MARKET DISEASES OF APPLES, PEARS, QUIKCES 37 



into the stem (pi. 4, B). In apples the flesh surrounding the 

 bundles is slightly browned; in pears scarcely at all. In some va- 

 rieties of pears, notably Clairgeau, the flesh is in fact decolorized and 

 has a clear, water-soaked appearance very much like that of apple 

 flesh affected by water core. The flesh of both apples and pears 

 sometimes becomes slightly spongy but is usually as firm as sound, 

 healthy flesh; it rarely becomes soft and mushy, like that found in 

 decay produced by Rhizopus or blue mold. In cross section the area 

 affected by Phytophthora in both kinds of fruit has an indefinite 

 boundary so that it is impossible to make a clear separation of dis- 

 eased from healthy flesh, as can so easily be done in fruits attacked 

 by Rhizofus or blue mold. The affected flesh has no marked odor 

 or taste. 



In the orchard this rot occurs either on windfalls or on fruit hang- 

 ing low on the tree, hence it seems likely that the fungus Phytoph- 

 fhora causing it lives in the soil. Confirmation of this theory is 

 found in the fact that pears or apples laid on moist soil from or- 

 chards where the rot occurs and held at a temperature of 70° to 80° 

 F. will develop Phytophthora rot in 2 to 3 weeks. The fungus is 

 apparently able to penetrate the uninjured skin of the fruit, since 

 on many of the infected specimens observed it was impossible to 

 discover skin breaks of any sort. On the market Phytophthora rot 

 has been found in boxed apples and in basket shipments of low-grade 

 pears. 



To prevent the appearance of Phytophthora rot in marketed fruit 

 it is apparently only necessary to avoid putting windfalls into the 

 pack. {4.2, 75, 11 4, 196, 235.) 



PINK-MOLD ROT 



(Cephalotliecidini roseum (Fr.) Cda.) 



Pink-mold rot is chiefly an apple disease, though it is sometimes 

 found on summer or fall varieties of pears. It was formerly more 

 prevalent and destructive than at present, because of the custom, 

 now virtually discontinued, of piling apples and allowing them to 

 " sweat " before packing. It is usually found following scab and 

 is still rather common in storage and transit on Baldwin, Rhode 

 Island Greening, and other varieties susceptible to scab. It may 

 also occur on apples while they are still on the tree. On certain 

 russet varieties the rot sometimes follows an injury resembling 

 Jonathan spot, and it may occur independent of scab or any other 

 injury. In the latter case the fungus apparently enters at the 

 lenticels. The disease is more common in New York, Ohio, Mary- 

 land, Virginia, and West Virginia than in any other parts of the 

 country. It has also been reported from Nebraska. 



In its most common form, that is, following scab, the disease is 

 found in two rather well-marked stages, with various transition 

 stages between them. In the. first of these the rot appears as defi- 

 nitely sunken brown bands about an eighth of an inch wide encirc- 

 ling scab spots. At such places there is sometimes a growth of white 

 fungus threads, or under warm moist conditions a pink mass made 

 up of these threads and the pink spores they produce. If condi- 

 tions are favorable, the second or final stage of the rot soon follows. 



