1891.] PUBLIC DOCUMEXT — Xo. 33. 213 



TiiK Brown Rot of Stone Fruits. — Moiiil/a 

 fnictigcna Pers. 



The fact that great and sometimes ahnost total losses of 

 the crop occur among the stone fruits, the peach, plum 

 and cherrj', through the attack of this disease, has been for 

 some time recognized, more general!}', perhaps, in this 

 country than in Europe. Its effects have been described at 

 some length by some European writers on plant diseases, 

 while by others it is barely mentioned. So far as its 

 general characters and cause are concerned, it has been 

 pretty fully described by Peck,* Arthur, f Galloway^ and 

 Smith, § and a brief summary will suffice here. 



The disease is at first characterized by the browning of 

 the fruit, whose flesh then becomes shrunken and shrivelled 

 to a thin, tough pellicle over the stone, and remains in 

 this condition and resists decay for an indefinite period. 

 The term "mummied" aptly describes fruits which have 

 been thus affected. Soon after it first turns brown, there 

 may be seen thickly scattered over the surface of the fruit 

 the ashy spore tufts of the fungus which has been shown 

 to be the cause of the disease, and is known as Afoiiilia 

 fructigcna Pers. The vegetative threads of this fungus 

 ramify through the tissues of the fruit and break through 

 the surface, where they produce spores in chains at their 

 ends. When cultivated in the laborator}', these chains often 

 reach a ^^ry great length, and branch more freel}'" than is 

 the case out of doors (Figs. 17—19). It may be easily 

 observed on such specimens that the spores are formed by 

 a sort of budding, the terminal one being the newest ; and 

 that where branchinjj occurs it oriirinates in a terminal cell, 

 which assumes a somewhat triano-nlar form, and buds from 

 its two outer angles, as shown in Fig. 18. The spores, 

 when fully formed, fall from the chains, and are capable 

 of immediate germination. Under suitable conditions their 

 germ threads can penetrate the uninjured skin of fruits, or 



* Tliirty-fourth Report N. Y. State Museum, p. 35 (1881). 

 t Fourth Report N. Y. Aarric. Exp. St.ition, p. 254 (,l88oJ . 

 •% Report TT. S. Dep't. Agr., ISSS, p. 349. and Tlates V and VI. 

 ^ Jom-nal of Myfology. Vol. V, p. 123 (18S9). 



