BUTLER AND HAPIZ. 167 



fungi which depend on the wind for their dissemination and the chan- 

 ces of the individual spore alighting on a susceptible part of the cane 

 stem, this point becomes of significance. But, as was pointed out in 

 1906, there is another part of the cane on which a fungus agreeing 

 in morphological characters with Colletotrichum falcatum is frequently- 

 found and produces spores in greater quantity and more exposed 

 to the wind than the stem form. This is the midrib of the leaf. 

 Earlier writers have reported the occurrence of the fungus as a 

 saprophyte on old, withered leaves of sugarcane.' That it also 

 occurs not uncommonly as a leaf parasite seems to have escaped 

 the notice of most observers, though Edgerton^ refers to it. Ex- 

 periments were carried out at Pusa to determine if the leaf form 

 could infect the stem and conversely. 



Three of these experiments have been described above (page 158) 

 where it was shown, firstly, that wound inoculation with a pure 

 culture of the midrib form caused visible infection of from one to 

 three internodes after three months and, when the inoculated canes 

 were planted, red rot developed in them with severity, and, secondly, 

 that inoculation of the setts, immediately before planting, causes 

 just as severe disease as when the stem form of the fungus is used. 

 In another case a pure culture of the leaf fungus was used to in- 

 oculate Striped Mauritius cane, 11 inoculations being made to- 

 wards the base and ten towards the apex of the stem. In a little 

 over two months, 7 of the former were examined and showed 

 1 + 3 + 2 + 1+0 + 4^ + 4: internodes affected. In 6 of the canes 

 inoculated towards the apex, 34-l+0-t-l-l-l-f-2 internodes were 

 found diseased after the same period. These experiments show 

 that the leaf fungus can attack the stem and the cut setts, the 

 symptoms produced being those of typical red rot. 



The parasitism of the midrib form was next tested on leaves. 

 In the first experiment spores from a pure culture were sown in 

 drops of water on the upper surface of the uninjured midrib of 

 growing canes. Out of 6 inoculations, none succeeded. The ex- 



' Went, F. A. F. C. Notes on Sugarcane Diseases. Ann. of Bot, X, 1896, p. 588. 

 2 Edgerton, loc. cit., p. 4. 



