1 1 1 . — Helminthosporiose 

 [Hehninthosporiiim Sacchari Butl. ii. sp.). 



A species of this well-known genus, many members of which 

 are parasitic on Gramifiece, is common on the leaves of sugarcane 

 at Pusa. The infected leaves first show small red spots, which 

 spread rapidly, chiefly in a longitudinal direction and, especially 

 towards the tip of the leaf, may run together to form long streaks. 

 The centre of the spot soon changes to a dirty straw colour, around 

 which the margin remains red for a time and then changes to dark 

 brown. The spots occur equally on the midrib, where they may 

 be confused with those caused by the leaf form of Colletotvichum 

 falcatum,^ and on the thinner part of the leaf When numerous, 

 they cause death of the leaf tissues beyond the limits of the spots; 

 the tip of the leaf often withers completely and there may be 

 long withered strips down the margins. 



The mycelium of the parasite is found in the leaf cells of the 

 spotted portion and also collects in small stromatic masses on the 

 surface of the spot. The hypha) are brown at the surface and in 

 the outer cell layers, but hyaline deeper in. They pass from cell 

 to cell through narrow cracks in the walls (PI. VI, Fig. 2), which 

 are especially noticeable in the thick-walled sclerenchyma which 

 overlies the bundles, but within the cells are swollen so as almost 

 to fill the cavity in the smaller cells. In the epidermis they fre- 

 quently form small stromatic masses. The cells appear to be 

 killed in advance of the growth of the fungus, as although the 

 hypha) are numerous in the dead cells, it is rare to find penetra- 

 tion of a still living cell. 



As soon as the centre of the spot begins to turn straw- 

 coloured, fructification occurs by the growth of sporophores from 



* Butler, E. .J. & A. Hafiz Khan. Red Rot of SugarcRne. Mem. Dcpt. of Apiic. in 

 India, Hot Sen, VI. No. 5, l!tl3. 



