34 MISC. PUBLICATION 168, U. S. DEPT. OF AGRICULTURE 



no evidence of freezing in transit. Internal break-down may be 

 followed by browning, but this color change, unlike that which 

 often follows freezing injury, does not begin in the main fibro- 

 vascular bundles (in cross section, the 10 dots that surround the 

 core). Instead, it may begin at any place in the flesh and usually 

 does begin at many places. (For further description of internal 

 break-down, see page 37.) 



Internal break-down is usually worse in large apples and more 

 marked at the calyx end than at the stem end. Freezing injury 

 may affect apples of any size and is not necessarily or uniformly 

 worse at one end of an apple than at the other. When one side of 

 an apple or even the whole apple shows in cross section a uniform 

 brown color, it is hard to determine whether the condition is 

 freezing injury or internal break-down. Reliance should then be 

 placed not on any one symptom or the examination of one apple 

 but on all the symptoms that can be found in as many apples as 

 can conveniently be examined. 



Water-soaked bruises are not a sure sign of freezing injury, 

 as will be seen by reference to Bruises, page 21. 



(See 23, 35, 77, 116, 118, Ul.) 



FREEZING INJURY WHEN APPLES AND PEARS ARE YOUNG 



When freezing temperatures occur at blossoming time or soon 

 afterward, the fruits that remain on the trees may nevertheless 

 have suffered sufficient injury so that as they come to maturity 

 they show various abnormal conditions. One of these conditions 

 is the familiar frost russet. Perhaps the most common form of 

 mild frost injury is a russeted ring lining the calyx cavity and 

 occasionally extending outward from the cavity for \/% inch or 

 more. On apples and pears frost injury frequently takes the form 

 of bands encircling the fruit about halfway between the two ends 

 (pi. 3, C). In addition, frost russet on both apples and pears 

 sometimes has the diffuse irregular form characteristic of spray 

 injury and rain russet. 



A second condition, seen less frequently and only on apples, is 

 persistence of the green color at the calyx end on mature fruits 

 which over the rest of their surface have the color normal for the 

 variety. The persisting greening varies greatly in intensity and 

 in the amount of surface covered. It may or may not be accom- 

 panied by russeting. Affected areas are occasionally so flattened 

 and so dark green that they look like apple-cedar rust spots, but 

 they do not, of course, show the pustules characteristic of rust. 

 Badly damaged specimens are nearly always distorted at the 

 blossom end, may have only a few poorly developed seeds or none 

 at all, and usually show in cross or longitudinal section a blotchy 

 or streaked browning in the flesh underlying the green areas. 



Fruit Spot 



(Mycosphaerella pomi (Pass.) Lindau) 

 OCCURRENCE and symptoms 



In the United States fruit spot (Brooks' spot) is most common 

 east of Michigan and north of North Carolina and Tennessee. 

 It is occasionally serious in southwestern Missouri and north- 

 western Arkansas. It causes the greatest losses in New England, 



