This disease probably does not occur in America, but is discussed in order that a comparison of Brown Rot of pome - fruits in Europe and America may be made.

European Brown Rot of apple affects the fruits in a manner similar to the American Brown Rot (see Fig. 37). But European Brown Rot also affects the flowers, shoots and foliage. Diseased flowers are blighted. The woody parts, twigs and limbs, are cankered (Fig. 38). The formation of a European Brown Rot canker on apple ordinarily proceeds as follows: a hanging mummy presses against a fruit-spur and the two adhere firmly; the pathogene, Sclerotinia fructigena, then grows from the apple-mummy to the branch. An affected branch may be girdled and under conditions of high relative humidity grayish tufts - conidial structures of the pathogene - develop on the surface of the canker. Another method by which the canker may originate is by the passage of the pathogene from an affected blossom through the fruit - spur into the twig.

Fig. 38.   Brown Rot canker of apple, caused by Sclerotinia fructigena (specimen from England).

Fig. 38. - Brown Rot canker of apple, caused by Sclerotinia fructigena (specimen from England).

References

Salmon, E. S. A canker of apple trees caused by the brown rot fungus. Gard. Chron.

3: 47: 327. 1910. Molz, E. Ueber die Bedingungen der Entstehung der durch Sclerotinia erzeugten Schwarzfaule der Apfel. Centralbl. f. Bakt. 2:17: 175188. 1906. Salmon, E. S. A canker of apple trees caused by the brown rot fungus. Southeastern Agr.

Col. (Wye) Rept. on Econ. Myc. 1909 - 1910:

33 - 35. 1910. Aderhold, Rud. Uber eine vermuthliche zu MoniHa fructigena Pers. gehorige Sclerotinia.

Deut. Bot. Ges. Ber. 22: 262 - 266. 1904.