CLADOSPORIUM LEAF MOLD OF TOMATO: FRUIT 
INVASION AND SEED TRANSMISSION 1 
By Max W. Gardner 2 
Associate in Botany , Purdue University Agricultural Experiment Station 
INTRODUCTION 
In a fall crop of Bonny Best greenhouse tomatoes at La Fayette, 
Ind., leaf mold caused by Cladosporium fulvum Cke. occurred in 
epiphytotic form in 1923 and produced a very prevalent and destruc¬ 
tive, blackened, stem-end infection of the fruits of all ages. Oppor¬ 
tunity was afforded to make a study of a large number of these 
infected fruits showing a wide range of symptoms. 
The leaf-mold fungus has not been generally supposed to invade 
the fruit, although Plowright (11)* in 1887 described and illustrated 
a fruit lot. attributed to this fungus; Halsted (4) reported a rot 
resulting from inoculations with this fungus; and, according to 
Makemson (8, p . 317), Ferraris reported that it caused a scab disease 
of the young fruits. The symptoms observed in this outbreak at 
the Indiana station did not in any way resemble the scattered lesions 
described by Plowright or the scab type of lesion. In fact Plow- 
right’s description of stem stripes and his picture of the fruit lesions 
would indicate that the mosaic disease was present in the greenhouse 
from which he received the specimens. Nor is there any likelihood 
that this rot is related to that attributed by Plowright (10) and 
Smith (15) to Cladosporium lycopersici, inasmuch as that was a 
blossom-end-rot infection. 
Makemson (8, p. 317), who made a study of this disease in Michigan 
greenhouses, found that all parts of the blossom, including the ovaries 
and young fruits up to the size of a pea, were infected. He reported 
blasting of the flowers by this fungus, and one case of a fruit oUe- 
fourth grown which bore conidiophores and spores. However he 
was unable to infect fruits by wound inoculation. 
Other stem-end rots of tomato have been described. The stem- 
end rot reported by Dickson (1) does not resemble the Cladosporium 
rot in color and was caused by a Botrytis species. A dry, black, 
stem-end rot of green field-grown tomatoes in Virginia, resembling 
the one under consideration, but caused by PliytovMhora infestans, 
was described and illustrated by Reed (12, p. 8) and by Fromme and 
Thomas (3, p. 8). 
SYMPTOMS OF FRUIT INFECTION 
The symptom which first attracted attention to this infection at 
the Indiana station was a sharply delimited jet black circular 
discoloration on the stem end of the young green fruits (pi. 1, A). 
1 Received for publication Sept. 9, 1924; issued October, 1925. Contribution from the Department of 
Botany. Purdue University Agricultural Experiment Station, La Fayette, Ind. 
2 The writer wishes to acknowledge his indebtedness to Prof. H. S. Jackson for helpful suggestions. 
* Reference is made by number (italic'* to “Literature cited,” p. 539. 
Journal of Agricultural Research, 
Washington, D. C. 
( 519 ) 
Vol. XXXI, No. 6 
Sept. 15, 1925. 
Key No. Ind.-14 
