Disease of Rubber caused by Ustulina Ronata. i6t 
Inoculation Experiments. 
After pure cultures of the fungus had been obtained, inoculation 
experiments were carried out upon seedling rubber plants growing 
in 'pots and upon trees about four years of age, situated on the 
slope of a hill. Blocks of wood on which the fungus was growing 
in pure culture were tied or placed against the main root of the 
seedling a little below the level of the soil. With the four-year-old 
trees either the main root or one of the larger laterals was inocu¬ 
lated in the same way. In three of the seedling plants thus inocu¬ 
lated the wood block bearing the fungus was placed against a wound 
made in the root with a scalpel; in three others the fungus was 
tied against the uninjured surface. A month later the leaves of one 
of the inoculated and unwounded plants began to droop, and, shortly 
after, investigation shewed that the plant was diseased at the collar, 
and there was clear indication that the fungus had spread from the 
wood block into the plant. Sections shewed a brown discolouration 
of the wood and bark of the root and collar above the place against 
which the wood block had been tied, but no black lines were present 
in the tissues. The pith was rotten for two inches upwards from 
the region of inoculation, and a hyaline mycelium was densely 
aggregated along the line of the cambium, where it formed a kind 
of pseudoparenchyma. 
A week later, i.e., five weeks after inoculation, two other seedling 
plants, both of which had been wounded, began to droop, and 
examination shewed that they were affected in the same way as the 
seedling described above. The three other plants remained healthy. 
The third wounded plant, which did not become affected, shewed 
only a slight discolouration around the wound which was already 
partly healed over. Thus in this series of experiments, the fungus 
entered and successfully infected one unwounded plant and two 
wounded ones. 
Of the fourteen four-year-old trees which were inoculated, 
eight were wounded before inoculation and six were not injured. 
The wounds made in these trees reached as far as the wood. Six 
weeks after inoculation the trees were examined, when it was found 
that the fungus had made considerable progress in each one of the 
wounded roots that had been inoculated, but, with one doubtful 
exception, had not penetrated the roots which had not been injured. 
The wood around the wounds through which the fungus had 
entered was markedly discoloured. Control wounds against which 
the fungus was not placed shewed much less discolouration in the 
