 

 no considerable harm can result, but earlier outbreaks when 

 at all severe must administer a somewhat severe check to growth. 

 Their occurrence is usually so erratic that they cannot be anti- 

 cipated by any preventive measure. 



Eye-Spot. 

 The eye-spot disease of the leaves was originally reported 



Fig. 133 Helminthosporium Sacchari 

 From Memoirs, Dept. Agri., India 



from Java, the fungus being named Cercospora Sacchari Br. d. H. 

 It is now usually admitted to be a Helminthosporium and is 

 probably identical with H. Sacchari Butl. found in India. The 

 affection is known to occur in Cuba, Jamaica, Porto Rico, 

 Barbados and Trinidad. In the last-mentioned island C. B. 

 Williams reports that during the last few years it has been 

 found only on D 109 in certain small areas, and only exception- 

 ally appears before the month of December. In 19 19 a severe 

 local epidemic two or three months earlier than this soon passed 

 off. The affection takes the form of elongated spots and streaks, 

 red to dark brown in colour and developing a straw-coloured 

 centre. In severe infestations they are crowded together and 

 the leaves are so generally discoloured that the stools have a 

 blighted appearance. In such cases the spots may be found 

 even on leaves just unfolded, and a distinct check to growth can 

 be detected. 



The conidiophores are stout, erect, rather rigid hyphae. 



