MARKET DISEASES OF FRUITS AND VEGETABLES 19 



Brown core is considered to be associated with low-temperature 

 storage (30° to 32° F.). However, the tendency for the disease 

 to develop appears to be inherent in the fruit when it is harvested. 

 This disease usually does not develop in stored apples until 

 January and becomes most serious in apples stored for long 

 periods at 30° to 32°. It increases in severity after apples are 

 removed from cold storage. 



Perhaps the most important factor predisposing apples to 

 brown core in the orchard is an extended period of cloudy, rainy 

 weather when the apples are coming into maturity. It has been 

 shown that the shading of limbs with cheesecloth increases brown 

 core, whereas the shading of individual fruits and defoliation 

 had no effect. Certain orchard practices such as picking at the 

 proper stage of maturity and reduction of nitrogen fertilizer have 

 been found to decrease susceptibility to brown core in certain 

 seasons. However, when conditions favored a serious development 

 of brown core such measures were ineffective. Smock (125) con- 

 sidered controlled-atmosphere storage at 40° F. to be the most 

 practical means of preventing brown core. 



(See 71, 97, 123, 125.) 



INTERNAL BROWNING 



Internal browning is decidedly regional in its occurrence. It is 

 particularly serious in Yellow Newtown apples grown in the 

 Pajaro Valley in California, and it occurs also in Yellow Bell- 

 flower and other varieties grown in that section, where the 

 weather is cool and cloudy or foggy through the growing season. 

 It is occasionally found in Yellow Newtown grown in other States, 

 notably Washington, Oregon, and New York, and in Rhode Island 

 Greening grown in New York. Traces of the disease have been 

 found in Virginia-grown Yellow Newtown, but ordinarily condi- 

 tions there do not favor development of the disorder. 



Internal browning does not manifest itself by any abnormal 

 appearance of the skin of the apple and can be detected only by 

 cutting into the fruit. Rather frequently it appears only around 

 the core, the outer fleshy portion of the apple remaining normal 

 in appearance. Occasionally only the outer flesh is involved; 

 usually, however, when internal browning develops in the outer 

 fleshy portion it is accompanied by browning around the core. 

 The general tendency of the disease is to develop uniformly 

 throughout the tissue (pi. 9, C, D). Internal browning occurs in 

 firm, sound-appearing apples; this fact, together with the char- 

 acteristics just given, separates it readily from internal break- 

 down. The latter develops in overripe apples, usually appearing 

 on the skin and progressing in localized areas into the flesh. 



The tendency to develop internal browning in storage is in- 

 herent in the fruit when it is harvested. In addition to low tem- 

 perature and lack of sunlight, certain other factors have been 

 found to increase susceptibility. The Yellow Newtown has been 

 found to be more subject to internal browning when the fruits 

 are large, especially from trees bearing a light crop, when they 

 are harvested late, and when they are delayed in reaching storage. 

 The usual cold-storage temperatures (30° to 32° F.) are particu- 

 larly favorable to development of internal browning. The brown- 



