152 MANUAL OF FRUIT DISEASES 
on Oldenburg apples while still hanging on the tree at Ithaca, 
New York, by the junior author. Later it was found in market 
fruit. So far, it has done no great damage in the United States, 
partly due, no doubt, to its very limited range. Up to date it 
has not been reported outside of New York State, although it 
doubtless occurs, to some extent 
at least, in several of the apple 
regions of North America. 
The disease is induced by the 
fungus Phytophthora cactorum. 
Affected apples were first ob- 
served in July on those fruits 
nearest the ground.  Larlier 
infections were not seen. These 
facts indicate strongly that the 
source of the inoculum is the 
soil. Infections occur up to the 
time of the ripening of the fruit. 
A brown-rot is produced which in many respects closely re- 
sembles fire-blight lesions on apple fruits (Fig. 40). The 
affected portion appears water-soaked at first, the margin is not 
definite, and there are no external evidences of fungus fruiting 
bodies. 
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Fig. 40. — Phytophthora-rot of apple. 
REFERENCES 
Whetzel, H. H., and Rosenbaum, J. The Phytophthora rot of apples. 
Phytopath. 6: 89-90. 1916. 
Osterwalder, A. Die Phytophthorafaule beim Kernobst. Centralbl. 
f. Bakt. 2: 15: 435-440. 1905. 
Bubak, Fr. Die Phytophthorafaule der Birnen in Béhmen. Zeitschr. 
f. Pflanzenkr. 20: 257-261. 1910. 
