This interesting disease was given attention in Europe about ten years ago. In certain foreign countries Phytophthora Rot seems to be quite common and destructive. It is said to occur in Switzerland during rainy seasons on apples and pears, rotting the fruit to a considerable extent. The disease also affects and brings about the death of apple "buds" in the Swiss nurseries. An outbreak is reported from Bohemia in 1910, and the trouble has at last been found in America. In 1915 it was discovered 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 Phytophtkora cactorum. Affected apples were first observed in July on those fruits nearest the ground. Earlier 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 resembles 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.
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 Bohmen. Zeitschr.
f. Pflanzenkr. 20: 257 - 261. 1910.
Fig. 40. - Phytophthora Rot of apple.