Sept 15, 1925 
Cladosporium Leaf Mold of Tomato 
523 
Seeds in the affected region were dark brown in color. In both 
pericarp and placentae there was, in certain of the green fruits, some 
advance invasion of the blackening visible along the vascular bundles 
beyond the generally discolored region. 
Dissection of the less blackened fruits, such as those showing a 
collar of black areas (pi. 1, D), disclosed the fact that the vascular 
bundles in the pericarp connecting these surface lesions with the 
torus were darkened. Upon removal of the torus it was found that 
usually there was a distinct darkening of the bundles in the scar, 
often more pronounced on the side showing the more extensive dis¬ 
coloration below. 
There were other symptoms rather frequently associated with the 
disease in which the normal form of the fruit was considerably altered. 
One type of infection was represented by blackened furrows radiating 
from the stem end, in which the discoloration of the pericarp was 
rather deep seated (pi. 2, E). Short transverse cracks in these fur¬ 
rows were common, and it seemed evident that both the cracks and 
the furrows were attributable to a localized retardation of the growth 
of the fruit tissues. Dissection of such fruits showed that the dark 
color of the furrow was due to blackened tissue surrounding an under¬ 
lying vascular bundle. 
The affected fruits generally were somewhat asymmetrical or 
one-sided, the retarded side showing- the most discoloration. This 
lopsidedness sometimes was very extreme, in which case the atrophied 
side was usually traversed by a few folds or furrows radiating from 
the torus toward the stylar scar (pi. 2, A, B). Upon cutting certain 
of these fruits which showed rather slight external blackening, the 
startling discovery was made that the stem end of the placentae in 
some of the locules was brown and atrophied, and bore small dark 
bodies which were found to be stunted, infected ovules (pi. 2, F). 
Once the significance of this lopsided condition of the fruits was 
appreciated, it was noted that many fruits of this character showed 
little or no discoloration, other than a tendency for the atrophied 
side to be yellowish rather than green or red. Many of such fruits 
developed the black color upon incubation, always more pronounced 
on the atrophied side, and other evidence was obtained (to be pre¬ 
sented later) -which indicated that this lopsided condition might be 
due to the retardation of growth on one side by this fungus under 
consideration. 
It must be admitted, however, that this lopsidedness is not unlike 
that illustrated by Munson (9, p. 49) and attributed by him to 
incomplete pollination, an explanation which has been corroborated 
by Fink (.2) and by later workers. It would seem, therefore, that 
the lopsidedness of tomatoes in the greenhouse may be due to more 
than one cause; in fact, mosaic necrosis and atrophy of a locule may 
also cause this condition. 
Another striking symptom was the tenacity of the diseased fruits on 
the pedicels. Generally, the affected fruits were harder to remove 
from the plant than the normal fruits, and they did not fall off. 
THE CAUSAL FUNGUS 
An examination of unstained, free-hand sections of the darkened 
tissues revealed the presence of dense aggregates of coarse brown 
mycelium in the intercellular spaces (pi. 3, A, B, C; pi. 4). From the 
