44 DIPLODIA CORCHORI SYD. 
uninjured cuticle and whether, if so, they do so by virtue of a special cutin- 
dissolving enzyme! or merely by mechanical pressure, as stated by recent in- 
vestigators* in the case of other parasites, remains to be settled. It cannot be 
overlooked, however, that in the field the disease could spread rapidly even 
supposing that the epidermis of the host was impervious to the fungus. An easy 
point of entry is afforded by the numerous lateral branches which exist as small dry 
twigs, and it has already been mentioned that, in the field, a number of infections 
appear to originate in this way. 
Inoculations. 
Inoculations with pure cultures of Diplodia Corchori were first carried out 
during September, 1917. The plants used for the experiments were healthy jute 
stems, of the variety “ kakya bombai,”’ standing 7-10 feet high, along the eastern 
edge of the Pusa crop. 
Experiment I. Three plants each received asmall tangential cut on the stem 
surface, and the wound was infected with a small piece of agar culture of D. Corchori ; 
two of the plants had the wound infections bound up with oiled paper. In each 
case a brown stain appeared at the seat of infection and spread up and down the 
stem ; pycnidia and spores rapidly developed on the diseased tissues and when 
the discoloration had completely ringed the stem, the plant withered and lost its 
leaves. All the plants were dead in from 10 to 14 days after infection, the fungus 
spreading up and down the stems, which were left standing as blackened sticks. 
Experiment II, Three plants were infected with pure cultures of D. Corchori, 
small portions of agar cultures being placed at the base of lateral shoots. These 
lateral shoots are quite small, about 1-3 inches long, and as a rule do not develop 
further, but are left on the mature plant as short dead twigs. In one of the plants 
the point of mfection was loosely bound up with oiled paper. Four days after 
infection the lateral shoots were dead and black and a small brown stain was 
spreading in the axils of these shoots on each stem. In the case of the infection 
which had been bound up, the disease spread rapidly up and down and round the 
stem, as in Experiment 1, and death took place about 14 days after infection. 
Pyenidia and spores of Diplodia were abundantly developed and the fungus was 
re-isolated in culture from these spores. Near the seat of infection, where the 
fungus was most strongly developed, the bark became cracked and the brown 
? Wiltshire, S, P. Infection and Immunity Studies on the Apple and Pear Scab Fungi 
(Venturia inaequalis & V pirina).” Annals uf Applied Biology, Vol. 1, January, 1915 
* Blackman, V. H. & Welsford, E. J. “Studies in the Physiology of Parasitism.” 
Annals of Botany, XXX, July, 1916. 
* Brown, W. “ Studies in the Physiology of Parasitism.’’ Annals of botany, XXX, 1916. 
* Dey, P. K. “Studies in the Physiology of Parasitism.” Annals of Botany, XX} III, 
July, 1919. 
