THE PLUMS OF NEW YORK. 127 



tacked, however, than any other group of plums, and the Insititias rank 

 next in immunity. No variety of the Domesticas has yet proved to be free 

 from the disease but strong claims are made that Middleburg and Palatine 

 are relatively free. 



Next in order of seriousness among the diseases which attack culti- 

 vated plums is the brown -rot ' (Sclerotinia fructigena (Persoon) Schroeter) 

 known also very commonly as the ripe-rot and sometimes as peach-blight. 

 The disease is most conspicuous on the ripe fruits of the various drupes 

 and is popularly supposed to be confined to the fruits alone. Such is not 

 the case, for it also attacks, and very vigorously oftentimes, the flowers and 

 shoots. The presence of the disease on the fruits is known by a dark 

 discoloration of the skin which is afterward partly or wholly covered by 

 pustule-like aggregations of grayish spores. The decayed fruits may fall 

 to the ground, or as is more usual in the case of plums, they hang to the 

 tree and as the juice evaporates become shriveled mummies, each mummy 

 being a storehouse of the fungus from which infection spreads the following 

 season. The twigs, flowers and leaves are known to be suffering from 

 inroads of the parasite when they are blackened as if nipped by frost. 

 In warm, damp weather the rot spreads with great rapidity and fruits touch- 

 ing in clusters or in boxes stored for shipping are well placed to spread 

 the epidemic. Destruction of the mummy -like fruits and all other sources 

 of infection, and spraying with bordeaux mixture are now practiced as 

 preventives, but so far as the crop is concerned with but indifferent success. 

 A better remedy than we now have is eagerly looked for by growers of 

 fruits. 



The hosts of this fungus show varying degrees of susceptibility to it, 

 the peach and the sweet cherries being more subject to it than plums. 

 Similarly, among plums some species and varieties are more susceptible 

 than others. Thus the Trifloras and Americanas, the latter especially 

 in the South, are injured more by the brown-rot than other species. The 

 idiosyncrasies of varieties in this regard are best shown in the discussions 

 of the individual sorts. 



Several interesting and sometimes destructive diseases of plums are 

 caused by various species of the fungal genus Exoascus. ' The most common 

 of these, and the most striking and destructive, is plum-pockets (Exoascus 



'Smith, E. F. Peach Rot and Peach Blight Journ. Myc. 5:123-134. 1889. Quaintance, A. 

 L. The Brown Rot, etc. Ga. Sta. Bui. 50:237-269, figs. 1-9. 1900. 



1 Atkinson, G. F. Leaf Curl and Plum Pockets Cornell Sta. Bui. 73:319-355, Pis. 1-20. 1894. 



